The Wealden (non-marine Lower Cretaceous) of the Wessex Sub-basin, southern England

Proceedings of the Geologists’ Association 123 (2012) 319–373

The Wealden (non-marine Lower Cretaceous) of the Wessex Sub-basin,southern England

Jonathan D. Radley a,*, Percival Allen b,1

a School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UKb Postgraduate Research Institute for Sedimentology, The University of Reading, PO Box 227, Whiteknights, Reading RG6 6AB, UK

A R T I C L E I N F O

Article history:

Received 16 November 2011

Received in revised form 6 January 2012

Accepted 6 January 2012

Available online 8 March 2012

Keywords:

Geological Conservation Review

Wessex Formation

Vectis Formation

Wealden

Lower Cretaceous

Wessex Sub-basin

Southern England

A B S T R A C T

The Wealden Beds (non-marine Lower Cretaceous) of the Wessex Sub-basin, southern England, are

exposed principally in coastal sections on the Isle of Wight and in Dorset. Geological Conservation

Review sites within these strata have been extensively documented since the earliest days of geological

enquiry in Great Britain. The succession is dominated by the alluvial Wessex Formation which

demonstrates a broad east–west transition from meanderplain lithofacies to coarser-grained alluvial

sediments, in relative proximity to the Cornubian source massif. The meanderplain sediments on the Isle

of Wight are of international importance for their plant and animal fossils, the latter including many

dinosaurs and their trackways. Upper Barremian transgression resulted in the spread of muddy lakes and

coastal lagoons from the Weald Sub-basin into the eastern part of the Wessex Sub-basin, around or

through the Purbeck–Isle of Wight structure. The resulting richly fossiliferous mudrock-dominated

strata are now represented by the Vectis Formation on the Isle of Wight and in Swanage Bay, Dorset. The

Geological Conservation Review sites in the Wessex Sub-basin are documented and interpreted, with

particular reference to research history, chronostratigraphy, structural context, palaeoenvironments,

palaeobiology and palaeoclimatology. New directions for research are proposed, as applicable.

� 2012 The Geologists’ Association. Published by Elsevier Ltd. All rights reserved.

Contents lists available at SciVerse ScienceDirect

Proceedings of the Geologists’ Association

jo ur n al ho m ep ag e: www .e ls evier . c om / lo cat e/p g eo la

1. Introduction

This chapter describes Geological Conservation Review sitesalong the south-east and south-west coasts of the Isle of Wight(Fig. 1) and along the southern Dorset coast (Isle of Purbeck andWeymouth areas; Fig. 2). These areas constitute the northern partof the mainly offshore Wessex Sub-basin (Figs. 3 and 4). The coastalexposures of Wealden strata have attracted considerable attentionsince the earliest days of geological enquiry (e.g. Webster, 1816;Conybeare and Phillips, 1822; Fitton, 1824, 1836). Petrographic,geochemical and palaeontological studies of the predominantlyalluvial Wealden succession (Figs. 5 and 6) have similarly supplieda wealth of palaeoenvironmental, climatic and palaeobiologicaldata, and have an important bearing on the tectonic developmentof southern England during the Early Cretaceous.

2. Research history

Fitton (1836) provided the first key stratigraphic account of theWealden of the Isle of Wight and Dorset. Further details and

* Corresponding author.

E-mail address: [email protected] (J.D. Radley).1 Deceased.

0016-7878/$ – see front matter � 2012 The Geologists’ Association. Published by Else

doi:10.1016/j.pgeola.2012.01.002

refinements have been provided by numerous authors, notablyBristow (1862), Judd (1871), Meyer (1873), Reid and Strahan(1889), Strahan (1898), White (1921), Arkell (1947), Stewart(1978a, 1981a), Hesselbo and Allen (1991), Stewart et al. (1991),Radley (1994a) and Radley and Barker (1998a). The lithostrati-graphic nomenclature now in use (Figs. 5 and 6) was introduced byDaley and Stewart (1979). Chronostratigraphy has relied largely onpalynology (Hughes and Croxton, 1973; Hughes and McDougall,1990a,b; Hughes, 1994), ostracods (Anderson, 1967, 1985),magnetostratigraphy (Kerth and Hailwood, 1988) and fossil woodcarbon-isotope stratigraphy (Robinson and Hesselbo, 2004).Hesselbo and Allen (1991) provided a sequence-stratigraphicinterpretation of the basal Wealden at Mupe Bay, reconsidered byHesselbo (1998).

The first detailed account of Wealden sedimentology andpalaeoecology in the Wessex Sub-basin (Stewart, 1978a) focusedon the Isle of Wight sections, augmented by some data from Dorsetsites. Since then there has been a growing body of literatureconcerning sedimentology and palaeoenvironmental interpretationof these beds, notably Allen (1981), Stewart (1978b, 1981a,b, 1983),Selley and Stoneley (1987), Ruffell (1988), Hesselbo and Allen(1991), Stewart et al. (1991), Wach and Ruffell (1991), Radley(1994a,b,c, 2005, 2006, 2009), Harding and Allen (1995), Wimbledonet al. (1996), Hesselbo (1998), Radley and Barker (1998b, 2000a,b),Radley et al. (1998a,c), Wright et al. (2000), Jeans et al. (2001),

vier Ltd. All rights reserved.

http://dx.doi.org/10.1016/j.pgeola.2012.01.002

mailto:[email protected]

http://www.sciencedirect.com/science/journal/00167878

http://dx.doi.org/10.1016/j.pgeola.2012.01.002

Fig. 1. Outline geological map of the Isle of Wight, southern England, showing

principal Wealden (non-marine Lower Cretaceous) localities mentioned in the text

(Compton Bay–Brightstone Bay and Sandown Bay GCR sites). After Wright et al.

(2000, fig. 1).

J.D. Radley, P. Allen / Proceedings of the Geologists’ Association 123 (2012) 319–373320

Yoshida et al. (2001), Robinson et al. (2002), Jeans (2006) andSweetman and Insole (2010).

Palaeoclimatic studies have utilized several lines of evidence,including general sedimentation patterns (Stewart, 1978a), palaeo-pedology (Wright et al., 2000), clay mineralogy (Ruffell and Batten,1990; Ruffell and Garden, 1997; Hallam et al., 1991), tree-ringanalysis (Francis, 1987), plant morphology (Haworth et al., 2005;Haworth and McElwain, 2008), stable-isotope geochemistry(Robinson et al., 2002) and computer modelling (Haywood et al.,2004). Allen (1998) added to the body of data and provided aninterpretative review of the Purbeck–Wealden climates.

Occurrences of Wealden invertebrates have been summarizedfor example by Fitton (1836), Jones (1888), Reid and Strahan(1889), White (1921), Arkell (1947), Anderson (1967), Stewart(1978a, 1981a), Ruffell (1988), Stewart et al. (1991), Radley (1994a,1995, 2002), Twitchett (1995), Radley and Barker (1998b, 2000b)

Fig. 2. Location map for Geological Conservation Review sites in Dorset, south-

and Radley et al. (2006). Important palaeobotanical studies weremade for example by Alvin (1974), Hughes (1975), Oldham (1976),Alvin et al. (1981, 1994), and Collinson et al. (2000). Trace fossilswere documented by Goldring et al. (2005) and the derived fossilsby Radley (2005). The globally significant dinosaur faunas havebeen summarized by Mansel-Pleydell (1888) and Martill and Naish(2001) and the pterosaurs by Howse et al. (2001), Witton et al.(2009) and Sweetman and Martill (2010). Other reptiles aresummarized by Benton and Spencer (1995). Whilst this accountwas in press, the Palaeontological Association published a guide toEnglish Wealden fossils (Batten, 2011). This documents theWealden biota in great detail and mentions many of the sitesdocumented herein.

Detailed information on the Wealden succession has also beenfurnished by Geologists’ Association excursion reports (e.g.Hudleston, 1882; Morris et al., 1882; Holmes and Leighton,1892; Colenutt and Hooley, 1906, 1919; Hall, 1933; Arkell, 1934;Barnard, 1948; Daley and Stewart, 1979; Radley, 1994c).

Despite this long history of research, ongoing investigationscontinue to enhance the international significance of the WessexSub-basin as a record of Early Cretaceous sedimentation andpalaeoenvironmental change. Petroleum exploration over the lastfew decades has provided much impetus and support (Underhill,1998) and contributed significantly towards understanding thetectonic evolution of the region during the late Mesozoic.

3. Structural framework

The Wessex Sub-basin (Figs. 3 and 4) lies within and to thesouth of the east-west trending Isle of Wight–South Dorset zone ofstructural disturbance. This zone is dominated by the Isle of Wightand Isle of Purbeck monoclines and the associated Ridgeway–Abbotsbury fault complex (Arkell, 1947; House, 1961; Underhilland Paterson, 1998; Underhill and Stoneley, 1998; Underhill, 2002;Figs. 2 and 4). Deep-seated steeply dipping faults, which underliethese structures, are former growth faults. Downthrown to thesouth, they demarcate the northern margin of the Wessex Sub-basin as it was throughout Early Cretaceous times (Chadwick,1986; Karner et al., 1987; Hamblin et al., 1992; Butler, 1998;Underhill, 2002; Figs. 4, 7 and 8). Evidence for contemporaneous

west England (Wessex Sub-basin), showing principal geological structures.

Fig. 3. Non-marine Early Cretaceous basins and source massifs in north-west Europe, and outline of major stratigraphic units. After Allen (1998, fig. 1) 1. Dorset

(palaeolatitude c. 348N) 2. Swindon, Wiltshire 3. Hartwell, Buckinghamshire 4. Shepherd’s Chine, Isle of Wight 5. Sandown Bay, Isle of Wight 6. West Hoathly, West Sussex

(palaeolatitude c. 298N) 7. Mussey, France.

J.D. Radley, P. Allen / Proceedings of the Geologists’ Association 123 (2012) 319–373 321

erosion and movement on them in Wealden times, seen at severalsites, includes influxes of locally derived detritus (Radley, 1993a,2005; Radley et al., 1998c; Martill and Barker, 2000), hydrocarbonpalaeoseeps (Wimbledon et al., 1996) and marked lateral thicknessvariations (Radley and Barker, 1998a; Underhill and Paterson,1998; Underhill, 2002). Selley and Stoneley (1987) and Underhilland Stoneley (1998) suggested the presence of a rollover anticlineon the downthrown side of the Purbeck fault, that generatedgravity slide structures in the basal Cretaceous Purbeck Groupstrata and confined Wealden deposition in the South Dorset area atleast, to a narrow east-west valley (Figs. 4 and 7).

Sites in south Dorset (Fig. 2) are close to the former easternmargin of the Cornubian massif (Cornubia), thought to lie near theDorset–Devon border (Figs. 3 and 9). Significantly, the EarlyCretaceous succession thins towards this area and is locally rich inCornubian detritus (Allen, 1972, 1991; McMahon and Turner,1998). Coarse-grained materials amongst the Wealden stratasuggest that the eastern part of Cornubia was partly an upland offolded Carboniferous rocks, flanked by a Permian–Triassic red-bedand Jurassic cover (Allen, 1981; Fig. 9). The Early Cretaceoussediments also thin southwards towards the Central Channel High,at the southern, offshore margin of the Wessex Sub-basin(Hamblin et al., 1992; Ainsworth et al., 1998; Fig. 4).

The structures seen today have contributed greatly to the valueof the area for geological study. Thus around Lulworth Cove,Dorset, steep dips on the northern limb of the Purbeck monocline(Fig. 2) enable inspection of the complete Wealden succession overdistances of just a few hundred metres. On the Isle of Wight (Fig. 1),where the strata are less disturbed, the extensive coastal sectionsfacilitate detailed study of lateral facies variations in the complexalluvial strata.

4. Lithostratigraphy

Current terminology for the Wealden Group follows extensivesedimentological and palaeoecological investigations of theCompton Bay–Brighstone Bay site on the Isle of Wight (Stewart,1978a, 1981a,b, 1983; Fig. 6), and is applicable to Dorset. TheWessex Formation is mainly oxidized alluvium, previously namedWealden Marls (White, 1921) and Variegated Marls and Sand-stones (Arkell, 1947). The term Vectis Formation replacesWealden Shales (e.g. Reid and Strahan, 1889; White, 1921; Arkell,1947) for the relatively fossiliferous uppermost Wealden on theIsle of Wight and in eastern Purbeck. Nowell (1997, 1998a)subdivided the Wessex Formation of the Lulworth area into fivelithostratigraphic units. This scheme is apparently of limited use,given the rapid lateral facies changes shown by the strata (Arkell,1947; Allen and Wimbledon, 1991) and discrepancies within theproposed definitions and characters of the subdivisions (Radley,1998).

5. Chronostratigraphy

The non-marine (alluvial) Wessex Formation has not providedfirm links with either Tethyan or Boreal marine successions,though volcanigenic beds discovered in the underlying UpperPurbeck Beds have been tentatively correlated with bentoniteswithin the marine Ryazanian of the Yorkshire coast, north-eastEngland (Jeans et al., 2005). The palynological results (Hughes andMcDougall, 1990a; Hughes, 1994) suggest that the Valanginian–Hauterivian boundary lies in the lower part of the WessexFormation and evidence from sparse molluscan faunas at theSwanage Bay site is consistent with this.

Fig. 4. Map illustrating distribution of Wealden (non-marine Lower Cretaceous) alluvial lithofacies in the Weald and Wessex sub-basins, southern England (after Hawkes

et al., 1998, fig. 25).

Fig. 5. Chronstratigraphic interpretation of Wealden strata (Valanginian up to Aptian) in the Wessex Sub-basin, southern England. Incorporating data from Allen and

Wimbledon (1991) and Callomon and Cope (1995, fig. 34).


Fig. 6. Outline stratigraphy of the Wealden Group (non-marine Lower Cretaceous)

on the Isle of Wight, southern England (after Radley and Barker, 1998a, fig. 1).


The Coarse Quartz Grit of Dorset (Fig. 5) is presently the onlywidespread horizon known (Allen, 1989; Allen and Wimbledon,1991; Radley, 1998; British Geological Survey, 2000; Robinson andHesselbo, 2004). It has yielded pollen indicative of the earliestBarremian, though fossil wood carbon-isotope stratigraphy points

Fig. 7. Sub-Albian (Lower Cretaceous) subcrop map, Isle of Wight, Wessex Sub-basin, so

echelon faults downthrowing to the south which define the northern border of the Wess

accumulated. To the north, on the hanging wall, Jurassic strata were exposed through mu

Middle Jurassic Great Oolite. Although the palaeogeology shown here had undergone ero

reasonable impression of the outcrop during Vectis Formation (latest Wealden) times.

to an older, mid to late Hauterivian age (Robinson and Hesselbo,2004). The pebbly detritus of the Coarse Quartz Grit is almostwholly Cornubian and suggests uplift and heavy rainstorms on themassif (Figs. 3 and 9). Events of this type may prove recognizable atother horizons in the Wessex Formation, and thereby assist incorrelation with the Weald Sub-basin of south-east England.

The lower part of the Vectis Formation on the Isle of Wightyields putative Upper Barremian charophytes (Feist et al., 1995)and magnetostratigraphic evidence suggests that the highest bedsare of early Aptian age (Kerth and Hailwood, 1988; Figs. 3, 5 and 6).This is supported by early Aptian fissicostatus biozone ammonitesin the basal beds of the Lower Greensand Group (Casey, 1961;Simpson, 1985), which follows the Vectis Formation with littleapparent break. The Vectis Formation wedges out westwards intoDorset where the highest beds of the Wessex Formation arefeasibly of early Aptian age (Allen and Wimbledon, 1991; Fig. 5).

Evidence from palynomorphs (Hughes, 1958), ostracods(Anderson, 1967, 1985) and molluscs (Morter, 1978; Radleyet al., 2006) indicates that the Vectis Formation broadly correlateswith the uppermost Weald Clay of the Weald Sub-basin. Stormcoquinas in the highest beds are correlatable across the Isle ofWight (Fig. 10) and presumably isochronous (Radley and Barker,2000a). Like the inferred Cornubian flood deposits (Allen, 1989,1991), these could also ultimately prove detectable beyondWessex.

6. Palaeobiology

The Wealden strata yield remains and traces of plants andanimals that inhabited a range of alluvial, lacustrine and coastallagoonal environments, influenced by warm to hot climates of

uthern England. Here, the Purbeck–Isle of Wight structure is dominated by two en

ex Sub-basin in which a thick Wealden (Valanginian up to early Aptian) succession

ch of the Lower Cretaceous; a pericline plunging to the north-west exposed a core of

sion for approximately ten million years since the early Aptian, this map still gives a

After Radley et al. (1998c, fig. 2).

Fig. 8. Palaeoenvironmental model for the Isle of Wight during upper Wessex Formation (Barremian) times. In the north, the margin of the Wessex Sub-basin is represented by

an upfaulted terrain of Upper Jurassic strata (Martill and Naish (2001, fig. 2.11).

Reproduced by permission of the Palaeontological Association.

Fig. 9. Model for Wealden arenaceous formations in the Wessex–Weald Basin, southern England, including speculative palaeogeological maps of source massifs. The Cornubian

massif (Cornubia) lies to the west of the basin; the London massif (Londinia) to the north-east and the Armorican massif (Armorica) to the south (after Allen, 1981, fig. 8).


Fig. 10. Stratigraphic distribution and correlation of limestone beds (C1–3, A1–4, S1–4) in the Shepherd’s Chine Member (upper Vectis Formation) of the Isle of Wight,

southern England (after Radley and Barker, 2000a, fig. 3).


Mediterranean aspect. Cornubian uplift in late Berriasian timesculminated in the spread of river systems across the Upper Purbecklacustrine complex (Allen and Wimbledon, 1991; Batten, 2002),bringing in large quantities of mud and sand that now constitutethe Wessex Formation. Dinosaurs, turtles, crocodiles, mammals,fishes, pond mussels, insects and other animals inhabited distalmeanderplains in the Swanage–Isle of Wight region. Sandy, dryelevations favoured establishment of ferns and trees. Overhead,pterosaurs and possibly birds would have been evident (Sweetmanand Insole, 2010, fig. 15). Brackish-water molluscs, ostracods andother invertebrates colonized the Swanage–Isle of Wight region inlate Barremian times, as the Vectis lagoonal transgressionforeshadowed establishment of fully marine environments duringthe early Aptian. Fish, including many sharks, swum in the muddylagoonal shallows and scavenging dinosaurs patrolled the shores.

7. Salinities

Amongst the molluscan faunas (Fig. 11), unionoid bivalves showgreater diversity in the underlying alluvial Wessex Formation thanin the overlying lacustrine–lagoonal Vectis Formation, attesting tostable freshwater habitats. Quantification of Vectis Formationsalinity fluctuations has been attempted using molluscs (Ruffell,1988; Stewart et al., 1991; Radley and Barker, 1998a,b; Radley et al.,2006), ostracods (Jones, 1959; Anderson, 1985; Wilkinson, 2008),palynomorphs (Batten, 1982; Harding and Allen, 1995), foraminifera(Radley, 1995), ichnofossils (Stewart, 1978b; Goldring et al., 2005)and carbon isotopes (Allen and Keith, 1965; Allen et al., 1973).

The Vectis Formation indicates re-establishment of coastallagoonal environments. Low-diversity associations of viviparidgastropods and unionoid bivalves are taken to signify freshwater orat most, low oligohaline conditions. As in the Weald Clay of theWeald Sub-basin (Allen, 1975), the strongly euryhaline bivalveFilosina characterizes fluctuating oligohaline–mesohaline regimes(Radley and Barker, 1998b; Radley et al., 2006; Fig. 11). Towardsthe lower end of the salinity range Filosina accompanies viviparidgastropods. In the ‘brackish-marine’ horizons near the top of theVectis Formation Filosina is associated with mesohaline and

brachyhaline taxa such as Praeexogyra, Cuneocorbula, Nemocardium

(bivalves), and Procerithium and Paraglauconia (gastropods). Thesame salinities are broadly reflected by associated palynomorphs(Batten, 1982) and carbon isotopes (Allen et al., 1973). Thepalaeoenvironmental significance of the ostracods is less clear,given uncertainities regarding their ecology (Horne, 1995).

8. Sea-level changes

The Wessex Formation is developed entirely in non-marinefacies, precluding direct detection of contemporaneous sea-levelchange. The base of the overlying Vectis Formation possibly youngsto the west across the northern part of the Wessex Sub-basin(Fig. 5), marking the late Barremian spread of a shallow coastallagoon over the floodplains. This could be explained by sea-levelrise prior to the main Aptian (Lower Greensand) transgression(Allen, 1975; Ruffell, 1988; McMahon and Turner, 1998), althoughmud-cracked surfaces and dinosaur trackways through much ofthe succession (Radley et al., 1998a) indicate little attendantdeepening. Thus the Vectis Formation recalls the Wadhurst,Grinstead and Weald clays of the Weald Sub-basin, attributablelargely or wholly to massif downfaulting, consequential lowerrainfall and partial destruction of coastal barriers (Allen, 1975,1981). Nevertheless, the lower of two ‘brackish-marine’ horizonsin the upper part of the Vectis Formation (Shepherd’s ChineMember) on the Isle of Wight includes a Diplocraterion-burrowedironstone (Stewart et al., 1991; Radley, 1994b; Fig. 12), suggestinga marine flooding event (Goldring et al., 2005). Lying just below theerosive base of the marine Perna Beds Member (Lower Greensand),the highest brackish-marine horizon comprises dark shellymudstone, suggesting a dysaerobic low-energy offshore setting.Minor sea-level fluctuations may therefore have foreshadowed themain Lower Greensand marine transgression.

9. Summary of interpretation

Greater quantities of mud, sand, iron, reworked Jurassicbioclasts and plant debris amongst the Upper Purbeck lacustrine

Fig. 11. Wealden molluscs from the Sandown Bay and Brighstone Bay GCR sites, Isle of Wight, southern England. (a) Margaritifera (Pseudunio) valdensis from plant debris bed

approximately 1–2 m above the Sudmoor Point Sandstone, Wessex Formation. Approximately 600 m north-west of Chilton Chine. Scale bar equals 2 cm. (b) Viviparus

fluviorum from sandstone unit in lower part of exposed Wessex Formation. Sandown Bay. Scale bar equals 0.5 cm. (c) Unio cf. elongata from plant debris bed approximately

4 m below top of the Wessex Formation. Sandown Bay. Scale bar equals 1 cm. (d) Unio cf. turgidula from lignitic interval approximately 11–17 m below top of the Wessex

Formation. Sandown Bay. Scale bar equals 0.5 cm. (e) Paraglauconia fittoni from shelly limestone approximately 11 m below top of the Shepherd’s Chine Member (Vectis

Formation). Foreshore south-east of Shepherd’s Chine, Brighstone Bay. Scale bar equals 0.5 cm. (f) Viviparus infracretacicus from the Cowleaze Chine Member (Vectis

Formation). Near Barnes High, Brighstone Bay. Scale bar equals 0.25 cm. (g) Filosina gregaria from the Cowleaze Chine Member (Vectis Formation). Sandown Bay. Scale bar

equals 1 cm. (h) Praeexogyra cf. distorta from shelly limestone approximately 10 m below top of the Shepherd’s Chine Member (Vectis Formation). Sandown Bay. Scale bar

equals 1 cm. All specimens are held in the collection of Dinosaur Isle, Sandown, Isle of Wight

(Radley and Barker, 1998b, fig. 3; reproduced by the permission of Elsevier).


Fig. 13. Model for Wealden (non-marine Lower Cretaceous) argillaceous formations

in the Wessex–Weald Basin, southern England Asterisk (lower right) indicates

inferred direction of possible Tethyan marine influxes (After Allen, 1981, fig. 11).

Fig. 12. Position of principal marker beds and horizons in the Vectis Formation

(Barremian up to early Aptian) of Compton Bay and correlation with the Atherfield

‘type’ section (Compton Bay–Brighstone Bay GCR site, Isle of Wight). After Radley

and Barker (1998a, fig. 6).


carbonates and mudstones indicate initial uplift of Cornubia andthe Dorset–Isle of Wight structure in Berriasian times (Figs. 3, 4, 7–9), first hinted at by the Middle Purbeck kaolinite rise (Allen andWimbledon, 1991). The main bulk of Cornubian sand did not arriveuntil Wealden times. Following pronounced late Berriasian or earlyValanginian upfaulting of Cornubia and intrabasinal structures, theWessex Formation built up as a pile of sandy and pebblybraidplains, passing eastwards into the meanderplains of the Isleof Wight (Sandown Bay and Compton Bay–Brighstone Bay sites)that were dominated by suspended-load streams (Stewart, 1978a,1981a,b; Fig. 8). These distal lithofacies presumably drained eithernorthwards to the Boreal sea or southwards into Tethys (Figs. 3 and13). The Purbeck–Isle of Wight fault belt, still delimiting thenorthern margin of the depocentre (Figs. 4, 7 and 8), was theprobable source of scattered Jurassic debris that was sometimesrecycled as dinosaur gastroliths (Martill and Barker, 2000; Martill

and Naish, 2001; Radley, 2005). The fault-belt was intimatelylinked with the contemporary oil-seep on the Mupe Bay floodplain(Mupe Bay–Worbarrow Bay site; Fig. 2).

Breaks in the muddy channel fills of the meandering riversystems are evidenced by erosion surfaces, desiccation cracks anddinosaur tracks. These punctuated fluctuations in discharge,generating splays and overbank floods. Closer to the Cornubianmargin they left unembanked braided channels (e.g. Durdle Doorsite), some filled with pebbly sand (e.g. Coarse Quartz Grit).Distally, these appear to pass into horizons such as the ‘Pine Raft’ ofthe Isle of Wight and ill-sorted accumulations of forest treefragments, reptile bones, freshwater shells, intraclasts and rarerextrabasinal debris, some of which settled in partially stagnantponds to form plant debris beds (Insole and Hutt, 1994; Radley andBarker, 2000b; Sweetman and Insole, 2010). The more permanentponds and lakes may have functioned as dry-season refuges for arange of animals. A warm to hot, wet ‘Mediterranean’ climate withprolonged dry spells is indicated by abundant fusain, clay-mineralogical evidence for intensive leaching at source, plants ofwarm-temperate to subtropical aspect (some xeromorphic) andabundant turtle and crocodile remains (Allen, 1998). Betweenfloods, the alluvium underwent extensive pedogenesis, resulting insurface-water gley soils in seasonally waterlogged areas, and redvertisols where slight elevations or other factors controlleddrainage conditions (Wright et al., 2000).

First appearing in the Isle of Wight, the Vectis Formationprovides palaeontological and sedimentological evidence for lateBarremian transgression of lagoonal facies from the Weald Sub-basin of south-east England, either around or through the Purbeck–Isle of Wight structure. North-South trending barrier islands arepostulated in eastern Wight (Stewart et al., 1991) protecting theVectis lagoon from marine invasions via the Paris Basin and/orSouthwestern Approaches (Allen, 1989; Fig. 3).

Lagoon-margin facies at the base of the Vectis Formation inwestern Wight (Compton Bay–Brighstone Bay site) record afluctuating, muddy, plant-colonized shoreline at first. This wasfrequently visited by dinosaurs (Radley et al., 1998a). Thereafter,uniform dysaerobic muds spread across the whole area of the Isleof Wight (Cowleaze Chine Member; Fig. 6), introducing low-diversity freshwater-oligohaline ostracod and molluscan faunas.Small-scale fining-upward cycles in the muds were probablyproduced by distal deltaic advance and retreat (Stewart et al.,1991). The overlying Barnes High Sandstone Member probably


marks eastward deltaic progradation into the lagoon (Stewart,1981a; Stewart et al., 1991) although Yoshida et al. (2001)proposed an estuarine origin.

After abandonment, the deposition of partly dysaerobic, cyclic,mud and silt resumed (Shepherd’s Chine Member; Fig. 6) and

Fig. 14. Vertical section through the Wessex Formation (Barremian) at Yaverland, Sa

spread further west across the sub-basin (Allen and Wimbledon,1991; Ruffell and Batten, 1994). The higher part of the Shepherd’sChine Member includes storm scours, storm-deposited coquinas,mudcracked and dinosaur-trampled horizons, quasi-marine colo-nization surfaces and influxes of brachyhaline molluscs (Arkell,

ndown Bay, Isle of Wight (Sandown Bay GCR site). After Radley (1994a, fig. 2).


1947; Wach and Ruffell, 1991; Radley and Barker, 1998b). Thesefeatures point to a culminating Wealden regime of broad mudflatsflooded by frequent wind-induced surges; storm washovers fromthe encroaching sea and perhaps phases of eustatic sea-level rise(Wach and Ruffell, 1991; Radley et al., 1998a). As in the Weald Sub-basin, there is palaeontological evidence for both Tethyan andBoreal influences (Allen, 1989; Harding and Allen, 1995; Radleyet al., 2006; Fig. 13).

The continuing influence of the Purbeck–Isle of Wight structurein the east Wight region (Figs. 4, 7 and 8) is borne out by abundantOxfordian–Portlandian (Late Jurassic) fossils in the uppermostbeds of the Shepherd’s Chine Member immediately south of theinferred footwall (Sandown Bay site; Radley et al., 1998c). Furthertransgression during early Aptian (fissicostatus biozone) times ledto reworking of the highest part of the Vectis Formation andestablishment of fully marine conditions and faunas (Perna BedsMember at the base of the Lower Greensand Group; Casey, 1961;Simpson, 1985; Fig. 5). A warm to hot, periodically wet climatethroughout Vectis Formation times is indicated by flood-depositedinfluxes of burnt plant debris (Harris, 1981; Allen, 1998; Collinsonet al., 2000), and a vertebrate fauna that includes commoncrocodile remains (Benton and Spencer, 1995).

10. Site accounts

10.1. Sandown Bay, Isle of Wight (SZ 611849–SZ 621853)

10.1.1. Introduction

Sections here expose the uppermost Wessex Formation and thewhole of the Vectis Formation on the south-east coast of the Isle of

Fig. 15. Foreshore exposures in the Wessex Formation (Barremian) at Yaverland, Sandow

in the foreground is approximately 2 m wide and comprises deformed silty mudstones

Wight. They run north-eastwards for about 1.25 km on the north-east limb of the Sandown Anticline, disappearing beneath theLower Greensand at Red Cliff, about 1 km south of the Isle of WightMonocline (Figs. 1 and 7). These are the easternmost exposures ofWealden strata in the Wessex Sub-basin, and are important fordemonstrating late Wealden palaeoenvironments and palaeoecol-ogy, and the influence of the Isle of Wight–Portsdown High ondeposition.

The Wealden was initially noted here by Webster (1816),Conybeare and Phillips (1822), Sedgwick (1822), Mantell (1827)and Buckland and De la Beche (1836). Overall stratigraphy wasestablished by Fitton (1824, 1836), Mantell (1833, 1846, 1854),Wilkins (1859), Bristow (1862), Judd (1871), Norman (1887), Reidand Strahan (1889), White (1921), Stewart (1978a) and Radley(1994a). The invertebrate macropalaeontology and palaeobotanyhas been documented for example by Mantell (1844a, 1848a,b,1854), White (1921), Jackson (1930, 1933), Casey (1955), Oldham(1976), Radley (1994a), Twitchett (1995) and Radley and Barker(2000b), and the ichnology by Goldring et al. (2005 and referencestherein). Invertebrate microfauna and microflora were documen-ted for example by Sowerby (1836), Jones (1878, 1885, 1888),Kilenyi and Neale (1978), Anderson (1967, 1985), Batten (1974),Batten and Lister (1988a,b), Hughes (1994), Hughes and McDougall(1990a,b), Radley (1994b, 1995), Harding and Allen (1995) andWilkinson (2002, 2008). Vertebrate faunas have been documentedfor example by Patterson (1966), Radley (1994a), Benton andSpencer (1995), Dineley and Metcalf (1999), Martill and Naish(2001), Sweetman (2006, 2008), Sweetman and Underwood (2006)and Sweetman and Martill (2010). Diagenesis of dinosaur boneswas documented by Barker et al. (1997a). Sedimentological data

n Bay, Isle of Wight (Sandown Bay GCR site), cleared by storms during 1992. Outcrop

and thin sands, representing part of a dinosaur trampled (dinoturbated) surface.


have been provided by Groves (1931), Allen (1972, 1975, 1998),Prior (1993), Ruffell and Garden (1997), Yoshida et al. (2001) andSweetman and Insole (2010). Ruffell (1988), Stewart et al. (1991),Wach and Ruffell (1991), Radley (1994a,b,c, 1995, 1997a, 2009),Radley et al. (1998c), Radley and Barker (2000a,b), Gale (2000),Watson et al. (2001) and Sweetman and Insole (2010) have furtherdescribed and interpreted lithologies, faunas, floras and palaeoen-vironments. The palaeoecology has been studied by Allen andKeith (1965), Allen et al. (1973), Radley (1993b, 1994a, 1995,1997a) and Radley and Barker (1998b, 2000b). Radley (2005)summarized occurrences of derived fossils. Kerth and Hailwood(1988) carried out an important study of the magnetostratigraphyof the Vectis Formation. Clay mineralogy was studied for exampleby Jeans et al. (2001) and Jeans (2006). The overall geology hasbeen summarized by Daley and Insole (1984), Insole et al. (1998)and noted by Radley (2006). The site has been popular as adestination for geological field meetings for over 100 years (Morriset al., 1882; Herries, 1910; Hall, 1933; Waite, 1964; Barnard, 1948;Ruffell and Harvey, 1993; Radley, 1994c). Martill and Naish (2001)published colour photographs of the section.

10.1.2. Description

The strata dip at around 5–88 north-east at the south-west endof the section, steepening north-eastwards to approximately 208.Additionally, a structurally disturbed, steeply dipping section ofthe uppermost Vectis Formation has been recorded beneath theLower Greensand within the toe of Red Cliff landslip (SZ 622853).

Fig. 16. Part of point-bar sequence of mudstones and sandstones displaying lateral accre

Photograph courtesy of Trevor Price, Dinosaur Isle.

10.1.2.1. Wessex Formation. The highest 50 m of the WessexFormation are traceable for approximately 900 m between SZ611849 and SZ 618853 (Figs. 14 and 15), dominated by massive,varicoloured to red, slickensided mudstones with rootlet traces.The mudstones are dominated by illite and kaolinite (Jeans, 2006).The rare dinosaur bones within oxidized mudstone units (Radley,1994a,c) are internally mineralized with barite, witherite andapatite (Barker et al., 1997a). Sandstones and plant debris beds alsooccur and palynological samples yield monosulcate pollen(Hughes, 1994). The lowest few metres comprise sandstones(some ripple marked) interbedded with mudstones, occasionallyrevealed from beneath beach sand on the shore below theYaverland Car Park. Amongst the mudstones, a thin grey-colouredunit furnished the first conchostracans known from the Wealden ofthe Wessex Sub-basin (D.M. Martill, personal communication).Approximately 10 m above the base, interbedded oxidizedmudstones and thin ferruginous sandstones display much soft-sediment deformation, some recognizable as tracks of Iguanodon,ankylosaurid or sauropod and theropod dinosaurs (Radley, 1994a,1997a).

A higher calcite-cemented sandstone (Fig. 14), no longerexposed, is packed with broken to complete Viviparus fluviorum

(Fig. 11), neomorphically replaced by calcite and preserving algalor fungal borings. Unidentifiable ostracods also occur in this bed.The sandstone is overlain by fissured, vertically striped and ligniticmudstones (plant debris beds). The latter yield rounded, polishedclasts of quartz and silicified Jurassic limestone, probably dinosaur

tion surfaces. Wessex Formation (Barremian), Sandown Bay GCR site, Isle of Wight.


gastroliths. In the main cliff section, the supervening 3–3.5 msuccession of interbedded sand and oxidized mudstone (Fig. 16,also see Martill and Naish, 2001, colour plates 4 and 5) displaysdepositional dips towards the north-east and locally commenceswith a layer of lignitic mud-clast conglomerate. Soft-sedimentdeformation is common throughout, some recognizable asIguanodon and theropod dinosaur tracks (Fig. 17). Beaconites

burrows also occur. Varicoloured mudstones (c. 20 m thick)overlying this unit disclose probable rootlet traces, more soft-sediment deformation, pseudoanticlinal structures, Iguanodon

tracks and thin plant debris beds. Examples of the latter, possiblyat this level, have yielded fusain fragments, megaspores, seeds,conifer leaves, amber fragments, charophytes, termite coprolitesand ostracods (Cypridea sp.?, Lycopterocypris sp.) (I.C. Harding,personal communication). Red and grey mudstones about 19 mbelow the top of the Wessex succession have yielded a gastrolith ofsilicified wood (Araucarioxylon) of Purbeck (Berriasian) or possiblyWealden age (J.E. Francis, personal communication). These bedsalso preserve pseudoanticlinal structures.

An interval of grey, silty, lignitic mudstones with sideriticnodules occurs approximately 11–17 m below the top of theformation (Fig. 14; also see Martill and Naish, 2001, colour plates 2and 3). Interbedded intraclastic, sideritic plant debris beds (lessthan 1 m thick) within this interval are richly fossiliferous. They arepacked with flattened, partly pyritized, variably oriented lignitefragments (some fusainized), cones, fern (Weichselia) and silicifiedTempskya (tree-fern) fragments. Unionoid bivalves are preservedas aragonitic compressions and sideritic or pyritic moulds (Fig. 11)and include taxa resembling ‘Unio’ elongata, ‘Unio’ cornueliana and‘Unio’ scutella. Some preserve ligaments and/or phosphatized gill

Fig. 17. Iguanodontid dinosaur footcast within a trampled surface of Wessex Formation

supports and umbonal etching (Radley and Barker, 2000b). Oneinternal mould has revealed surficial traces of probable gastropodeggs that would have encrusted the shell interior (also seeCompton Bay–Brighstone Bay account). These plant debris bedsalso furnished the holotype and several paratypes of thetrigonioidid bivalve Subnippononaia fordi (Barker et al., 1997b;Delvene and Munt, 2011). The rare gastropods comprise Viviparus

fluviorum and Prophysa cf. bristovii. Predominantly disarticulatedvertebrate remains include dinosaur bones and teeth (mainly ofIguanodon); also crocodile, turtle, pterosaur and fish (Lepidotes)remains (White, 1921; Radley, 1994a; Benton and Spencer, 1995;Sweetman and Martill, 2010). Larger bones have been internallymineralized by barite, pyrite, chalcopyrite and siderite. A gastrolithcomprising a silicified pebble of Tempskya has been found (M.Munt, personal communication). Coprolites also occur.

This fossiliferous interval is capped by varicoloured mudstones(c. 3 m thick). An Iguanodon footcast has been noted amongstirregularly shaped sandstone lenticles near the base, and the upperpart encloses calcareous nodules. The underside of the overlyingcross-laminated sandstone (up to c. 1 m thick) similarly displayslarge, distorted Iguanodon footcasts, occasionally seen as looseblocks on the shore. The remaining Wessex beds are massivevaricoloured mudstones (locally intraclastic and barite-veined;Fig. 14), with an intercalated plant debris bed. The latter hasyielded abundant Iguanodon remains (J.D. Radley, personalobservations), bones of amphibians and lizards, mammal teeth,planorbid gastropods and charophytes (S. Sweetman, personalcommunication; Sweetman, 2006, 2008), neoselachian shark teethattributed to Palaeoscyllium (Sweetman and Underwood, 2006)and a possible pterosaur phalanx (Sweetman and Martill, 2010).

(Barremian) mudstones, Sandown Bay GCR site, Isle of Wight. Pen provides scale.

Fig. 18. Vertical section through the Cowleaze Chine Member (lower Vectis

Formation). Sandown Bay GCR site, Isle of Wight.


Pseudoanticlinal structures are evident in grey and purplemudstones approximately 3 m below the base of the VectisFormation. A gastrolith consisting of late Precambrian tourmali-nized quartzite-breccia (White, 1921; Allen, 1975) is thought to befrom this part of the succession (Radley, 1994a); a radiometric dateof c. 308 ma from the gastrolith suggests Hercynian deformation(Allen, 1975). Groves (1931) recorded abundant Armoricandetritus from the ‘Weald Clay’ of Sandown. This probably refersto the Wessex Formation, because at that time the overlyingargillaceous Vectis Formation was already being referred togenerally as ‘Wealden Shales’ (e.g. White, 1921). Jackson (1933)recorded tubers of the horsetail Equisetum burchardtii from anunknown level of the Wessex Formation but this record remainsunconfirmed.

10.1.2.2. Vectis Formation. The Vectis Formation (Figs. 6 and 10) isapproximately 45 m thick and lies on an eroded and burrowedsurface of the Wessex beds (Fig. 14). Ruffell and Garden (1997)recorded kaolinite abundances of around 40% from the VectisFormation at this site, but did not specify the sample levels.Kaolinite recorded by Jeans (2006) was appreciably lower, at 27%.The basal few centimetres of the Cowleaze Chine Member(approximately 11 m thick; Fig. 18) comprise muddy chamosite‘grit’ with scattered bivalves (Filosina cf. gregaria) and ostracods(Theriosynoecum fittoni). This is overlain by blocky grey mudstone(0.5 m) with aragonitic Filosina. The suncracked upper surface ofthis unit is infilled and overlain by a thin mud-clast breccia yieldingabundant low salinity dinocysts (I.C. Harding, personal communi-cation), partly articulated fish, scattered fish scales and occasionalostracods (‘intraclastic fish bed’ of Fig. 18).

The overlying few metres of strata are mainly grey-colouredmudstones containing pavements of aragonitic Filosina gregaria,Viviparus infracretacicus, Viviparus fluviorum, sporadic planorbi-form gastropods (possibly Planorbis sp.), ostracods, fish debris andinsect remains. Filosina shells (Fig. 11) preserve ligaments (Casey,1955) and umbonal dissolution scars (Radley and Barker, 1998b). Atabular clay-ironstone bed near the middle of the member (Fig. 18)is packed with mouldic Filosina gregaria, small unionoid bivalves(possibly ‘Unio’ compressus), Viviparus infracretacicus, and ostra-cods (White, 1921; Radley, 1994c). Upward-coarsening sandymudstones occur in the upper part of the member. Palynologicalassemblages from the member include monosulcate pollen(Hughes, 1994). Pale grey mudstones with siltstone lenticlesapproximately 0.5–1 m below the overlying Barnes High Sand-stone Member have revealed a further polygonally suncrackedsurface, infilled by darker slickensided mudstones with scatteredlignite fragments.

The gradationally based Barnes High Sandstone (c. 2.5 m thick;Fig. 10) coarsens up from interbedded mudstones and thinlenticular sandstones into flaser-bedded and ultimately troughcross-bedded ferruginous sandstones. Clay intraclasts (Ruffell,1988) and coarse quartz sandstones occur within the highest partof the member. Some of the latter display symmetrically rippledsurfaces (crests trending north-west/south-east) and one hasyielded a worn fragment of a Jurassic ammonite (M.J. Barker,personal communication). Rippled finer sandstones and Planolites-burrowed units also occur.

The overlying Shepherd’s Chine Member (c. 30 m thick; Fig. 19)is dominated by shaly and blocky grey mudstones, and cross-laminated and bioturbated fine sandstones. Clay-ironstones andcoarser sandstones occur in the lower beds. Well-developedpavements of gastropods, bivalves, ostracods and fish debris firstappear approximately 11 m above the base and thereafter atintervals to the top. Additional to taxa noted elsewhere in thisaccount, Anderson (1967, 1985) recorded the ostracods Cypridea

valdensis, Cypridea bispinosa, Cypridea insulae, Theriosynoecum

fittoni, Mantelliana mantelli and the lectotype of Cypridea spinigera

from these beds (also see Wilkinson, 2008). Dinocysts includeholotypes of Australisphaera longicornis and Microdinium? fibratum

(Batten and Lister, 1988b; D.J. Batten, personal communication).Fining-upward cycles (up to c. 1 m thick) are developed at some

levels. They grade up from lenticular trough cross-laminated finesandstones and fine sandstone gutter fills, through lenticular-bedded sands, silts and mudstones to dark grey mudstones and

Fig. 19. Vertical section through the Shepherd’s Chine Member (upper Vectis Formation). Sandown Bay GCR site, Isle of Wight.


shales. Fine sandstone gutter casts (oriented mainly north-south;Wach and Ruffell, 1991) yield fish debris and beetle, bug, fly,cockroach (Radley, 1994c; Twitchett, 1995) and pterosaur remains(Sweetman and Martill, 2010) and additionally display a variety ofburrow forms. Macroscopic plant debris occurs throughout themember.

Laterally persistent, sharp-based, ferroan calcite-cementedshelly limestone beds (‘coquinas’, normally less than 0.1 m thick)occur in the upper part of the member (Figs. 10, 19 and 20), mostcommonly dominated by small bivalves (Filosina gregaria) orgastropods (Viviparus infracretacicus). Palynological samples from

the 150 mm shale interval above the lowest limestone (c. 20 mbelow the top of the formation) yield wood and plant cuticlefragments, dinocysts (principally Vesperopsis fragilis and Corculo-

dinium uniconicum), spherical acritarchs, algae (e.g. Botryococcus,Scenedesmus and Tetraedron spp.), pteridophytic spores (e.g.Pilosisporites, Cicatricosisporites), gymnospermous pollen (includ-ing Classopollis) and rare columellate–tectate pollen (Harding andAllen, 1995). Ostracods within the lower and higher parts of thisinterval are Cypridea fasciata, Cypridea spinigera and darwinulids.The middle part is characterized by Cypridea fasciata, coincidingwith peak dinocyst abundances.

Fig. 20. Cross section through shelly limestone bed dominated by predominantly disarticulated, variably oriented bivalves (Filosina). Upper and lower surfaces of bed bear

fibrous calcite overgrowths. Shaly mudstone occurs above and below. Shepherd’s Chine Member (upper Vectis Formation), Sandown Bay GCR site, Isle of Wight.


The supervening 10 m interval is dominated by laminatedmudstones with cross-laminated and burrow-mottled siltstoneand fine sandstone lenticles, as well as gutter casts and ostracodshell beds. These are overlain by a muddy limestone (c. 80 mmthick) containing oysters (Praeexogyra cf. distorta, Fig. 11), rarerFilosina and small gastropods (possibly Procerithium). There thenfollows another mudstone-dominated interval (c. 5 m), enclosing

Fig. 21. Paranotacythere inversa: a brackish-marine ostracod from the upper Shepherd’s

courtesy of David Horne, Queen Mary, University of London). Scale bar = 200 mm.

tabular lenses of Diplocraterion-burrowed clay-ironstone (up to30 mm thick) just above the base (Fig. 19). The ironstone iscapped by a layer of disarticulated Filosina and Praeexogyra. Theassociated mudstones yield agglutinated foraminifera (Ammo-

baculites obliquus), ostracods (Paranotacythere inversa; Fig. 21),the bivalve Cuneocorbula cf. arkelli and small cerithiaceangastropods.

Chine Member (upper Vectis Formation) of the Sandown Bay GCR site. (Photograph

Fig. 22. Derived Upper Jurassic (Oxfordian) echinoid radiole (Plegiocidaris

florigemma) from the Shepherd’s Chine Member (upper Vectis Formation) of the

Sandown Bay GCR site, Isle of Wight. Scale bar in mm.


The next limestone (Fig. 19) is largely made up of mud-filledViviparus infracretacicus. Shortly above, the highest (Fig. 20) ischaracterized by dominantly concordant, locally stacked, nestedand imbricated Filosina and preserves overgrowths of fibrouscalcite on its upper and lower surfaces. Shaly mudstonesimmediately above yield aragonitic and pyritic Filosina, Modiolus

cf. aequalis, Viviparus infracretacicus, small globular gastropods(possibly neritids), ostracods (Cypridea spinigera) and fish debris.The highest 3 m of the formation comprise black shaly mudstonewith commonly pyritized Paraglauconia cf. fittoni Morter and small,thin-shelled oysters. Foraminifera (Ammobaculites obliquus, Textu-

laria pulchella, Ammodiscus cf. cretaceus) also occur. These beds areerosively overlain by the richly fossiliferous Perna Beds Member atthe base of the Lower Greensand Group.

Shell beds within the highest 20 m of the Shepherd’s ChineMember contain abundant reworked Upper Jurassic fossils(Radley, 1995; Radley et al., 1998c; Fig. 22). Calcitic elementsinclude bivalves (Nanogyra nana, Nanogyra virgula, Actinostreon

solitaria, Chlamys textoria), echinoid spines (Plegiocidaris flori-

gemma; Fig. 22), serpulids (Serpula sulcata) and foraminifera(predominantly Lenticulina muensteri). Phosphatized fragments ofammonites (Pavlovia sp.) also occur. A record of belemnites (Ruffelland Radley, cited by Harding and Allen, 1995) is also probablyfounded on derived Jurassic material.

A whole-rock sample of oysters, echinoid debris and ?Viviparus

from the upper part of the Shepherd’s Chine Member gave d13Ccompositions of �4.27% and d18O compositions of �5.09% (Allenand Keith, 1965). Subsequent sampling and analysis of isolatedoyster and Filosina shells yielded values of +1.16/�2.90% and�7.07/�5.32% respectively (Allen et al., 1973).

10.1.3. Interpretation

White (1921) estimated that this site preserves the highest25 m of the Wessex Formation. Sections cleared by storms in1992–1993 revealed over 50 m of distal alluvial strata (Radley,1994a; Figs. 14 and 15), closely comparable both lithologically andpalaeontologically to the beds seen at the Compton Bay–Brighstone Bay site. Oxidized mudstones represent pedogenicallyaltered alluvium, the varying intensities of colour-mottling,reddening and pseudoanticline development suggesting variableflood durations and subtle topographic variations (Wright et al.,2000). The abundant trackways reveal drier areas on thefloodplain, inhabited at least periodically by large numbers ofdinosaurs. Thinner sand bodies are interpreted as crevasse splaysand the fine-grained, laterally accreted unit in the lower part of thesuccession is seen as a point bar. Much of the soft sedimentdeformation in the latter is attributable to dinosaur trampling(Figs. 14 and 17), pointing to frequent fluctuations in river stage.Amongst the gastroliths, a Hercynian-overprinted late Precambri-an pebble indicates primary derivation from the Armorican massifand secondary recycling via Permian-Triassic pebble beds, proba-bly on the eastern flanks of the Cornubian massif (Allen, 1975;Fig. 9). The pebble of silicified wood (Araucarioxylon) was sourcedpossibly from Lower Purbeck Beds, although a Wealden sourcecannot be ruled out.

The conchostracan-rich mudstone near the base of thesuccession suggests the former presence of an ephemeral pond.Notwithstanding a superficial similarity to the lacustrine large-Viviparus limestones of the Upper Weald Clay (ConeyhurstCommon and Cranleigh sites in the Weald Sub-basin), the Viviparus

sandstone is probably a crevasse splay or channel fill.The thick organic-rich lignitic interval in the upper part of the

succession (Fig. 14) is seen as the fill of a long-standing floodplainpond or lake. The sediment represents a combination of verticallyaccreted ‘background’ material and flood debris, indicatingperiodically heavy rainfall. Amongst the allochthonous input,

the plants (some burnt) and dinosaur bones are elements of thefloodplain biota, while molluscs, fish, and aquatic reptiles probablyinhabited the water body itself. As at Brighstone Bay, etched shellsreflect acidic surface waters and intense weathering of the nearbysub-basin margin (Fig. 8) and/or Cornubian massif (Fig. 9).

The Vectis Formation marks lagoonal transgression, possibly inresponse to reduction of sediment supply and/or eustatic sea-levelrise. The succession compares closely with that at the ComptonBay–Brighstone Bay site, confirming establishment of an open,laterally homogeneous sedimentary regime across the Wessex

Fig. 23. Southern English (non-marine Lower Cretaceous) Wealden molluscs and

inferred salinity ranges.


Sub-basin (Fig. 13), prior to the main Aptian marine transgression.Pavements of freshwater-oligohaline Filosina gregaria, Viviparus

spp. and ostracods within the Cowleaze Chine Member indicate ashallow, subaqueous lagoonal environment disturbed by waveand/or current-induced winnowing. The mudcracked horizonsindicate periodic desiccation, the fossil content of the lowestsuggesting attendant mass mortality of fish populations.

Increasing sand content in the higher part of the CowleazeChine Member suggests progradation of a small sand body nowrepresented by the Barnes High Sandstone. Yoshida et al. (2001)suggested an origin as part of an estuarine tidal bar complex, butearlier fluvio-deltaic interpretations (Stewart, 1978a; Stewartet al., 1991) are probably more valid (see Compton Bay–BrighstoneBay site account). Coarser grained, wave-rippled and bioturbatedunits in the upper part of the Barnes High Sandstone indicateintermittent reworking in a shallow-water environment, thoughthey apparently lack the dinosaur tracks and abundant molluscspresent at Brighstone Bay.

The apparent absence of mudcracked surfaces in the Shepherd’sChine Member suggests a greater frequency and/or duration ofcoastal flooding as compared with Compton Bay–Brighstone Bay.Divisions A–F of Stewart et al. (1991; Fig. 12) are tentativelyidentified; the small-scale coarsening-upward cycles similarlyattributed to distal deltaic progradation and retreat. Many of themarker beds seen at Compton Bay–Brighstone Bay are detectable,notably several storm coquinas (Radley and Barker, 2000a) andbrackish-marine horizons within the highest strata (Figs. 10 and12). The characteristic bundle of quasi-marine faunal influx ! bio-bioclastic limestone ! Diplocraterion ironstone ! quasi-marinefaunal decline also documented at the Compton Bay–BrighstoneBay site is evident.

Harding and Allen’s (1995) study of dinocyst distributionconfirms the fluctuating but overall low salinities indicated by thelow-diversity, opportunistic Filosina-Viviparus dominated faunas(Figs. 11 and 23). Millimetre-scale reworking events evidenced byostracod shell beds (Ruffell, 1988; Harding and Allen, 1995)provide further evidence for weak storm activity in the Vectislagoon.

The reworked Jurassic fossils account for previous records ofindigenous marine biota in the Shepherd’s Chine Member. Many(e.g. Nanogyra nana, Chlamys textoria, echinoid spines; Fig. 22)came from Oxfordian–Kimmeridgian boundary beds. WornNanogyra virgula shells and phosphatized Pavlovia fragmentsindicate lower Kimmeridgian and upper Kimmeridgian–lowerPortlandian sources, respectively. The fragile calcitic nature ofmany reworked Jurassic elements suggests a proximal sourcealong the footwall of the Isle of Wight–Portsdown High (Fig. 7),now preserved as steeply dipping faults beneath the Isle of Wightmonocline. This is supported by Ruffell and Garden’s (1997)reported clay mineral values, which are suggestive of weatheringbedrock immediately to the north.

Radley et al. (1998c) proposed the present-day Fleet lagoon ofthe Dorset coast, south-west England, as a possible analogue of theVectis lagoon margin. There, late Oxfordian–lower Kimmeridgianbeds outcrop in low cliff and foreshore sections, separated from thebrackish-water Fleet by a muddy intertidal zone. Strengtheningthe analogy, fossils (including many of the taxa present at SandownBay) are washed from bedrock and mudflows and mixed withUpper Cretaceous flint and recent biogenic debris includingmollusc shells. Presumably these materials are periodicallywashed offshore and become incorporated into the modernlagoonal sediments.

Allen et al. (1973) questioned the validity of isotopic data earlierobtained from a whole rock sample of skeletal carbonate collectedfrom the upper part of the Shepherd’s Chine Member (Allen andKeith, 1965). Identification of Jurassic elements amongst the

materials (Radley et al., 1998c) confirms the invalidity of the wholerock approach.

The Vectis reverse polarity magnetozone was established byKerth and Hailwood (1988) at this site. Spanning the intervalwithin the Shepherd’s Chine Member between 13 m and 29 mabove the Barnes High Sandstone, this is tentatively correlatedwith the Lower Aptian reverse polarity Chron CM 0. Sedimento-logical and palaeontological evidence also strongly suggests thatthe highest part of the Vectis Formation is of early Aptian age (seeCompton Bay–Brighstone Bay site).

The site promises well for detailed correlation with upperWealden exposures on the south-west coast of the Isle of Wight,


and the uppermost Weald Clay of the Weald Sub-basin. Thesuccession of river floodplain sediments is easily accessible,displaying dinosaur trackways, soil horizons and seasonal flooddeposits containing well-preserved plant remains, reptile bonesand freshwater invertebrates. The higher beds clearly record theeventual flooding of these environments by shallow muddy lake-lagoonal environments, inhabited by ostracods, molluscs, fish andmany other organisms.

10.1.4. Conclusions

The section provides excellent opportunities for future work onlate Wealden palaeoenvironments and correlation. In particular,the plant debris beds of the Wessex Formation are importantrepositories of palaeontological data. Numerous sand bodieswithin both the Wessex and Vectis formations await detritalpetrographic studies, and prospects are good for clay mineralogicaland palynological analyses of both overbank and lagoonal

Fig. 24. Vertical section through the Wessex Formation (Barremian) north-west of Hanov

p. 34), incorporating new palaeontological data.

sediments. Widespread preservation of original shell aragoniteindicates that further investigations into carbon isotope ratioscould be rewarding. Similarly, Harding and R.M. Allen’s study offine-scale environmental fluctuations using dinocysts and ostra-cods could profitably be applied to other fossil groups.

10.2. Compton Bay–Brighstone Bay, Isle of Wight (SZ 369851–SZ

452792)


This site comprises nearly continuous cliff and foreshoreexposures of the upper part of the Wessex Formation and thewhole of the Vectis Formation, preserved on the northern limb ofthe Brighstone Anticline along 11 km of the south-west coast of theIsle of Wight between Compton Bay and Atherfield Point (Figs. 1, 6,7, 24–27). The sections are of key importance for investigating anddemonstrating the age, origin, depositional environments and

er Point, Isle of Wight (Compton Bay–Brighstone Bay GCR site). After Stewart (1978a,

Fig. 25. Vertical section through the Wessex Formation (Barremian), Brighstone Bay, Isle of Wight (Compton Bay–Brighstone Bay GCR site). After Stewart (1981a, fig. 3.7),

incorporating new palaeontological data.


palaeoecology of the Island’s Wealden, and relationships with sitesto the east (Sandown Bay) and west (Swanage Bay). Currentlithostratigraphic nomenclature (Fig. 6) was introduced by Daleyand Stewart (1979) who named the constituent members of theVectis Formation after topographic features along the south-eastern part of the section (Fig. 1).

Early accounts (e.g. Webster, 1816; Conybeare and Phillips,1822; Sedgwick, 1822; Fitton, 1824, 1836, 1847; Mantell, 1844a,1846, 1848a,b, 1854; Wilkins, 1859; Bristow, 1862; Judd, 1871;Reid and Strahan, 1889; Norman, 1887; White, 1921) outlined the

Wealden stratigraphy and palaeontology. Further stratigraphicaldetails have been provided by Colenutt and Hooley (1906), Stewart(1978a,b, 1981a), Ruffell (1988), Ruffell and Batten (1990), Stewartet al. (1991), Wach and Ruffell (1991), Radley (1994b), Radley andBarker (1998a), Wright et al. (2000) and Yoshida et al. (2001). Thegeology was summarized and photographically illustrated byRadley (2006).

Important palaeobotanical studies were carried out for exampleby Carruthers (1870), Alvin (1974), Hughes (1958, 1975, 1994),Oldham (1976), Harris (1981), Alvin and Muir (1970), Watson

Fig. 26. Vertical section through the Vectis Formation (Barremian up to early Aptian), Compton Bay, Isle of Wight (Compton Bay–Brighstone Bay GCR site). After Radley and

Barker (1998a, fig. 3).


(1977), Alvin et al. (1978, 1981, 1994), Francis (1987), Watson andSincock (1992), Nicholas et al. (1993), Feist et al. (1995), Watsonand Alvin (1996), Simpson (1999), Collinson et al. (2000), Watsonet al. (2001), Watson and Cusack (2005) and Bray and Anderson(2008). Grocke et al. (1999) and Robinson and Hesselbo (2004)documented the carbon-isotope composition of fossil woodfragments from the Vectis and Wessex formations.

Palynological research has been conducted for example byBatten (1982, 1996a,b,c), Hart et al. (1987), Batten and Lister(1988a,b), Harding (1988), Hughes et al. (1979), Hughes andMcDougall (1990a) and Hughes (1994). Ostracods were docu-mented by Sowerby (1836), Jones (1878, 1885, 1888, 1959),Anderson (1966, 1967, 1985), Kilenyi and Neale (1978), Hartet al. (1987), Keen (1988), Radley (1994b), Horne and Martens(1998) and Wilkinson (2002, 2008). Foraminifera have beendocumented by Radley (1994b, 1995) and molluscs for exampleby Mantell (1844b, 1847), Sowerby (1846), Meyer (1872),Jackson (1933), Casey (1955), Mongin (1961), Morter (1978),Cleevely and Morris (1988), Barker et al. (1997b) and Radley andBarker (1998b, 2000b). Insects were documented by Twitchett

(1995), Jarzembowski (1995, 1999) and Jarzembowski et al.(2008). Selden (2002) described a new genus and species ofspider. The internationally important vertebrate faunas weresummarized by Insole and Hutt (1994), Benton and Spencer(1995), Dineley and Metcalf (1999), Martill and Naish (2001),Sweetman and Martill (2010) and Sweetman and Insole (2010).Evans et al. (2004) recorded lizard and amphibian remains andFreeman (1975) made an important study of vertebratetaphonomy. The diagenetic histories of dinosaur bones weredocumented by Clarke (1991, 2004), Clarke and Barker (1993)and Barker et al. (1997a).

Invertebrate trace fossils were recorded and interpreted byStewart (1978a,b), Stewart et al. (1991), Wach and Ruffell (1991),Radley et al. (1998b), Radley and Barker (2000a), Goldring et al.(2005) and Francis and Harland (2006). Dinosaur tracks have beendocumented by Beckles (1851, 1852, 1862), Mantell (1854), Daleyand Stewart (1979), Delair (1983, 1989), Wach and Ruffell (1991),Radley (1994c, 1997a), Radley et al. (1998a) and summarized bySarjeant et al. (1998), Wright et al. (1998), Martill and Naish (2001)and Goldring et al. (2005).

Fig. 27. Vertical section through the Vectis Formation (Barremian up to early Aptian) between Barnes High and Atherfield Point, Isle of Wight (Compton Bay–Brighstone Bay

GCR site).


Webster (1816), Mantell (1848b), Meyer (1872) and Relf (1916)were amongst the first workers to consider the palaeoenviron-mental and palaeoecological significance of the succession. In thelate 1970s and early 1980s David Stewart established a palaeoen-vironmental framework (Stewart, 1978a,b, 1981a,b, 1983) foundedon detailed sedimentological study. The growing body ofsedimentological data includes work by Ruffell (1988), Allen(1989, 1998), Ruffell and Batten (1990), Stewart et al. (1991), Wachand Ruffell (1991), Radley et al. (1998a), Radley and Barker (1998b,

2000a,b), Wright et al. (2000), Webb (2001), Yoshida et al. (2001),Jackson et al. (2003) and Sweetman and Insole (2010). Robinsonet al. (2002) studied the stable-isotope geochemistry of calcretenodules. The palaeogeology of nearby intrabasinal highs has beeninvestigated through studies of reworked fossils by Radley (1993a,2005), Radley and Barker (1998a) and Martill and Barker (2000).Additional data on clay mineral distributions were given by Ruffelland Garden (1997), Ruffell and Worden (2000), Wright et al.(2000), Jeans et al. (2001) and Jeans (2006). Ruffell and Worden’s


account also includes spectral gamma-ray data from the VectisFormation. The palaeoclimatic significance of the Wessex Forma-tion was briefly reviewed by Haywood et al. (2004).

Chronostratigraphic interpretations have involved biostratig-raphy (Anderson, 1967, 1985; Hughes and McDougall, 1990a;Feist et al., 1995), event stratigraphy (Hughes and McDougall,1990a,b; Allen and Wimbledon, 1991), magnetostratigraphy(Steel, 1986; Kerth and Hailwood, 1988), sequence stratigraphy(Wach and Ruffell, 1991) and fossil wood carbon-isotopestratigraphy (Robinson and Hesselbo, 2004). The site has longbeen a popular destination for geological field excursions (Holmesand Leighton, 1892; Colenutt and Hooley, 1906, 1919; Herries,1910; Relf, 1916; Hall, 1933; Barnard, 1948; Waite, 1964, 1965;Stinton, 1971; Daley and Stewart, 1979; Radley, 1994c) andcontinues to attract much attention (Insole et al., 1998; Martilland Naish, 2001).

10.2.2. Description

The Wessex Formation (formerly ‘Wealden Marls’) is dominat-ed by oxidized, varicoloured and predominantly red mudstoneswith rootlet traces, goethite, haematite, and calcrete nodules,slickensides, pseudoanticlines, vertical mottling and layers ofmud-chip breccia. These units are interspersed amongst sand-stones and intraformational conglomerates, and grey coloured,lenticular, poorly sorted, crudely upward-fining pyritic andsideritic admixtures of mudstone, silt, siltstone, calcrete andironstone clasts, lignitic wood, bones and shells (‘plant debris beds’of Oldham, 1976).

The overlying Vectis Formation (formerly ‘Wealden Shales’) isdominated by grey, shelly, shaly mudstones (some fossiliferous),bioturbated silty mudstones and thin sandstones (Cowleaze Chineand Shepherd’s Chine Members), with a thicker interveningarenaceous interval; the Barnes High Sandstone Member(Fig. 6). Younging sections of both formations occur to thenorth-west and south-east of Hanover Point (SZ 379837; Figs. 1and 24–27). These differ in detail as follows.

10.2.2.1. Hanover Point to Small Chine Fault (SZ 379837–SZ

374845).

10.2.2.1.1. Wessex Formation. The younging succession of theWessex Formation (base not seen) is traceable north-west fromHanover Point (Figs. 1 and 24). Stewart (1978a) recorded about150 m of strata; Robinson and Hesselbo (2004) measured athickness of 125 m. Much of the overlying Vectis Formation ispreserved, the highest part truncated by a fault at SZ 374845(‘Small Chine Fault’ of Wach and Ruffell, 1991; Fig. 28). North-westof the fault, the uppermost beds of the Wessex Formation are

Fig. 28. Cross section of cliff exposures between Compton Bay and Shippards Chine, Isle

After Radley and Barker (1998a, fig. 2).

repeated and overlain by a thin development of the VectisFormation (White, 1921; Radley and Barker, 1998a; Fig. 28).

At Hanover Point the lowest part of the Wessex Formationincludes the Hanover Point Sandstone (Fig. 24). Loosely known asthe ‘Pine Raft’, this unit and associated mudstones contain partlycalcitized conifer trunks (up to 1 m in diameter and 2–3 m long;some with annual growth rings), fragments of branches andpyrogenic fusain (fossil charcoal), together with spores and amberfragments (Fig. 29). Haworth et al. (2005) studied stomatalcharacters of conifer (Pseudofrenelopsis parceramosa) cuticle fromthis level. Collinson et al. (2000) additionally recorded a beetleelytron and probable termite coprolites from this unit (also seeFrancis and Harland, 2006). The detrital petrography of the sandfraction is dominated by Cornubian elements (e.g. u-feldspar 7%dropping to <0.1% in fine laminae; tourmaline up to 54% of theheavy grains (32% fine aggregates in total tourmaline); traces oftopaz).

Associated mudstones have one of the highest percentages ofdetrital kaolinite known in the Wealden (62%). Overlyingmudstones and thin sands yielded well preserved unionoidbivalves (Margaritifera (Pseudunio) valdensis; Fig. 11, includingMantell’s (1844b, 1847) syntypes and Mongin’s (1961) lectotype),terrestrial and aquatic vertebrates, and several levels of Iguanodon

tracks. The overlying mudstone-dominated succession contains ahard sandstone bed (0.4–0.75 m thick), preserving large Iguanodon

footcasts (up to 0.7 m in length) on its underside (Radley, 1994c).This bed also encloses Beaconites burrows and scattered gastro-pods (Viviparus fluviorum). Wright et al. (2000) recorded pseu-doanticlines, vertical mottling and goethite nodules from red tocolour mottled mudstones within this part of the succession.

Plant debris beds higher up (Fig. 24) contain mineralized andfusainized plant macrofossils including branches, foliage and conesof the forest tree Pseudofrenelopsis parceramosa (Hughes, 1975;Alvin et al., 1978, 1981; Robinson and Hesselbo, 2004), as well asepiphyllous fungi (Alvin and Muir, 1970) and abundant palyno-morphs (Hart et al., 1987; Harding, 1988). The Pseudofrenelopsis

wood exhibits uneven growth rings (Allen, 1998). Unionoidbivalves also occur (Radley and Barker, 2000b), includingSubnippononaia fordi (S. Sweetman, personal communication).The plant remains and those of the Pine Raft make up Hughes’Brook flora (Reid and Strahan, 1889; White, 1921; Hughes, 1958,1975; Oldham, 1976; Francis, 1987). Silicified beach-wornfragments of Cycadeoidea (Carruthers, 1870; Watson and Sincock,1992) and Tempskya are common along this coast, sourced possiblyfrom a number of Early Cretaceous formations including theWessex (Radley, 1997a; Watson and Lydon, 2004). Carbon-isotopeanalyses of fossil wood fragments sampled throughout the

of Wight (vertical scale much exaggerated). Compton Bay–Brighstone Bay GCR site.

Fig. 29. The ‘Pine Raft’ at the base of the exposed Wessex Formation succession on the foreshore below Hanover Point, Isle of Wight (Compton Bay–Brighstone Bay GCR site). A

calcified conifer trunk can be seen in the foreground, approximately 6 m in length, partly obscured by seaweed. The cliffs behind expose varicoloured mudstones and thin

sandstones. Photo taken 1921.

(Reproduced by the permission of the British Geological Survey.� NERC. All rights reserved. IPR/139-19CT).


succession have an average value of �22.7% (Robinson andHesselbo, 2004).

Fining-upward sandstone units in this part of the sectioninclude an erosively based, laterally accreted sand body (c. 3 mthick) described by Stewart (1983). North-west of Shippards Chine(SZ 376842), the upper part of the trough cross-bedded ComptonGrange Sandstone (c. 2 m thick; Fig. 24) contains abundant largepink quartz grains. Towards the top of the Wessex Formation,further sandstones (some lenticular) are penetrated by Beaconites

burrows. An example just below the top of the formation displaysyellow vertical striping and fines up into grey and yellowmudstone (c. 0.4 m) with small limonitic nodules.10.2.2.1.2. Vectis Formation. The Cowleaze Chine Member com-prises grey mudstones, clay-ironstones and bioturbated sands (c.10 m thick). Ostracods (Theriosynoecum fittoni; Hart et al., 1987),bivalves (Filosina gregaria) and gastropods (Viviparus infracretaci-

cus) occur in the mudstones. An ex situ siltstone block, probablyfrom this member, has yielded a small planorbiform gastropod(Radley, 1994c). Hart et al. (1987) recorded a diverse miosporeassemblage dominated by bisaccate pollen, with rarer dinocysts(Australisphaera sp.), fungal remains and algae including Celyphus

rallus.The Barnes High Sandstone (c. 11 m thick) comprises several beds

of medium to coarse-grained sandstone interbedded with mudstone.The sandstones are poorly to moderately sorted and exhibit lateralaccretion surfaces (Stewart, 1978a, 1981a), trough cross-bedding,current ripples and rare bidirectional ripples, flaser beddingand lenticular bedding. Current directions are predominantlysouth–south–east and subordinately west–north–west/south–west

(Yoshida et al., 2001). At least one of the sandstones containsbivalve moulds; wood fragments also occur. The intercalatedmudstones are weakly laminated and enclose sandstone lenticles(Yoshida et al., 2001). Near the base of the member, a tabularclay-ironstone bed yields well-preserved ostracods, Filosina andViviparus. Finally, the Shepherd’s Chine Member (c. 45 m preserved)is dominated by grey mudstones and silts including insect-bearing fine sandstone gutter casts (Radley, 1994c; Twitchett,1995), grey ostracodal shales and layers of Filosina-limestone (White,1921). One or more of the latter includes fish debris and preservessmall hypichnial Diplocraterion, endichnial Planolites and possibleLockeia.

10.2.2.2. Small Chine Fault–Compton Bay (SZ 374845–369851).

10.2.2.2.1. Wessex Formation. Approximately the highest 58 m ofthe Wessex Formation are repeated beyond the fault (White, 1921;Fig. 28) and are mainly varicoloured to dominantly red mudstones.Some display vertical mottling and/or enclose small ironstonenodules and rootlet traces, thin intraformational conglomerates,sandstones (some carbonaceous) and plant debris beds. Softsediment deformation occurs throughout.10.2.2.2.2. Vectis Formation. The overlying Vectis Formation isapproximately 33–34 m thick here (Radley and Barker, 1998a;Figs. 10, 12, 27 and 28). The lowest unit of the Cowleaze ChineMember (4 m thick) is a pale sand (0.6 m thick; Fig. 26). Theoverlying shelly, pyritic and bioturbated grey mudstones and clay-ironstones contain Filosina gregaria, Viviparus infracretacicus

(Fig. 30), ostracods (Theriosynoecum fittoni), fish debris, insectremains (a blattodean forewing) and plant fragments.


The succeeding Barnes High Sandstone Member (5 m thick;Fig. 26) comprises alternating poorly cemented coarse-grainedferruginous sandstones, muddy sandstones and bioturbatedsandy mudstones. The Shepherd’s Chine Member (25 m thick;Fig. 26) is dominated by shaly to sandy and bioturbated greymudstones, intercalated with fine sandstones, clay-ironstonesand laterally persistent sharp-based, ferroan calcite-cemented,sandy, slightly glauconitic bioclastic limestones (Figs. 10, 12 and31). These are principally made up of Filosina gregaria withsubordinate Viviparus infracretacicus. The bivalve shells areconcordant to variably oriented and locally stacked, nested orimbricated.

Fig. 30. Stratigraphic distribution of shelly fossils within the Vectis Formation

(Barremian up to early Aptian) of Compton Bay, Isle of Wight (Compton Bay–

Brighstone Bay GCR site). After Radley and Barker (1998a, fig. 4),

reproduced by permission of Elsevier.

Fining-upward cycles (up to c. 1 m thick) occur at some levels ofthe Shepherd’s Chine Member, grading from lenticular troughcross-laminated fine sandstones and fine sandstone gutter fills upinto grey mudstones and shales. Filosina gregaria, Viviparus

infracretacicus, ostracods (Theriosynoecum fittoni, Mantelliana

mantelli and Cypridea spp.) and fish debris occurs in shaly bedsapproximately 6.5 m above the base of the member (Fig. 30) andreappear at intervals almost to the top. Limestones are bestdeveloped 16 and 1.4 m below the top of the formation. Additionalto Filosina and Viviparus, the lower limestone has yielded a worn,derived Callovian or Oxfordian (Middle-Upper Jurassic) oyster(Gryphaea (Bilobissa) sp.) and its base preserves casts of shallowpolygonal mudcracks and small Diplocraterion burrows. Partingswithin the limestone display ?Planolites and smaller, thread-likeburrows. M.J. Barker (personal communication) has also notedsmall pod-like hypichnia, possibly Lockeia. The top is vaguelyinterference-rippled. The higher limestone yields abundantFilosina and scattered oyster fragments and its base preservesmudcrack casts (Fig. 31).

Oysters (Praeexogyra cf. distorta), corbulids (Cuneocorbula cf.arkelli), ostracods (including Paranotacythere inversa), agglutinatedforaminifera (Ammobaculites obliquus and Textularia pulchella) andpyritized sponge spicules occur in shaly mudstones between 6 and7 m below the top of the formation (Figs. 26 and 30). This intervalalso includes a thin clay-ironstone band penetrated by Diplocra-

terion burrows (Fig. 12). The highest 0.9 m of the member, belowerosively based Perna Beds (Lower Greensand Group), are blackmudstones with cassiopid gastropods (Paraglauconia fittoni;Fig. 12) and thin-shelled bivalves including Cuneocorbula.

Anderson (1967) listed ostracods from the ‘Wealden Shales’near Compton Chine (SZ 368852), probably referring to thissection. In addition to the species noted above he recordedCypridea rotundata, Cypridea tenuis, Cypridea valdensis and Cypridea

warlinghamensis. Ruffell and Garden (1997) recorded kaoliniteabundances of around 30% from mudstones at unspecified levelswithin the Vectis Formation.

10.2.2.3. Brook Bay–Atherfield Point (SZ 380837–SZ 452792). Ap-proximately the highest 180 m of the Wessex Formation and theoverlying Vectis Formation (c. 55 m) are exposed in sectionsrunning for 9 km south-eastwards from Hanover Point toAtherfield Point (Figs. 1, 25, 27, 32–34). The type section of theVectis Formation lies south-east of Barnes High (SZ 438806–452792; Stewart et al., 1991).10.2.2.3.1. Wessex Formation. South-east of Hanover Point, BrookBay and Roughland Cliff (SZ 380837–SZ 390829) expose varico-loured mudstones with rootlet traces, layers of reworked ironstonenodules, at least one calcrete horizon, thin sandstones and plantdebris beds. S. Sweetman (personal communication) has collecteda previously unrecorded high spired gastropod from a plant debrisbed south-east of Roughland Cliff. The cross-laminated BrookSandstone (Stewart, 1978a; up to 3 m thick), may be the source ofIguanodon and sauropod or ankylosaur footcasts found on theadjacent foreshore (Radley, 1994c).

Underneath the Sudmoor Point Sandstone lie up to 6 m ofvaricoloured and red mudstones; the oldest beds seen south-eastof Hanover Point. These contain concentrations of Margaritifera

(Pseudunio) valdensis in apparent life position and poorly sortedlenticular muddy intraformational conglomerates with a fairlydiverse unionoid fauna (Stewart, 1978a; Allen, 1998; Radley andBarker, 2000b). Vertebrate fossils include turtle and dinosaurremains, small meniscate burrows also occur. Robinson et al.(2002) recorded calcrete nodules 3 m below the Sudmoor PointSandstone south of Brook Bay (SZ 390828). These have anaverage d13C content of �10.1 to �10.4% and d18O of �3.9to �4.1%.

Fig. 31. Ex situ blocks of limestone derived from the Shepherd’s Chine Member (upper Vectis Formation), Compton Bay, Isle of Wight. (Compton Bay–Brighstone Bay GCR site).

Note casts of desiccation cracks and pavements of small bivalve shells (Filosina) preserved on several blocks. Photograph taken 1902.

(Reproduced by permission of the British Geological Survey. � NERC. All rights reserved. IPR/139-19CT).

Fig. 32. View from Sudmoor Point looking south-eastwards; Brighstone Bay, Isle of Wight (Compton Bay–Brighstone Bay GCR site). Cliff sections within the Wessex Formation

(Barremian) expose the Sudmoor Point Sandstone with mudstone-dominated strata above and below. In the distance, the high ground of St Catherine’s Down is capped by the

Upper Cretaceous Upper Greensand Formation and Chalk Group. Photograph courtesy of Trevor Price, Dinosaur Isle.


Fig. 33. Cliff sections in the Vectis Formation (Barremian up to early Aptian) near Cowleaze Chine, Isle of Wight (Compton Bay–Brighstone Bay GCR site). Pale band at cliff base

is the ‘White rock’ sandstone at the base of the Vectis Formation. Above, darker argillaceous beds of the Cowleaze Chine Member (c. 6.5 m thick) are overlain by the

conspicuous Barnes High Sandstone Member (c. 6 m). At the top of the cliff the lowest part of the argillaceous Shepherd’s Chine Member is dominated by fining-upward cycles

of fine sandstones, siltstones and mudstones. Photograph courtesy of Trevor Price, Dinosaur Isle.


North-west of Sudmoor Point (SZ 389830), varicolouredmudstones are overlain by a well-sorted, dominantly fine grainedsandstone reaching 7 m in thickness (Sudmoor Point Sandstone;Figs. 32 and 35). This is traceable for 1.8 km south-eastwards andcomprises several erosively based, fining-upward laterally accret-ed units separated by erosion surfaces. The bases of the unitslocally consist of intraformational conglomerate comprising clastsof sandstone, siltstone, calcrete, mudstone and reptilian bone. Thelower parts of the units display trough and planar cross-bedding,small-scale cross-lamination, climbing ripple lamination, softsediment deformation and intraclastic seams. These typically fineup into alternating mudstones and climbing ripple-laminated orbioturbated sandstones (Stewart, 1981b). Loose blocks of theSudmoor Point Sandstone have revealed mudcracked partings,intervals riddled by Beaconites burrows (Goldring et al., 2005) and apavement of armoured mudclasts comprising subrounded torounded red silty mudstone (diameter up to 65 mm) impregnatedwith subrounded to subangular sandstone chips and sporadicquartz pebbles. The base and top of the sandstone locally preservesIguanodon trackways (Delair, 1983 and D.M. Martill, personalcommunication).

At Chilton Chine (SZ 408822; Fig. 1), red to green mudstones(seen to 2 m) immediately above the Sudmoor Point Sandstoneenclose layers of small calcrete nodules (Fig. 25). These yieldedvalues of �10.3 to �14.2% for d13C and �4.3 to �6.3% for d18O.

Supervening plant debris beds comprise poorly sorted, lenticular,pyritic and sideritic admixtures of mud, silt and sand, ironstoneand calcrete clasts, wood (sometimes fusainized), unionoid bivalveshells and dinosaur teeth and bones. These are traceable forapproximately 1.75 km to the north-west (Stewart, 1978a; Radleyand Barker, 2000b). Recognizable plant material includes coniferremains (Brachyphyllum; I.C. Harding, personal communication).Carbon-isotope values of wood fragments from throughout thesection have an average value of �22.7%, and demonstrate a broadup-section trend towards more positive values (Robinson andHesselbo, 2004). The bivalves are Margaritifera (Pseudunio)valdensis, Subnippononaia fordi (including a paratype; Barkeret al., 1997b) and other taxa possibly new to science (Radleyand Barker, 1998b, 2000b; Fig. 11). The shells are often fullyarticulated, neomorphically replaced by calcite and mineralizedinternally. Ligaments, umbonal dissolution scars and internal shellstructure are preserved. M.J. Barker (personal communication) hasidentified decalcified gastropod eggs on an internal mould ofMargaritifera (Pseudunio) valdensis. Calcified examples of the eggshave been noted encrusting dinosaur bones from other plant debrisbeds within the succession (Martill and Naish, 2001).

The remainder of the Wessex succession can be traced in cliffand foreshore sections towards Cowleaze Chine (SZ 444801;Fig. 25). Again it is dominated by varicoloured and haematitic redmudstones comprising illite, illite–smectite and kaolinite, with

Fig. 34. Cliff sections in the Shepherd’s Chine Member (upper Vectis Formation) at Shepherd’s Chine, Isle of Wight (Compton Bay–Brighstone Bay GCR site). Note small-scale

fining-upward cyclicity ranging from pale fine-grained siltstones and sandstones up into darker mudstones. Photograph courtesy of Trevor Price, Dinosaur Isle.


palygorskite recorded from the highest beds (Ruffell and Batten,1990; Jeans, 2006). Vertical mottling is common, together withfurther developments of calcrete (d13C values of �9.1 to �15.2%;d18O values of �2.8 to �6.3%; Robinson et al., 2002), pseudoanti-clines and other signs of synsedimentary deformation. The raredinosaur remains in the oxidized mudstones are generally poorlymineralized and pale-coloured (Martill and Naish, 2001; J.D.Radley, personal observations). The mudstones are interspersedwith tabular to lenticular sandstones (some preserving Beaconites

and/or dinosaur tracks), intraformational conglomerates (somewith shells or reworked calcrete nodules) and plant debris beds.Current directions indicated by the Wessex sand bodies arepredominantly north-west/south-east (Stewart, 1978a). Prelimi-nary sampling reveals predominantly Cornubian detritus through-out, accompanied by varying traces of Armorican waste.

The upper parts of some plant debris beds display verticallyelongated, centimetre-wide patches of brown goethite (Wrightet al., 2000). Shortly above the Sudmoor Point Sandstone, twoclosely spaced plant debris beds have yielded probable gastrolithsand conifer amber which has revealed insects and a spider(Nicholas et al., 1993; Jarzembowski, 1995, 1999; Simpson, 1999;Selden, 2002; Jarzembowski et al., 2008). Bray and Anderson(2008) conducted pyrolysis–gas chromatography–mass spectrom-etry on amber samples which suggests that they are attributable topinacean or cheirolepidacean conifers. Most of the plant debrisbeds have yielded dinosaur and other vertebrate remains (Reid andStrahan, 1889; White, 1921; Benton and Spencer, 1995; Martill and

Naish, 2001). The bones tend to be well mineralized and dark-coloured. Rich microvertebrate assemblages occur, includingbones of amphibians and lizards, pterosaurs, rare mammal teethand possible bird teeth (Evans et al., 2004; Sweetman, 2008;Sweetman and Martill, 2010; Sweetman and Insole, 2010; S.Sweetman, personal communication). Francis and Harland (2006)described pellet-filled termite borings within fossil wood collectedfrom a plant debris bed occurring approximately 17 m below theGrange Chine Black Band (see below).

Palynomorph recovery is generally low from the oxidizedsediments. The plant debris beds and finer-grained channel fillsyield spores, pollen, algae and putative freshwater dinocysts (Alvinet al., 1978; Stewart, 1978a; Batten, 1982, 1996b,c; Batten andLister, 1988b). Etched calcareous nannofossils (Watznaueria

barnesae) are also recorded (Hart et al., 1987; Radley, 2005).Upward-fining, erosively based, laterally accreted bodies of

interbedded mudstone, mudclast conglomerate, siltstone and finesandstone (up to about 4.5 m thick) occur for example south-eastof Grange Chine (SZ 423815), roughly 100 m below the top of theformation (Stewart, 1983). The Grange Chine unit has yielded acemented mudstone cobble containing Sinemurian (Lower Juras-sic) ammonites (Promicroceras; Radley, 1993a). Preliminary gaschromatography analysis suggests that this rock might alsocontain oil (Wimbledon et al., 1996). The overlying plant debrisbed (Grange Chine Black Band, c. 1 m thick) provides a convenientmarker bed (Fig. 25) and has yielded well preserved gymnospermleaf fragments (Watson et al., 2001) and numerous vertebrate

Fig. 35. The Sudmoor Point Sandstone (Wessex Formation) meander belt between Roughland Cliff and Chilton Chine, Isle of Wight (Compton Bay–Brighstone Bay GCR site).

(a) Typical vertical sections through five of the sand bodies. (b) Reconstruction of the meander belt. Lower diagram shows directions of sediment accretion and current flow.

Adapted from Stewart (1981b, figs. 9 and 14).



remains. Voids in an Iguanodon rib from this bed contain siderite,kutnohorite, barite, pyrite and calcite (Clarke and Barker, 1993;Barker et al., 1997a; Clarke, 2004). Haworth et al. (2005)documented stomatal characters of conifer (Pseudofrenelopsis)cuticle from Grange Chine.

The highest 15 m of the Wessex Formation are dominated byoxidized mudstones. Dinosaur, crocodile and fish remains,gastroliths, unionoid bivalves, rare Beaconites burrows andpseudoanticlines characterize a red-coloured, slickensided, finelyintraclastic unit approximately 10 m from the top (Radley, 1994c;Radley and Barker, 2000b; Fig. 25). I.C. Harding (personalcommunication) has recorded reworked dinocysts, probably ofUpper Jurassic age, from this bed. These are distinguished from theco-occurring contemporaneous palynomorphs by their greaterthermal maturity. Acritarchs and miospores occur generally in theupper Wessex beds (Batten, 1982). Interbedded red slickensidedmudstones and lenticular sandstones in the highest 3 m (‘Beaco-

nites Beds’ of Radley and Barker, 2000b; Fig. 25) contain rootlets,reworked and in situ calcretes, dewatering structures, mudcracks,Beaconites, probable sauropod tracks, charophytes, fish remains,isolated dinosaur bones and nearly complete dinosaur skeletons(Hypsilophodon foxii). A reptilian gastrolith from these beds wasidentified as a phosphatic fragment of the late Oxfordian (UpperJurassic) ammonite Ringsteadia (Martill and Barker, 2000). Theuppermost sandstones are fine to medium-grained and poorly tomoderately sorted. Their bases are erosional and their uppersurfaces are either rippled or grade upward into mudstone.Internal cross-lamination is orientated commonly towards west-north-west and more rarely towards east-north-east. Ripple crestsare straight to slightly sinuous and symmetrical, with wavelengthsof 20–30 mm, and strike mainly north-east/south-west or north-west/south-east. Wave-current ripples (wavelengths 60–80 mm)also occur and steep-sided sandstone-filled channels (0.3–0.4 mdeep) trend south-west/north-east (Stewart, 1978b).10.2.2.3.2. Vectis Formation. As elsewhere, the Vectis Formation (c.55 m thick; Fig. 27) marks a distinct change from varicoloured togrey mudstones. Fossil wood carbon-isotope data from throughoutthe formation has supplied values in the range of approximately�27 to �18%, culminating in a sharp negative excursion at thebase of the overlying Lower Greensand Group (Grocke et al., 1999;Robinson and Hesselbo, 2004). The Cowleaze Chine Member is6.5 m thick (Fig. 27). The basal bed comprises coarsening-upwardfine to medium-grained pale grey sandstone (1 m thick) with plantdebris, remains of terrestrial and aquatic vertebrates, ostracods(Theriosynoecum fittoni) and bivalves (Filosina gregaria). This is Reidand Strahan’s (1889) ‘White rock’ (Figs. 27 and 33). The base islocally an erosion surface, load-casted in places and overlain by athin lag of quartz grains, wood fragments, fish and shell debris. Thehighest part consists of an erosively based sandstone; its toppenetrated by thin rootlets (up to 0.5 m in length) and Beaconites

burrows (Goldring et al., 2005). 200 m west of Cowleaze Chine thelower part of the White rock encloses abundant fusain and sandyintraformational conglomeratic lenses containing calcrete andironstone pebbles, fusain, bone fragments, Filosina and unionoids.There are also lenses of dark mudstone with ostracods and acid-etched? Filosina (Stewart, 1978a; Radley et al., 1998a) and fernremains (Onychiopsis; I.C. Harding, personal communication).These lithofacies also preserve large Iguanodon tracks. Yoshidaet al. (2001) also recorded current ripples, climbing ripples, andrare hummocky cross-bedding. Cornubian detritals occur in therootlet sand (u-feldspar 8%, tourmaline 11%, fine aggregates intotal tourmaline 5%). Webb (2001) recorded a detrital suitedominated by strained quartz grains (65.6%) and cemented byferroan calcite.

The remainder of the Cowleaze Chine Member is dominated bygrey mudstone with thin sandstones and clay-ironstones (Figs. 27

and 33). The upper part of the member exhibits upward-finingunits (Stewart, 1981a) similar to those described below from theShepherd’s Chine Member. Pavements of Filosina gregaria occurnear the base and Viviparus infracretacicus, Viviparus fluviorum,Filosina, unionoids, ostracods and charophytes are found in alenticular clay-ironstone bed near the top of the succession.Yoshida et al. (2001) noted sand-filled vertical cracks within themudstones immediately below the ironstone.

Feist et al. (1995) recorded the charophytes Atopochara

triquetra, Clypeator combei and Peckisphaera verticillata at variouslevels in the Cowleaze Chine Member. Palynological samples yieldabundant chlorococcalean algae and dinocysts, includingreworked marine Jurassic taxa (Batten and Lister, 1988b) andangiospermoid pollen (Hughes et al., 1979). The sand and clayfractions show marked differences from the preceding strata. Thuswhereas feldspar is unchanged at 8%, tourmaline is down to 11%and its fine-grained aggregates to 5%.

The succeeding Barnes High Sandstone Member (6 m thick;Fig. 27) rests on an abrupt, locally erosional surface (Stewart,1978a; Yoshida et al., 2001). It coarsens up from lenticular, wavy-bedded, slightly bioturbated muds, silts and fine-grained sands toflaser-bedded, trough cross-bedded and bimodally cross-bedded,fine to medium-grained, moderately to well sorted sandstones(Stewart, 1978a). Cornubian detritals recover somewhat after theWhite rock slump (e.g. tourmaline now 24% in the heavy suite).This fluctuation seems likely to have resulted from increasedsupply rather than destruction of unstable grains because feldsparremains at 8% of the total rock. Over the same interval Armoricanelements also increase (staurolite to 0.7%, kyanite 0.4%, garnet0.5%).

The wavy bedded lithologies of the Barnes High Sandstonereveal predominantly sand filled channels up to 10 m wide and0.6 m deep. Rare mudstone-dominated channels are up to 0.35 min depth and preserve small-scale fining-upward cycles. Oscillationripples, wave ripples, current ripples, ladder ripples, straight,sinuous and linguoid crested ripples and flat-topped ripples alloccur within the wavy bedded lithofacies. Ripple profiles rangefrom symmetrical to strongly asymmetrical, the latter with crestlines commonly oriented north-north-east/south-south-west.Undersides of sandstones overlying rippled surfaces commonlypreserve casts of brush marks, prod marks, grooves, scours, pitsand burrows. The bed surfaces themselves are locally draped withplant debris (some fusainised), including fragmented twigs, stemsand Weichselia pinnules (Stewart, 1978a).

The higher, cross-bedded sandstones exhibit discontinuouswavy flaser bedding, megaripples, large-scale trough and planarcross-beds and mudclasts (lining bases of cross-beds or resting onforesets). Cross-beds dip predominantly towards north-west andthe major lateral accretion surfaces towards north-west and north-east. Bimodal current indicators record flow from north-west andsouth-east (Yoshida et al., 2001). Filosina sp., ‘Unio’ cf. elongata,Viviparus infracretacicus, Viviparus fluviorum, fish debris, Iguanodon

and theropod dinosaur tracks and invertebrate traces (Planolites,Lockeia, Beaconites) occur in the highest 2 m (Stewart, 1981a;Stewart et al., 1991; Radley et al., 1998a,b; Goldring et al., 2005)which are locally calcite cemented. Some of the bivalve shellsdisplay umbonal etching. The highest sandstones preservemegaripples (indicating dominantly north-west flow) and smallersymmetrical ripples (Stewart, 1978a; Yoshida et al., 2001; Fig. 36).This member yielded the holotype of the dinocyst Vectensia varians

and the chlorococcalean alga Scenedesmus bifidus (Batten andLister, 1988b). Stewart (1978a) recorded an intraformationalconglomerate at the top of the member, comprising mudclastsand shells.

The Shepherd’s Chine Member (c. 43 m thick; Fig. 27)is dominated by shaly to sandy grey mudstones; thin, lenticular,

Fig. 36. Rippled surface of calcareous sandstone within the upper part of the Barnes High Sandstone Member (Vectis Formation), foreshore near Shepherd’s Chine, Isle of

Wight (Compton Bay–Brighstone Bay GCR site).


fine-grained, cross-laminated and bioturbated sandstones; nodu-lar clay-ironstones and several sharp-based bioclastic limestones.Mudstone samples yield illite (36–41%), illite-smectite (35–53%),kaolinite (20–24%) and traces of possible chlorite (Allen, 1998). Nokaolinite has been found at three horizons in the top 17.8 m wherepalygorskite appears (A.H. Ruffell, personal communication).

Fining-upward cycles (normally 0.6–0.9 m thick) occurthroughout the Shepherd’s Chine Member (Stewart et al., 1991;Figs. 34 and 37). As at Compton Bay these commence with anerosion surface overlain by mudstones with fine sandstone scourfills and shallow to steep-sided gutter casts. These pass up intobioturbated lenticular-bedded sands, silts and mudstones andultimately, laminated, occasionally fossiliferous mudstones andthin silts. Gutters, elongate plant fragments and shells aregenerally oriented north-east/south-west. Shelly laminae arecharacterized by broken to well-preserved shells; ostracods andbivalves showing 1:1 ratios of left and right valves (Stewart et al.,1991).

The gutter casts and scour fills are internally laminated andbioturbated, sometimes demonstrating several phases of erosionand deposition. Groove casts are sometimes present on their bases.Rare cross-lamination within the fills records north-easterlycurrent flow (Stewart et al., 1991). Recognizable burrows includeCochlichnus anguineus, Palaeophycus ispp., Planolites montanus,Unisulcus minutus and small pits, possibly generated by ostracods(Goldring et al., 2005). Basal lags of fish debris and shell fragmentsoccur, and the higher, finer-grained parts of the fills enclose plantdebris (including fusainized Weichselia), insects (including beetleand fly remains; Radley, 1994c; Twitchett, 1995) and near-complete skeletons of small fish. Heads (2006) additionallyrecorded a caddisfly larval case.

The Shepherd’s Chine Member furnished holotypes of theostracods Sternbergella cornigera, Mantelliana mantelli, Cypridea

pseudomarina, Cypridea caudata, Cypridea fasciata, Cypridea comp-

tonensis, Cypridea vectae, Cypridea insulae, Cypridea warlinghamen-

sis and Wolburgia atherfieldensis; also lectotypes of Sternbergella

cornigera and Mantelliana mantelli (Anderson, 1967, 1985).Palynological samples reveal miospores (Hart et al., 1987),dinocysts (some reworked), algae and fungal remains.

Stewart et al. (1991) subdivided the member into six majorunits based on vertical changes in sedimentary cyclicity andfossil content (Fig. 12). Divisions A and B, equating with the lowerpart of the member, are characterized by plant debris and lack ofshelly fossils; divisions C and D by well-developed fining-upwardcycles (as described above), shell pavements and ‘coquinas’ (thinshelly limestones), and division E is marked by poorer develop-ment of cycles and the appearance of ‘brackish-marine’ fauna.Division F marks a return to well-developed sedimentarycyclicity.

Strata broadly equating with divisions A and B (c. 13 m thick)comprise shaly to sandy mudstones (some bioturbated) andferruginous sandstones (some cross-laminated). Nodular clay-ironstone is well-developed in the upper part. Concentrations offusainized, fragmented ferns (Weichselia reticulata and rarerPhlebopteris dunkeri) occur within finely laminated sandstones(Harris, 1981; Radley, 1994c), herein termed the Weichselia bed(Fig. 27). Collinson et al. (2000) additionally recorded uncharredplant debris including cycad and bennettite cuticles from theplant-rich sandstones, together with beetle elytra, other arthropodcuticle fragments, and fish debris. The ostracods Theriosynoecum

fittoni and Cypridea spinigera appear in grey mudstones c. 1.5–2 mabove the base of the member.

Fig. 37. Typical sedimentary cycle in the Shepherd’s Chine Member (upper Vectis Formation) with facies style in scour and inter-scour areas along a major erosion surface,

distribution of main faunal groups and bioturbation, and interpretation of the lithofacies. ‘Fluvial’ refers to fluvial flood; ‘storm’ refers to wave/current generated turbulence

(after Stewart et al., 1991, fig. 5).


Approximately 18 m above the base of the member, ostracods(Theriosynoecum fittoni and Cypridea) regain abundance withinshaly mudstones of division C, locally infilling shallow polygonalmudcracks. These are overlain by the lowest of several tabularsharp-based ferroan calcite-cemented coquinas (up to c. 0.1 mthick), traceable throughout the section (Radley and Barker, 1998a,2000a; Figs. 10, 12 and 27). This layer comprises partly compactedand pyritized, predominantly disarticulated and variably orientedFilosina gregaria, scattered Viviparus infracretacicus, fish debris andostracods. The base preserves small U-shaped burrows (Diplocra-

terion parallelum), possible Planolites and casts of mudcracks andtool-marks. Theropod dinosaur footcasts on the base of the bed atShepherd’s Chine (SZ 447798) comprise pyritic Viviparus biospariteenclosing concentrations of fully articulated Filosina (Fig. 38).Tracks of a smaller ornithopod dinosaur occur at this level a shortdistance to the south-east (Radley et al., 1998a). The limestone andassociated shale yield dinocysts (Vesperopsis fragilis, Loboniella

hirsuta, Corculodinium uniconicum, Valensiella (ex Cassiculosphaer-

idia) parvulum), rare chlorococcalean algae (Tetraedron paraincus,Botryococcus sp.), brown wood fragments and sheet-like planttissue (Radley et al., 1998a).

Supervening ostracodal paper-shales (c. 3.5 m thick) containpavements of crushed aragonitic Viviparus infracretacicus andexhibit a mudcracked upper surface. This is overlain by a thin (10–20 mm) slightly glauconitic sandy limestone packed with dis-articulated Filosina and worn fish debris including hybodontidshark teeth. This and higher limestones (see below) have yieldedreworked Upper Jurassic (predominantly Kimmeridgian) dinocystsand amorphous organic matter (I.C. Harding, personal communi-cation). Supervening grey shales (1 m thick) contain pavements ofCypridea, Viviparus infracretacicus and Filosina.

The overlying 7 m interval is characterized by small-scalefining-upward cycles, denoting division D of Stewart et al. (1991).

The overlying ostracodal shales (c. 3 m) are capped by lenses ofmuddy limestone (up to about 50 mm thick) containing gastro-pods (Paraglauconia fittoni (Fig. 11), Procerithium (Rhabdocolpus) cf.rugosum and a smooth procerithiid or thiarid), bivalves (Praeex-

ogyra cf. distorta and Filosina gregaria). These mark the base ofdivision E (Fig. 12).

Overlying the limestone, two thin (c. 50 mm) clay-ironstonebeds are separated by shales (0.3 m) containing plant debris,foraminifera (Ammobaculites obliquus; Fig. 39), ostracods (includ-ing Paranotacythere inversa), gastropods (Procerithium sp. andViviparus infracretacicus) and bivalves (Filosina, Cuneocorbula cf.arkelli, and Nemocardium (Pratulum) ibbetsoni; Fig. 27). Bivalves arecommonly articulated on some laminae and occasionally pre-served in inferred life position. The higher ironstone (termedDiplocraterion ironstone; Fig. 12) is penetrated by well-preservedDiplocraterion parallelum, and truncated by a Filosina and oyster-strewn erosion surface (Stewart, 1978a, 1981a; Radley, 1994b;Goldring et al., 2005). An oyster-encrusted partial Iguanodon

skeleton has been recovered from this level (J.D. Radley, personalobservation). Void fills within one of the vertebrae consist of mud(black, grey or phosphatized), pyrite, siderite, calcite, sphaleriteand barite (Clarke, 1991, 2004; Clarke and Barker, 1993; Barkeret al., 1997a). The overlying shaly mudstones (c. 1 m) containscattered Paraglauconia, Praeexogyra, agglutinated foraminifera(Fig. 39) and scoured lenses of minute fragmentary sandstonetubes, possibly reworked Diplocraterion ichnoclasts.

The highest 10 m of the Shepherd’s Chine Member (division F;Fig. 12) are dominated by blocky grey mudstones with silt lenses. Amudcracked surface occurs approximately 3 m above the Diplo-

craterion ironstone (S. Hesselbo, personal communication). Therippled upper surface of a thin pyritic sandstone 4–5 m below thetop of the member preserves pyritized Praeexogyra and Viviparus.Closely above, the highest limestone (40–50 mm thick) consists of

Fig. 38. Theropod dinosaur footcast preserved on base of lowest limestone unit within the Shepherd’s Chine Member (upper Vectis Formation), Cowleaze Chine (Compton

Bay–Brighstone Bay GCR site, Isle of Wight). Ruler is graduated in cm. Specimen is held in the collection of Dinosaur Isle, Sandown, Isle of Wight.


Filosina with rarer Viviparus infracretacicus, a worn and boredexogyrid oyster (possibly referable to Aetostreon or Ceratostreon)and fish debris. Seams of fibrous calcite are locally cemented to theupper and lower surfaces of this bed. To the best of our knowledgethe oyster is the first authenticated record of a truly marinemollusc from the Wealden of southern England.

Dinocysts from 5 m below the top of the member includeAustralisphaera fragilis, associated with chlorococcalean algae(Scenedesmus, Tetraedron and Tetrastrum) and finely dividedamorphous detritus (Batten and Lister, 1988b). The highest metrebeneath the erosively based Perna Beds consists of black mudstone(Fig. 27) with scattered pyrite nodules, small, thin-shelled oystersand aragonitic cassiopid gastropods (Paraglauconia cf. fittoni;Figs. 10 and 12).


The bipartite nature of the Wealden Group on the Isle of Wightwas recognized during the first half of the nineteenth century(Fitton, 1824, 1836). However, early workers (Fitton, 1836; Reidand Strahan, 1889) also suspected the presence of two distinctsuccessions of Vectis ‘aspect’ west of Hanover Point, due to theabnormally thin nature of the westernmost succession (ComptonBay; Fig. 28). This notion was dispelled by the discovery ofthe Small Chine Fault (Colenutt and Hooley, 1906; White, 1921).The dramatic south-east to north-west thinning might be due to

the proximity of the faulted basin margin, immediately to thenorth (Wach and Ruffell, 1991; Radley and Barker, 1998a).

Subsurface evidence proves that the Wealden Group isapproximately 520 m thick beneath the southern part of the Isleof Wight (Falcon and Kent, 1960; Stewart, 1981a). Hamblin et al.(1992) recorded Wealden sediments up to 480 m thick fromoffshore wells south of the island. The oldest beds are apparentlycharacterized by a larger proportion of coarse-grained sand-bodiesthan are seen in the exposed succession (Stewart, 1981a),suggesting initial establishment of braidplain environmentsfollowing late Berriasian Cornubian uplift (Fig. 9). Advancedgeomorphic decay of the Cornubian massif by Barremian times canbe held to explain the meanderplain origin of the exposedsuccession (Stewart, 1978a, 1981a,b, 1983; Allen, 1981, 1998;Wright et al., 2000; Sweetman and Insole, 2010; Fig. 8). Theoxidized mudstones represent overbank sediments. Ferruginousnodules, poorly developed calcretes, widespread colour mottling,mudcracks, pseudoanticlines, slickensiding and palynomorphdestruction resulted from pedogenesis on the meanderplains.

Wright et al. (2000) drew attention to analogues of the Wessexpalaeosols in present-day tropical and subtropical seasonalwetland settings. Drying and wetting-upward transitions havebeen identified, reflecting aggradation of the floodplain andchanges in flooding duration. The predominance of simplemottling fabrics suggests high depositional rates. Varicoloured

Fig. 39. Agglutinated foraminifera from approximately 30 cm below to 1 m above the Diplocraterion ironstone, Shepherd’s Chine Member (upper Vectis Formation), south-

east of Shepherd’s Chine, Brighstone Bay, Isle of Wight (Compton Bay–Brighstone Bay GCR site). (a–d) Ammobaculites obliquus. (e–f) Textularia pulchella. Approximate lengths

in mm: a = 1, b = 0.65, c = 1, d = 0.9, e = 0.3, f = 0.25

(Radley, 1994b; reproduced by permission of Elsevier).


mudstones represent gley and pseudo-gley soils formed inseasonally waterlogged areas. Haematitic red mudstones resemblevertisols with swelling and shrinkage features typical of moderncounterparts in warm semi-arid regions: undulations, poorbedding due to ‘self-ploughing’, and slickensides. The redmudstones are thought to have formed on slightly elevated areaswhich underwent only occasional flooding. Rootlet traces indicateopen vegetation cover and calcrete nodules confirm a warm to hot,periodically wet regime. The nodules are small and localized, asmight be expected in a rapidly accreting low-carbonate alluvialplain. Wright et al. (2000) developed a model for the formation ofthese palaeosols, controlled by seasonal flooding period and minorvariations of relief on the Wessex floodplain (Fig. 40).

The average d13C value for the Wessex Formation calcretessuggests that pedogenic carbonate formed from C3-dominatedvegetation, with low ingress of atmospheric carbon dioxide. Thiscontrasts with the Upper Weald Clay calcretes (Ockley site,Weald Sub-basin) which indicate waterlogged marshy settingswhere ingress of atmospheric CO2 into soil was reduced(Robinson et al., 2002). Robinson and his co-workers estimateda pCO2 of 560 ppm for the Barremian, corresponding closely toresults obtained by Haworth et al. (2005) through assessment ofthe stomatal characters of the Wealden conifer Pseudofrenelopsis

parceramosa.

Red mudstones with concentrations of large unionoid pond-mussels in inferred life position are interpreted as desiccated pondfills. Scattered, predominantly disarticulated to partly articulatedskeletons of aquatic and terrestrial reptiles in mudstone unitsreflect generally high rates of weathering and predation on thefloodplains, punctuated by floods (Insole and Hutt, 1994). The palecolouration of the enclosed bones reflects oxidation of organicmaterial, probably due to atmospheric weathering and intenseultraviolet light during prolonged subaerial exposure (Martill andNaish, 2001). Long hot dry periods are indicated (several monthsduration, not necessarily seasonal), alternating with very wetspells confirming the variable-discharge regime deduced from thechannel deposits (Stewart, 1981b, 1983). In principle, conditionswere right for the neoformation of mixed-layer mudstones, but theblurring effect of alluvial changes must have obscured much of theevidence bearing on short-term climatic variation.

Topographic lows between channels (including abandonedchannels and ponds) were often filled with flood-borne intraclasts,mud and biogenic debris (Fig. 8). These materials often comprisepoorly sorted, matrix-rich conglomeratic units. The ligniticvarieties form plant debris beds (Oldham, 1976; Wright et al.,2000) which appear to have been deposited principally as debrisflows that incorporated biogenic and non-biogenic floodplainmaterials (Insole and Hutt, 1994; Radley and Barker, 2000b;

Fig. 40. Model for Wealden seasonal wetlands (Wessex Formation of the Isle of Wight). Grey-green mudstones and plant debris beds formed in ponds that were probably

mainly submerged; the mottled mudstones formed in topographically slightly higher areas that were flooded for a large part of the year; the red mudstones represent more

elevated areas that were flooded for only a short period of each year (after Wright et al., 2000, fig. 11).


Sweetman and Insole, 2010). Thicker, finer grained versions of thelatter probably accumulated in relatively long-standing stagnantponds and channels. Wright et al. (2000) compared these withpresent-day Australian ‘billabongs’ (Fig. 40), and which probablyfunctioned as dry-season refuges for molluscs, fish, crocodiles andturtles, attracting herbivorous, predatory and scavenging dino-saurs. Goethite occurrences in these beds suggest periodicdesiccation. The mixed, variably preserved aquatic-terrestrialbiota of the plant debris beds therefore represent a combinationof pond elements, allochthonous flood input from surroundingfloodplains and opportunistic scavengers (Insole and Hutt, 1994;Radley and Barker, 2000b; Martill and Naish, 2001; Sweetman andInsole, 2010). The dark colouration of the bones from these beds isthought to reflect the preservation of organic material throughrapid burial and subsequent pyritisation (Martill and Naish, 2001).Few if any aquatic plants like the horsetails of the Weald Sub-basinappear to be known.

The unionoid bivalves (Fig. 11) are elements of a stablefreshwater assemblage (Fig. 23). Taxonomic links may exist withassemblages in the Weald Clay Group of the Weald Sub-basin,south-east England (Morter, 1978) and with broadly contempora-neous non-marine strata in France, Spain, Germany, Morocco, theUnited States and the Far East (Mongin, 1961; Barker et al., 1997b;Radley et al., 2006; Delvene and Araujo, 2009; Delvene and Munt,2011). Initial studies of shell growth lines (Allen, 1998; Radley andBarker, 2000b) indicate regular variations in runoff. Dissolutionscars on the shell surfaces reflect acid leaching of soils onintrabasinal highs and nearby massifs.

Some of the wood in the plant debris beds is burnt, signifyingwildfires on the meanderplains and adjacent hinterland. The firespresumably broke out most often during the dry seasons recordedby annual rings in the woods and adaptations to drought (Francis,1987; Watson and Alvin, 1996; Allen, 1998). Remains of largeforest trees (e.g. Pseudofrenelopsis) indicate well-drained areas,possibly including sandy elevations on the floodplains. Floraldiversity is low relative to that of the lower Ashdown floodplains ofthe Weald Sub-basin (late Berriasian Fairlight flora; Hastings-PettLevel site). A long-term trend towards more frequent and extensivewildfires might be indicated, suggesting increasing aridity and/orlonger hot dry periods. If proved, this could have led to Ruffell andBatten’s proposed Barremian–Aptian arid phase (Ruffell andBatten, 1990).

Detrital petrography indicates that eastern Cornubia (Fig. 3)exposed mainly Permian-Triassic red beds with fringing Jurassic

sediments (Fig. 9). Granite was not exposed. Leaching decolourizedsome of the soil debris, rainfall was high and occasional heavystorms may have flooded almost the entire Wessex–Weald Basin.These could provide petrological avenues to correlation and datingbetween the Wessex and Weald sub-basins (Allen and Wimbledon,1991). Jurassic clasts (some recycled as gastroliths) imply sourcesalong the Isle of Wight–Portsdown High and/or more distant faultscarps fringing Cornubia (Figs. 7 and 9). The stratigraphic range ofthe calcareous nannofossils noted above is from Bajocian (MiddleJurassic) to Maastrichtian (Upper Cretaceous) (Bown and Cooper,1998). Given their strongly etched preservation, they are alsoprobably reworked from older strata.

The Pine Raft (Hanover Point Sandstone) at the base of theexposed succession (Figs. 6 and 29) could represent debris from alog-jam that developed during heavy rain and then collapsed afterponding back considerable bodies of water (Allen, 1998).Palynological data (Hughes and McDougall, 1990a; Hughes,1994) suggest that the unit may be a distal part of the CoarseQuartz Grit flood deposit upstream to the west (Dorset sites), andthat it might be chronostratigraphically close to the Hauterivian–Barremian boundary (Figs. 5 and 6). Robinson and Hesselbo’s(2004) fossil wood carbon-isotope curve has allowed tentativecorrelation with a composite Tethyan carbonate carbon-isotopecurve. This has provided an alternative correlation, suggesting thatthe Coarse Quartz Grit is older, possibly mid-late Hauterivian. Thehigh kaolinite content of mudstones associated with the Pine Raftsuggests derivation from strongly leached soils (Allen, 1998).

Fining-upward sand bodies with lateral accretion surfaces areprobably point-bars, deposited by mixed-load meanderingstreams (Stewart, 1981b). The Sudmoor Point Sandstone(Figs. 25, 32 and 35) is seen as several adjacent point-bars, partlytruncated by an abandoned meander-fill. Muddy laterally accretedunits are also probably point-bars, deposited by streams with highsuspension loads (Stewart, 1983). Current vectors from thechannel sands indicate derivation from the west or south-west(Stewart, 1978a), agreeing with their Cornubian petrographies.Thinner sand-bodies resemble crevasse splays. Beaconites-bur-rowed examples may have been reworked in shallow lacustrineenvironments (Goldring and Pollard, 1995). Widespread trackwaysrecord dinosaurs swarming on the Wessex floodplains, at leastseasonally. In some cases track preservation was achieved throughrapid burial beneath crevasse splay sands. Some of the moredistorted dinosaur footcasts may have originated as transmitted‘undertracks’. Coarse-grained sands (Compton Grange Sandstone;

Fig. 41. Palaeogeographic sketch of inferred Vectis Formation (Barremian up to

early Aptian) palaeoenvironments for the Isle of Wight and Wessex Sub-basin.

North direction is essentially conjectural but related to the line of the Purbeck–Isle

of Wight structure. 1 = low gradient coastal alluvial plain (Wessex Formation

meanderplain). 2 = reworked delta sands (top Barnes High Sandstone). 3 = delta

undergoing abandonment. 4 = inner lagoon shore (White rock). 5 = new delta.

6 = coastal lakes (Cowleaze Chine Member). 7 = Viviparus (Cowleaze Chine

Member). 8 = shallow bay with mud flats; feebly brackish (Cowleaze Chine

Member). 9 = delta (Barnes High Sandstone). 10 = reworked delta sand with mud

flats. 11 = broad shallow brackish lagoon (Shepherd’s Chine Member). 12 = Filosina

swept into deeper water by storms. 13 = possible growth fault at Compton Bay

(Stewart et al., 1991, fig. 12, reproduced by permission of Elsevier).


Fig. 24) reminiscent of lithologies seen at Swanage and sites furtherwest, suggest a westward-coarsening facies gradient.

Palygorskite in the highest part of the Wessex Formation hasbeen held to support the concept of increasing aridity towards theclose of Wessex times (Ruffell and Batten, 1990). A volcanogenicorigin cannot be ruled out (Allen, 1998). Stewart (1978b) likenedthe rippled, Beaconites-burrowed sandstones in the highest beds topresent-day Mississippi delta levee overspills, reworked by waveaction in shallow water. Closely comparable sandstones charac-terize alluvial phases of the Weald Clay (Weald Sub-basin), forexample BGS Bed 3 (Clock House Sandstone) at Capel and parts ofBGS Bed 5c (Alfold Sand) at Ockley, Surrey. Flow vectors fromchannels within the highest beds can be held to support Cornubianand Armorican sources. R.A. Coram (personal communication) hasattributed the concentration of near-complete Hypsilophodon

skeletons at the top of the Wessex Formation to mass drowningof a herd during a flood, followed by rapid burial in overbank mud.

Precise correlation with other sections exposing the WessexFormation is usually made difficult by the strongly lenticulargeometries of the constituent units. Stewart (1978a) suggestedthat the Hanover Point Sandstone might equate with the BrookSandstone and Sudmoor Point Sandstone. Carbon-isotope stratig-raphy suggests that the overall average sedimentation rates of theHanover Point and Brighstone Bay successions were similar(Robinson and Hesselbo, 2004). Taken as a whole, the sedimentsindicate deposition in a mosaic of distal meanderplain environ-ments influenced by a warm to very hot seasonal climate ofMediterranean rather than monsoonal type. During the roughly 5–10 million years represented by the Wessex Formation succession,the scene changed little apart from short-term variations (local orseasonal) typical of Mediterranean climate and fluctuations arisingfrom sedimentological processes normal in a subsiding basin withmildly active margins and a fairly stable sea-level.

Further west, substantial parts of the Swanage Bay successionare developed as similar lithofacies, while the most westerly sites(Mupe Bay–Worbarrow Bay, Lulworth Cove, Durdle Door) showhigher coarse sand and pebble contents. This indicates a lateraltransition to braided stream and even proximal fan facies towardsthe Cornubian foothills (Fig. 9). North-eastwards beyond the Isle ofWight–Portsdown High, roughly contemporaneous beds in theWeald Sub-basin (Upper Weald Clay) are mainly fossiliferousmudstones, silts and sands, more closely comparable with theVectis Formation. Periodic spread of Wessex alluvium into theWeald Clay lakes and lagoons is confirmed by recognition ofCornubian-sourced arenaceous members and associated pedo-genically altered mudstones (e.g. Capel and Ockley sites). Earlier inthe Weald Sub-basin, the Berriasian lower Ashdown Beds(Hastings–Pett Level site) and the Valanginian Upper TunbridgeWells Sand (Horsted Keynes site) had also developed mean-derplain facies partly reminiscent of the Wessex Formation.

The Cowleaze Chine Member marks the spread of coastallagoonal environments into the Wessex Sub-basin (Fig. 41). Ruffell(1988) suggested a late Barremian age for this event, possiblyconfirmed by the charophyte data (Feist et al., 1995). Thetransgression may be due to eustatic sea-level rise (Ruffell,1988) combined with differential decay of and/or reduction inthe sediment flux prior to the main Aptian (Lower Greensand)marine transgression. A climatic cause is also plausible, involvingwestward drift or spread of a dry Eurasian zone across the southernEnglish depocentres (Allen, 1998).

The Vectis Formation shows a high degree of lateral uniformityrelative to the underlying alluvial strata (Stewart, 1978a; Radleyand Barker, 1998a). This reflects the establishment of an open,laterally homogeneous depositional regime as the water-bodyexpanded and wave-fetch increased (Fig. 41). Nevertheless,pervasive but variable winnowing and time-averaging of the

dominantly argillaceous facies (Ruffell, 1988; Radley and Barker,2000a) may have masked much small-scale variability in time andspace, as evidenced by ostracod ‘faunicycles’ (Horne, 1995),sedimentological ‘windows’ preserved beneath storm beds (Allen,1998; Radley and Barker, 2000a) and perhaps void fills withinreptile bones (Clarke, 1991).

Pebbly developments at the base of the Cowleaze ChineMember are interpreted as lagoon shoreline deposits, margininga low sandy elevation. The highest part of the basal bed nearCowleaze Chine (White rock) resembles a crevasse splay, and waslatterly colonized by plants. Widespread development of palesands (Fig. 33) suggests that exposure was occasionally longenough to result in mild leaching. Moderate rates of trampling bylarge herbivorous dinosaurs suggest a relatively high productivityenvironment, fringing the retreating Wessex meanderplains(Radley et al., 1998a).

The lithofacies of the remaining beds of the Cowleaze ChineMember indicate deposition of essentially dysaerobic muds largelyor wholly in a subaqueous environment. Shell pavements in thelower part of the member demonstrate phases of wave or currentwinnowing, possibly due to distant storm influence. The faunadominated by Filosina gregaria and Viviparus infracretacicus alsocharacterizes BGS Bed 2 of the Lower Weald Clay (late Hauterivian)in the Weald Sub-basin (Warnham and Capel sites). There it istaken to indicate environmentally stressed, fluctuating freshwa-ter-oligohaline conditions. The Cowleaze Chine biota suggests lowsalinity excursions in the Wessex Sub-basin for the first time sinceBerriasian (Purbeck Group) times (Batten, 2002; Radley, 2002;Figs. 23 and 42). Stewart et al. (1991) inferred open marineenvironments beyond barrier islands to the east of the Vectislagoon (Fig. 41), mainly through recognition of onshore–offshorefacies gradients eastward across the sub-basin (Stewart, 1981a;Ruffell and Batten, 1994). The salinity fluctuations may thereforeindicate a distal marine influence.


Most Vectis ostracods probably inhabited fresh or slightlybrackish water. Formerly taken to signify freshwater or slightlysaline environments (Anderson et al., 1967; Anderson and Bazley,1971), cypridoidean-dominated assemblages possibly reflectphases when ephemeral water-bodies dominated. Conversely,non-cypridoideans may reflect periods when permanent water-bodies prevailed (Horne, 1995). Wealden dinocyst assemblages arenow known to include many low-salinity taxa (Batten and Lister,1988a,b). Amongst these, Vesperopsis fragilis also occurs in themarine late Hauterivian–Barremian of eastern England, indicatingstrongly euryhaline conditions (Harding and Allen, 1995).

The overall coarsening-upward Barnes High Sandstone succes-sion, seen between Barnes High and Cowleaze Chine, points to ageneral upward increase in flow energy, punctuated by slack-water episodes during which mud settled. Stewart (1978a)considered several models and favoured a progradational rivermouth bar origin (also see Daley and Stewart, 1979; Ruffell, 1988;Stewart et al., 1991; Fig. 41). Stewart asserted that the abundantlenticular and wavy bedding could be due to tidal influence and/ordaily and seasonal fluctuations in discharge. The latter scenario issupported by trace fossil evidence (Radley et al., 1998b) andclimatic modelling (Allen, 1998). Better sorted, megarippled andsymmetrically rippled sands, conglomerates and dinosaur tracks atthe top of the member suggest shallow water reworking followingabandonment. The thinner sand-bodies seen at Shippards Chineand Compton Bay have been interpreted as small coastal bars(Stewart, 1978a) or flood-deposited deltas (Wach and Ruffell,1991).

Fig. 42. Inferred salinity changes through the Vectis Formation (Barremian up to early Ap

Radley and Barker (1998a, fig. 7).

Yoshida et al. (2001) proposed an origin for the Barnes HighSandstone as part of a sandbar complex within a tidal estuary (alsosee Jackson et al., 2003). The attenuation of the member betweenShippards Chine and Barnes High was taken to indicate estuarydevelopment within a fault-bounded valley adjacent to thenorthern margin of the Wessex Sub-basin. Attention was drawnto the erosion surface flooring the member between Barnes Highand Cowleaze Chine, and the scarcity of putative tidal sedimentarystructures in the Cowleaze Chine Member below, and theirabundance above. Tracing this surface from Sandown Bay toShippards Chine, they interpreted it as a composite sequenceboundary and a transgressive surface, which separates a loweralluvial and microtidal lagoonal sequence (Wessex Formation andCowleaze Chine Member) from an upper mesotidal to lowmacrotidal estuarine sequence (Barnes High Sandstone andShepherd’s Chine members).

Yoshida and his co-workers envisaged the Barnes HighSandstone at Shippards Chine as alternating channel plug or innerestuary muds, and inner estuary tidal fluvial channel sands. Theextensive channelisation was tentatively attributed to fluvial andebb-dominated tidal processes. To the south-east (Barnes High toCowleaze Chine), the Barnes High Sandstone was interpreted byYoshida and co-workers as a tidal bar complex; the large-scaleaccretion surfaces in the higher part indicating migration towardsthe north-west. The lenticular and wavy bedded lower sedimentswere modelled as distal bar and inter-bar sediments in an inner,subtidal, estuarine environment. The overlying cross-beddedfacies were envisaged as the middle to upper parts of coalesced

tian) of the Compton Bay–Brighstone Bay GCR site, based on molluscan faunas. After


tidal bars; the highest beds (shelly, symmetrically and waverippled) representing intertidal bar-top sands. The reduction inthickness of the succession here and the presence of a mudcrackedhorizon in the uppermost Cowleaze Chine Member were taken toindicate deposition on an intra-valley high.

While this model resolves problems concerning currentdirections (sand-body progradation towards the inferred clasticsources; see Stewart et al., 1991), it is weakened by discrepancieswithin the half-graben model such as relatively thin successions ofBarnes High Sandstone adjacent to the sub-basin margin atCompton Bay and Sandown Bay, inconclusive evidence for lunartidality, the two-dimensional, scattered nature of the sections andthe probable absence of a basal erosion surface throughout muchof the Island (Stewart, 1978a; Wach and Ruffell, 1991).

Stewart (1978a) further compared the Barnes High Sandstonewith the minor coarsening-upward members in the Hastings Bedsof the Weald Sub-basin, now envisaged mainly as small fan-deltas(e.g. Cliff End Sand at the Hastings–Pett Level site). Stewart et al.(1991) also compared the Barnes High Sandstone to the Alfold SandMember of the Upper Weald Clay (BGS Bed 5c, seen at the Ockleysite, Surrey), now thought to represent interbedded overbank andlacustrine sediments.

The Shepherd’s Chine Member is developed in broadly similar,dysaerobic mudstone and silt facies to the Cowleaze ChineMember. Spreads of burnt ferns near the base point to flood inputfrom fire-climax communities (Harris, 1981; Watson and Alvin,1996) in a fire-prone coastal plain setting (Collinson et al., 2000),confirming a hot, periodically wet climate (Allen, 1998). Ruffell(1988) originally proposed a salinity and oxygen stratified modelfor the Shepherd’s Chine Member but a simpler scenario isfavoured here. The high degree of lateral uniformity and evidencefor widespread shallow water, local emergence and predominantlylow salinities support the concept of a partly enclosed coastallagoon, bordered by periodically flooded mudflats (Stewart et al.,1991; Wach and Ruffell, 1991; Radley and Barker, 2000a; Fig. 41).Yoshida et al. (2001) reinterpreted the lower and middle parts ofthe Shepherd’s Chine Member as subtidal bayfill muds within acentral estuarine basin. This scenario is weakened by evidence forwidespread emergence, ambiguity of the proposed putative tidalindicators (Stewart, 1978a; Stewart et al., 1991; Radley and Barker,2000a), and weaknesses of the overall estuarine model developedfor the underlying Barnes High Sandstone (see above).

The minor fining-upward cycles (Figs. 34 and 37) are attributedto distal deltaic advance and retreat (Stewart et al., 1991). North-east/south-west oriented gutters and other scours in their lowerparts may therefore signify fluvial runoff (Daley and Stewart,1979; Stewart, 1981a; Allen, 1998). However, the scarce currentdata suggest north-eastward flow, adding some weight to anorigin through storm scouring (Stewart et al., 1991; Wach andRuffell, 1991). Steep-sided, terraced and flat-based gutters provethat the muds were relatively cohesive at the time of erosion. Thegutter casts are important repositories of hydrodynamicallysorted insect, vertebrate and plant remains (Twitchett, 1995),sometimes as several discrete pulses (Stewart et al., 1991).Significant differences from examples in the mudstone forma-tions of the Weald Sub-basin are the absence of extrabasinalpebbles (seen e.g. at the Cranleigh (Bookhurst Tileworks) site) andthe relative scarcity of tool marks amongst the sole structures (asseen at the Sharpthorne, Horsted Keynes, Philpots Quarry andCapel sites). However the closely comparable ichnofaunas on thegutter casts (Goldring et al., 2005) augment the sedimentological,isotopic and palaeontological evidence for similar overallpalaeoenvironments.

The higher parts of the fining-upward cycles demonstraterenewed mud deposition (Fig. 37). Wave and/or current activity,perhaps microtidally influenced, generated the lenticular bedding

(Wach and Ruffell, 1991). The muds were periodically colonized byshallow-infaunal to epifaunal molluscs and ostracods. Winnowing(possibly due to distal storm activity; Ruffell, 1988) reworked theskeletal materials into pavements. Such minor erosive events mayalso have been responsible for the repeated removal of bioturbatedsurficial sediment, now preserved solely beneath rapidly depositedcoquinas and gutter casts (Radley and Barker, 2000a and below).Upward decreasing bioturbation through the cycles (Stewart et al.,1991) indicates a trend towards dysaerobic conditions justbeneath sediment-water interfaces.

Biofabrics of the coquina beds (Figs. 20, 31 and 38) indicatedeposition by onshore-directed storms (Wach and Ruffell, 1991;Radley and Barker, 2000a). The presence of glauconite grains and aworn exogyrid oyster suggest marine washover, although evidencefor attendant salinity rise is normally lacking. Alternatively thesemarine constituents could have been reworked from landward‘terraces’ resulting from brief earlier episodes of sea-level rise.Mudcracked and/or dinosaur trampled surfaces beneath thecoquinas (Figs. 31 and 38) record periodically widespreademergence before flooding by storms. This suggests that the smallscale cyclicity might have been tectonically or climaticallycontrolled (Stewart et al., 1991). It is comparable in that respectwith the ‘Prentice’ rhythmicity of the Weald Clay (e.g. at theWarnham site, West Sussex). Minor fluctuations in water level andtherefore the extent of marginal mudflats were probablyinfluenced by wind-driven and barometric ‘seiches’ (Wach andRuffell, 1991; Radley et al., 1998a).

Salinities rose periodically during deposition of the upper partof the Shepherd’s Chine Member (Fig. 42), replacing the normal,low-salinity Viviparus–Filosina fauna (Fig. 23) with its distinctive,relatively diverse assemblage (Meyer, 1872; Jackson, 1933;Stewart, 1978a; Batten, 1982; Stewart et al., 1991; Radley andBarker, 1998a,b; Figs. 23 and 30). This fauna is also encountered inthe Weald Clay of the Weald Sub-basin (Warnham and Capel sites;Kilenyi and Allen, 1968; Morter, 1978; Radley, 1999; Radley et al.,2006). The corbulid and cardiid bivalves, oysters and procerithiidand cassiopid gastropods (Fig. 11) indicate fluctuating mesoha-line–brachyhaline conditions (Radley et al., 2006; Fig. 23). Theforaminifera (Fig. 39) could have been strongly euryhaline (Radley,1995). Floods of the ostracod Paranotacythere inversa (Radley,1994b; Radley and Barker, 1998a; Fig. 21) may signify transientfully marine connections with the Boreal marine Yorkshire Basin(Anderson, 1967; D. Horne, personal communication). However,the cassiopid gastropods also suggest a southern, Tethyan link(Cleevely and Morris, 1988). Confirmation of a marine larval stageamongst the cassiopids would prove exchange with open seawaterand therefore with fully marine environments. This is hinted at bythe apparent lack of acid-etched shells in the Shepherd’s ChineMember.

The increase in current/wave disturbance, storm events andmesohaline–brachyhaline phases indicates decreasing effective-ness of coastal barriers during latest Wealden times (Meyer, 1872;Allen, 1981), presaging the Lower Greensand transgression. Thismight have resulted from increased leakage, decreased fluvialinput, sea-level rise (possibly eustatic) or a combination of thesefactors. The widely distributed Diplocraterion-burrowed ironstonein the lowest quasi-marine horizon (Fig. 12) may be significant inthis respect, hinting at a marine flood (Goldring et al., 2005).Commonly articulated bivalves at the same level also point to alower energy, possibly deeper water setting but they could equallywell reflect an increase in sedimentation rate. As seen, sea-levelfluctuations could also have generated quasi-marine terraces(Radley and Barker, 2000a). Reworked oyster fragments in thehighest coquina might then signify terrace erosion following sea-level fall. However storm washover is equally plausible (seeabove).


Black, pyritic Paraglauconia-rich mudstones at the top of themember (Figs. 12 and 27) similarly suggest a deeper water quasi-marine environment, contrasting sharply with the underlying low-salinity, storm-influenced, mudflat facies (Radley and Barker,1998a). The dark-coloured shelly mudstones are traceable at thesame level across the Isle of Wight, implying little erosion beforedeposition of the fully marine Perna Beds in early Aptian(fissicostatus biozone) times. It is therefore likely that the upperpart of the Shepherd’s Chine Member is early Aptian in age (Figs. 5and 6), supporting Kerth and Hailwood’s (1988) magnetostrati-graphic interpretation.

Lagoonal environments had spread west into Dorset by lateVectis times (Swanage site). Sediments and faunas of Vectis aspectalso characterize the highest Weald Clay in the Weald Sub-basin(e.g. Cranleigh (Bookhurst Tileworks) site, Surrey). Thus the latestWealden scenes in both sub-basins were dominated by extensivemudflats bordering shallow, muddy coastal lagoonal complexes(Allen, 1989, 1998; Stewart et al., 1991; Radley, 1999; Fig. 13).Ruffell and Garden (1997) interpreted the increase in kaolinitefrom Atherfield towards Compton Bay as signifying increasingproximity to the erosive northern margin of the Wessex Sub-basin.On the eastern side of the Isle of Wight (Sandown Bay site), theupper Vectis succession differs chiefly in the greater abundance ofobvious late Jurassic detritus. This attests to the persistence of theIsle of Wight–Portsdown High as a partial barrier between theWessex and Weald depocentres throughout the Wealden (Figs. 4and 41).

10.2.4. Conclusions

The site superbly exposes a 250 m pile of fluvial-alluvial andcoastal lacustrine-lagoonal sediments, comprising the Wessex

Fig. 43. Cliff sections through Wessex Formation (Valanginian possibly up to early Aptian

of Ballard Cliff is visible beyond. Photograph courtesy of Rob Coram.

Formation below and Vectis Formation above. The extent andstratigraphic range of the site facilitates rigorous study of thelateral and vertical changes in the sedimentology of the complexlithofacies, and of the abundant plant and animal fossils therein.Sandstones and mudstones in both formations await detailedresearch on their petrography, geochemistry (including isotopicand organic), palaeobotany (including palynology) and palaeon-tology (invertebrate and vertebrate). The plant debris beds, guttercasts and bioclastic limestones in particular, are of outstandingimportance for further Wealden palaeobiological study. Partlyowing to rapid rates of coastal erosion, recent work on the site hasproduced many new discoveries of microfossils, molluscs, insects,vertebrates, and invertebrate and vertebrate ichnofossils. Manyawait formal description, and prospects for new discoveries aregood. Thus, there is great potential for further understanding of thepalaeobotany, palaeozoology, palaeoenvironments (including cli-matic/meteorological aspects) and palaeoecology of the WessexSub-basin between approximately 130 and 120 million years ago.

10.3. Swanage, Dorset (SZ 031795–SZ 039809)


Cliff and foreshore sections of the uppermost 450–500 m of theWessex Formation are traceable along the northern part ofSwanage Bay for 1.5 km, immediately south of the axis of thePurbeck Monocline (Figs. 2 and 43). A thin representative of theoverlying Vectis Formation occurs at Punfield Cove at the northernend of the section, but is only occasionally exposed.

Little detailed work had been undertaken on this site untilrecently, despite its accessibility and size. This was partly due tothe weathered, locally slipped and vegetated cliff sections, and to

) sandstones and mudstones, Swanage GCR site, Dorset. The Upper Cretaceous Chalk


difficulties of estimating thicknesses of the lenticular beds. Thesections have been noted by Webster (1816), Conybeare andPhillips (1822), Fitton (1824, 1836), Buckland and De la Beche(1836), Mantell (1827, 1848b), Fisher (1855), Lyell (1871),Godwin-Austen (1872), Hudleston and Morris (1882), Bates(1898), Monckton (1910), Arkell (1934, 1938), Kirkaldy (1939),Butler (1998) and Robinson and Hesselbo (2004). The relativelyfossiliferous uppermost beds (Vectis Formation) were firstdocumented by Fitton (1836), Judd (1871), Meyer (1873) andHudleston and Morris (1882), and most recently by Ruffell andBatten (1994). Radley (2005) summarized their derived fossilcontent. Strahan (1898) and Arkell (1947) provided detailedaccounts of the succession as a whole, and outlined the lithologiespresent. The site’s geology was briefly summarized by House(1993) and noted by Radley (2006).

Groves (1931) undertook an important petrographic study ofthe Wessex Formation and the clay mineralogy was documentedby Allen (1998). Stewart (1978a) provided notes on the sedimen-tology of the Wessex Formation with special reference tosandstone beds. Robinson et al. (2002) studied the stable-isotopegeochemistry of calcrete nodules from a palaeosol. Macroscopicplant remains were studied by Oldham (1976) and Watson et al.(2001), and the sparse bivalve faunas by Radley (1997b, 2002).Vertebrate fossils have been noted by several workers, includingBuckland and De la Beche (1836), Fitton (1836) and Mansel-Pleydell (1888). Dinosaur tracks were recorded by Beckles (1862)and Mansel-Pleydell. The ichnofauna as a whole was documentedby Goldring et al. (2005). The ostracods of the Vectis Formationwere documented by Fitton (1836), Jones (1878, 1888), Sohn andAnderson (1964), Anderson (1967, 1985) and Wilkinson (2002).

10.3.2. Description

10.3.2.1. Wessex Formation. The cliff and foreshore sections ofnorthern Swanage Bay (SZ 031797–039809; Fig. 43) expose up toabout 350 m of varicoloured mudstones, fine to coarse-grainedsandstones, ironstones and lignitic plant debris beds. TheGeological Conservation Review site boundary extends south (SZ031795) to include an intertidally exposed sandstone with ‘Unio’ cf.porrectus, about 450 m below the top of the formation. This lieswithin a poorly exposed mudstone-dominated succession, thoughtto form much of the lower Wealden at Swanage (C.P. Palmer,personal communication).

The mudstones (up to several metres thick) of the main cliffsection display probable rootlet structures and at least onehorizon of calcrete nodules (Robinson et al., 2002). The latter havesupplied average d13C values of �9.1% and average d18O values of�2.2%. The sand bodies reach approximately 6 m in thickness,some fining upwards and displaying trough cross-bedding,synsedimentary deformation, lateral accretion surfaces (Stewart,1978a), intraclastic lenses and Beaconites burrows. Groves (1931)recorded tourmaline, zircon, topaz, brookite, anatase, muscovite,biotite and cassiterite from two sandstone beds. Current direc-tions from the sandstones indicate flow from the west or south-west.

Coarse pebbly sandstones (quartz rudites) occur approximately310 m and 120 m below the top of the formation (C.P. Palmer,personal communication). Arkell (1947) recognized only the lowerhorizon (about 1 m thick) which he correlated with the CoarseQuartz Grit of the Durdle Door–Worbarrow Bay sites to the west(also see Robinson and Hesselbo, 2004). The bed contains abundanttourmaliniferous (including metasedimentary) clasts and grains ofK-feldspar, tourmaline, traces of staurolite and rarer kyanite, andPortlandian (Upper Jurassic) glauconite. Work on the sand fraction(Allen, 1972 and unpublished results) confirms the overwhelmingpredominance of Cornubian materials (K-feldspar 6%, tourmaline

38% (fine aggregates 33%)) over Armorican and other(staurolite < 0.1%, kyanite < 0.1%, glauconite < 0.5%) in the heavysuite. 40Ar/39Ar ages of the tourmalines span late Precambrian tomid-Carboniferous. The clay fractions (19 horizons) are dominatedby illite–smectite (35–59%), illite (14–41%) and kaolinite (11–49%).Smectite and palygorskite have not been detected.

The plant debris beds contain lignitized logs, fragments offusain (Stewart, 1978a), gymnospermous cuticle (Oldham, 1976;Watson et al., 2001) and amber (R.A. Coram, personal communi-cation), also conifer fronds, fish teeth (Lepidotes) and bones ofcrocodiles and dinosaurs (Mansel-Pleydell, 1888; R.A. Coram,personal communication). C.P. Palmer (personal communication)recorded a probable gastrolith from pebbly sandstone approxi-mately 115 m below the top of the formation. Beckles (1862)recorded iguanodontid footcasts within two sandstone beds,approximately 6 m apart, around SZ 032799. These levels mustlie between 300 and 350 m below the top of the formation. Fitton(1836) noted bivalves (Unio), in concretionary sandstone at anunknown horizon, while Strahan (1898) and Arkell (1947) bothnoted Unio in ironstone in the higher part of the section. A largeunionoid, probably Margaritifera (Pseudunio) valdensis, occurs inintraclastic silty clay-ironstone approximately 140 m below thetop of the formation (Radley, 1997b). This is probably the horizonnoted by Strahan and Arkell.

10.3.2.2. Vectis Formation. This is approximately 10–12 m thick(Strahan, 1898; Ruffell and Batten, 1994) and comprises dark-coloured shales, silts, sandstones, fibrous calcite seams and at leastone bioclastic limestone bed. Fossils consist of ostracods (Cypridea

caudata, Cypridea fasciata, Cypridea tenuis, Cypridea valdensis andlectotype of Theriosynoecum fittoni), bivalves (Filosina, ‘Unio’,Praeexogyra) and gastropods (Viviparus). Palynological prepara-tions reveal spores, pollen, freshwater algae and dinocystsincluding reworked marine taxa of Upper Jurassic or LowerCretaceous age. These beds are absent at Worbarrow Bay,suggesting their westward replacement by alluvial facies.


‘Unio’ cf. porrectus in the lower part of the section suggests apre-Hauterivian age (Morter, 1978). Margaritifera (Pseudunio)valdensis, probably present within the higher beds, characterizesthe exposed Wessex Formation on the Isle of Wight (Compton Bay–Brighstone Bay site; Fig. 11) that is largely or wholly Barremian inage (Fig. 5). The lower coarse quartz grit horizon may correlatewith the Coarse Quartz Grit sensu stricto of the western sections(Arkell, 1947; Robinson and Hesselbo, 2004; Fig. 5), though recentmapping by the British Geological Survey (British GeologicalSurvey, 2000) indicates the presence of several discontinuouspebbly sandstone horizons between Swanage and the Corfe Castlearea, approximately 6 km inland. Palynological data suggests thatthe Coarse Quartz Grit sensu stricto (see Steeple, Mupe Bay–Worbarrow Bay, Lulworth Cove and Durdle Door sites) mightbroadly correlate with the Hauterivian–Barremian boundary andthe Pine Raft horizon on the Isle of Wight (Hughes and McDougall,1990a; Fig. 5) though fossil wood carbon-isotope data suggests anolder, probably mid-late Hauterivian age (Robinson and Hesselbo,2004). Interestingly, a ‘Coarse Quartz Grit’ horizon within theWealden was recognized in an offshore well approximately 10 kmeast of Swanage and 20 km west of the Isle of Wight (Ruffell, 1992).

In many respects the Wessex Formation resembles that on theIsle of Wight (Compton Bay–Brighstone Bay and Sandown Baysites) and likewise records a meanderplain setting but somewhatmore energetic. The varicoloured mudstones represent surface-water gleys formed in seasonally waterlogged areas. The lightcarbon-isotope and oxygen-isotope compositions of calcretenodules suggest that pedogenic carbonate formed from


C3-dominated vegetation, with limited ingress of atmosphericcarbon dioxide (Robinson et al., 2002).

Some of the intercalated sand bodies are probably point-bars,deposited by meandering mixed-load streams (Stewart, 1978a).The sands are commonly coarser than those seen on the Isle ofWight, but generally finer than those to the west. PebblyCornubian-sourced sandstones, constituting the ‘coarse quartzgrit’ horizons signify powerful unembanked floods, possiblytriggered by heavy storms and/or relatively rapid Cornubian uplift.

The plant debris beds are interpreted as floodplain debris thataccumulated in stagnant depressions during floods. The molluscs,fish, crocodile and dinosaur remains suggest that these topograph-ic lows functioned as biotic refuges, although at least some of thebiodebris is probably allochthonous. Fusain fragments indicatehinterland or floodplain wildfires, reflecting a ‘Mediterranean’ typeof climate with warm wet winters and hot dry summersinterrupted by brief rainy spells (Allen, 1998). Iguanodon track-ways amongst the overbank sediments prove similar dinosauractivity to that evidenced by the Isle of Wight sites.

The Vectis Formation signals the establishment of muddycoastal lagoonal conditions in latest Wealden times, possibly dueto eustatic sea-level rise (Ruffell, 1988). Ruffell and Batten (1994)noted the similarity of the succession to the middle part of theShepherd’s Chine Member (upper Vectis Formation, probably earlyAptian) of the Isle of Wight (Compton Bay–Brighstone Bay site).This correlation is supported by biostratigraphic evidence fromostracods (Anderson, 1967). Euryhaline bivalves (Filosina), fresh-water algae and dinocysts indicate fluctuating brackish salinitiesand limited marine influence, prior to the main Aptian marinetransgression.

10.3.4. Conclusions

The site provides the thickest continuous succession ofWealden sediments exposed anywhere in southern England. Inthe light of recent finds, prospects for further important fossildiscoveries are good, as well as for advancing knowledge of theenvironments (including climates) in which the animals and plantslived.

10.4. Steeple, Dorset (SY 911809) (potential GCR site)


The village of Steeple is situated on the northern limb of thePurbeck Monocline, 2 km north of Kimmeridge Bay (Fig. 2). The siteincludes now defunct sand pits near Steeple church, noted byStrahan (1898), Arkell (1947) and Oakley (1947). A pebblysandstone unit within the Wessex Formation was formerlyexposed here. The detrital petrography was researched by Kirkaldy(1947) and Oakley (1947). Oakley’s record of reworked micro-fossils was additionally noted by Haslett (1996) and Radley (2005).

10.4.2. Description

Although little is now exposed, the erstwhile pits once revealedpebbly sandstones dipping at 348 to the north (Arkell, 1947). Theseare at least 4.5 m thick, and dominated by clasts (up to 5 cm) ofquartz and quartzite, some apparently tourmaliniferous (Strahan,1898; W.J. Arkell and P. Allen, unpublished observations, 1957).Strahan also recorded lignite fragments.


The pebbly sandstone signifies a major flood or floods,generated on the Cornubian massif (Figs. 3, 9 and 13) by heavyrains. Recent mapping by the British Geological Survey (BritishGeological Survey, 2000) suggests that this unit correlates withthe Coarse Quartz Grit of the coastal sites to the west. Onpalynological grounds this unit might broadly correlate with the

Hauterivian–Barremian boundary (Hughes and McDougall,1990a, Fig. 5), though Robinson and Hesselbo’s (2004) fossilwood carbon-isotope data suggests an earlier, mid-late Hauter-ivian age. Petrographic studies of clasts from nearby coastal sites(e.g. Swanage) have revealed tourmaline-rich Cornubian compo-sitions (Allen, 1972, 1975).

10.4.4. Conclusions

Being in a key position between Swanage Bay and WorbarrowBay, the site justifies re-excavation.

10.5. Mupe Bay and Worbarrow Bay, Dorset (SY 843797–SY 843801,

SY 871796–SY 868801)


Cliff sections of the Wessex Formation occur at Mupe Bay (SY843797–843801), and 2.5 km further east on the eastern side ofWorbarrow Bay (SY 869800–SY 871798). Both sites are on thenorthern limb of the Purbeck Monocline (Fig. 2). The successionsare underlain by Berriasian Upper Purbeck Beds (seen at BaconHole (SY 839796–SY 843796) and on the north side of WorbarrowTout (SY 870796)) and capped by a thin development of AptianLower Greensand.

Principal interests are provided by the basal beds and overlyingoil-rich sediments at Mupe Bay (Lees and Cox, 1937; Selley andStoneley, 1987; Hesselbo and Allen, 1991; Miles et al., 1993;Kinghorn et al., 1994; Wimbledon et al., 1996; Bigge andFarrimond, 1998; Parfitt and Farrimond, 1998; Hesselbo, 1998;Hawkes et al., 1998; Underhill and Stoneley, 1998), and thedistinctive Coarse Quartz Grit at Worbarrow (Arkell, 1947;Stewart, 1978a; McMahon and Underhill, 1995; British GeologicalSurvey, 2000; Robinson and Hesselbo, 2004). The sections werebriefly noted for example by Conybeare and Phillips (1822), Fitton(1836), Judd (1871), Bates (1898), Monckton (1910), Arkell (1934,1938), Kirkaldy (1939) and Radley (2006), and described by Fitton(1824), Fisher (1855), Strahan (1898), Arkell (1947), Stewart(1978a), Nowell (1997, 2000) and Robinson and Hesselbo (2004).Nowell’s 1997 paper was discussed by Radley (1998) and Nowell(1998a). Following Groves’s (1931) petrographic study, sedimen-tological interpretations were given by Stewart (1978a), Selley andStoneley (1987), Allen (1989), Hesselbo and Allen (1991), Kinghornet al. (1994), Wimbledon et al. (1996) and Hesselbo (1998).Palynological studies were conducted by Hughes and Croxton(1973), Hughes and McDougall (1990a), Hughes (1994) and Ruffelland Batten (1994). Plant fossils have been documented by Oldham(1976), Watson and Harrison (1998), Watson et al. (2001), Watsonand Cusack (2005), Haworth et al. (2005) and Haworth andMcElwain (2008). Clay minerals were studied by Hallam et al.(1991), Allen (1998) and Jeans (2006). The invertebrate ichnofaunawas noted by Goldring et al. (2005) and dinosaur tracks by Mansel-Pleydell (1888) and Ensom (2009). Mansel-Pleydell additionallydiscovered dinosaur bones. Radley (2002) briefly mentioned themolluscan fossils.

10.5.2. Description

10.5.2.1. Mupe Bay. The Wessex Formation at Mupe Bay (Fig. 2) isapproximately 225 m thick and dips at 40–758 northwards. Itlargely comprises sandstones (frequently coarse-grained andpebbly), intercalated with silts, mudstones and plant debris beds.The basal 20–24 m exposed in low cliffs at the southern end of thebay are characterized by interlayered cross-stratified and rippledsandstones and mudstones, massive varicoloured mudstones andlaminated purple-grey mudstones (Hesselbo and Allen, 1991;Fig. 44). Interlayered sandstone–mudstone units are exemplifiedby the lowest sand body, displaying wavy bedding, flaser bedding,

Fig. 44. Vertical section through the basal Wessex Formation (Valanginian) at Mupe

Bay, Dorset (Mupe Bay and Worbarrow Bay GCR site). After Hesselbo and Allen

(1991, fig. 3).


tabular cross-bedding, soft sediment deformation and bioturba-tion. The laminated mudstone beneath the Oily Boulder Bed (seebelow; Fig. 45) exhibits sand laminae, silt dykelets, soft-sedimentdeformation and yields lignite and unionoid bivalves (Stewart,1978a).

Hallam et al. (1991) found that mixed-layer clay mineralsdisappear close to the top of the underlying Purbeck Group atMupe Bay, and smectite continues to decline. In the Wealden about3 m above, smectite disappears, and mixed-layer clay (maximumc. 30%) and chlorite (maximum c. 10%) resurge for a short intervalat the expense of illite (down to 13%). Both components apparentlydecline to roughly 4% through the next few metres up to the OilyBoulder Bed. Smectite (maximum c. 12%) together with mixed-layer and chloritic clay, disappears at about 3–4 m above. Thisleaves a mix of illite and kaolinite which reaches equality at

approximately 23 m above the Wealden base. Independentlyobtained data differs somewhat from that of Hallam and his co-workers. P. Allen and W.A. Wimbledon were unable to recognizeeither the drastic reduction in mixed-layer clay or the compensa-tory increase in illite at the Purbeck–Wealden junction. Discretesmectite reappears 3–4 m below the boulder bed but is absentfrom the bed itself, kaolinite being exceptionally high there (seebelow).

Approximately 24 m above the top of the Purbeck Group, theOily Boulder Bed (Fig. 45) comprises erosively based kaoliniticsandstone impregnated with light oil, above a lag of large (up to0.2 m long) oil-cemented sandstone clasts and lignitic logs. Thesandstone has a mean oil content of 2.7%; the clasts 7.5% (Parfittand Farrimond, 1998). The clasts possess jarositic skins and containless feldspar but more kaolinite than the matrix. Analysis of an oilglobule preserved within a clast indicates moderate maturity(Wimbledon et al., 1996). Prominent erosion surfaces occurapproximately 1.5 m below the Oily Boulder Bed, and at its base(Stewart, 1978a; Hesselbo and Allen, 1991).

Above, the remainder of the Wessex Formation is developed inthe typical sandstone and varicoloured illite/kaolinite-dominatedmudstone and sandstone facies of the Lulworth–Worbarrow area.Wimbledon et al. (1996) recorded northerly mean flow directionsfrom cross-laminated sandstones immediately above the OilyBoulder Bed and Lees and Cox (1937) noted a higher oil-impregnated sand. Thicker sand bodies (around 5 m thick) exhibittrough/planar cross-bedding and may fine upwards (Stewart,1978a). The Coarse Quartz Grit (approximately 6 m thick) occursapproximately 145 m above the base of the formation (Fig. 46).Palynological samples from immediately above and below yieldwell-preserved spores and pollen (Ruffell and Batten, 1994). A thin(50–80 mm) tabular ferruginous sandstone approximately 18 mabove the Coarse Quartz Grit contains vertical to subhorizontalBeaconites burrows (Goldring et al., 2005). Ruffell and Battenrecorded rootlet traces and plant debris from varicolouredmudstones at the top of the formation.

10.5.2.2. Worbarrow Bay. The Wessex Formation at WorbarrowBay (c. 418 m thick; Arkell, 1947) comprises varicolouredmudstones, dominantly coarse sandstones, ironstones and occa-sional plant debris beds (Figs. 47 and 48). Mudstones are generallydominated by kaolinite and illite (Jeans, 2006). Fossil wood iscommon throughout; some charcoalified, and has an averagecarbon-isotopic composition of approximately �23% (Robinsonand Hesselbo, 2004). Plant cuticle material has been collected(Oldham, 1976; Watson and Harrison, 1998; Watson et al., 2001;Haworth et al., 2005; Haworth and McElwain, 2008), includingPseudotorrelia linkii, Pseudofrenelopsis parceramosa and the holo-types of Czekanowskia anguae and Ginkgoites weatherwaxiae. Leaffragments of the latter species occasionally display partly repairedbite marks attributable to mandibulate insects (ichnogenusPhagophytichnus; Watson et al., 2001). Palynological assemblagesyield abundant spores and pollen (Hughes and Croxton, 1973;Hughes and McDougall, 1990a; Hughes, 1994). Amber fragmentsoccur in at least one plant debris bed (R.A. Coram, personalcommunication). The highest beds, including mudstones and finesandstones (Robinson and Hesselbo, 2004), yield a similarassemblage of freshwater algae to that of the late Barremianand/or early Aptian Vectis Formation at the Swanage Bay site(Ruffell and Batten, 1994).

Stewart (1978a) recognized four types of sand body atWorbarrow Bay; dominantly cross-bedded fining-upward units,irregularly organised units with flat-bedded lower portions,interleaved pebbly and medium-grained sandstones, and rarecoarsening-upward units. Here, the distinctive Coarse Quartz Gritis approximately 200 m above the base of the formation and

Fig. 45. Cliff sections within the lower Wessex Formation (Valanginian) at Mupe Bay, Dorset (Mupe Bay and Worbarrow Bay GCR site). The darker coloured Mupe Bay Oily

Boulder Bed makes up the higher part of the section. A boulder of oil-impregnated sandstone (dark grey) can be seen near the top of the section, approximately 1 m above the

folded map.


comprises tabular cross-bedded coarse sandstone enclosinglenticular pebble beds. Tourmalinised metasedimentary clastsare common and intercalated sands are rich in K-feldspar. Nowell(2000) recorded dewatering structures and a possible synsedi-mentary fault from the 70 m interval of strata below the grit. Leesand Cox (1937) recorded several further occurrences of oil-impregnated sand. Mansel-Pleydell (1888) noted dinosaur tracksand Iguanodon bones at unspecified levels. Recently, Ensom (2009)identified a tridactyl dinosaur footcast on a fallen block of WessexFormation sandstone within the bay.


Hughes and Croxton’s (1973) biostratigraphic scheme wasbased on distribution of Cicatricosisporites spores. This was laterconsidered erroneous by Hughes and McDougall (1990a), whoerected a new scheme utilizing angiospermid and other pollen. Theresults confirmed that the successions span the Valanginian–Barremian interval and indicated that the Coarse Quartz Grit(Fig. 46) broadly correlates with (a) the Hauterivian–Barremianboundary, (b) the Pine Raft horizon on the Isle of Wight (ComptonBay–Brighstone Bay site; Fig. 5) and (c) a depth of approximately430 m in the Warlingham borehole (Surrey, Weald Sub-basin;Worssam and Ivimey-Cook, 1971). Given the widespread recogni-tion of the Coarse Quartz Grit in Dorset and its probableisochroneity (Allen, 1989), Hughes and McDougall’s work allowedtentative recognition of this stage boundary throughout southern

England. Candidate correlative sand bodies in the Weald Sub-basinare seen in the Weald Clay Group at the Capel and Billingshurstsites. However, Robinson and Hesselbo’s (2004) composite fossil-wood carbon-isotope curve, incorporating data from WorbarrowBay, has allowed tentative correlation with a Tethyan carbonatecarbon-isotope curve. This suggests that the Coarse Quartz Grit isolder than the Pine Raft, perhaps mid-late Hauterivian. McMahonand Underhill (1995) proposed a Valanginian age for the CoarseQuartz Grit of Mupe Bay–Worbarrow Bay which they took to lieabove the correlative conformity of a major intra-Cretaceousunconformity, traceable westwards from Dorset into Devon. Wereject this interpretation on the basis of the chronostratigraphicevidence, notably Hughes and McDougall’s, presented above.

The obvious visual differences between the Upper Purbeck Bedsand Wessex Formation reflect significant Cornubian clastic influxin latest Berriasian and/or early Valanginian times, resulting inreplacement of lagoonal/lacustrine Purbeck environments by thealluvial Wealden regime (Fig. 9). This is attributed to markedupfaulting of the Cornubian source massif, increased precipitation,weathering of massif soils and enhanced runoff into the WessexSub-basin.

Stewart (1978a) noted the resemblance of the basal Wealdensand body at Mupe Bay to the Barnes High Sandstone (lower VectisFormation) of the Isle of Wight (Compton Bay–Brighstone Bay site),which possibly represents a progradational river mouth bar. Incontrast, Hesselbo and Allen (1991) proposed an inner lagoonal

Fig. 46. Pebbly sandstone (Coarse Quartz Grit) within the Wessex Formation (Valanginian possibly up to early Aptian) at Mupe Bay, Dorset (Mupe Bay and Worbarrow Bay

GCR site).


shoreline origin for the Mupe Bay sand and similar units below theOily Boulder Bed. Hesselbo and P.A. Allen interpreted associatedvaricoloured mudstones as overbank sediments, and the laminatedpurple-grey mudstones as lagoonal/lacustrine sediments. Theresulting vertical facies sequence was taken to indicate a regimethat fluctuated between lagoon, inner-lagoonal shoreline andfloodplain. It is likely that this model conceals a more complexpattern, influenced by both local and Cornubian tectonism (Allen,1981). Evidence for contemporaneous seismicity may come fromabundant soft sediment deformation at several levels beneath theOily Boulder Bed.

Hesselbo and Allen (1991) interpreted erosion surfaces beneaththe Oily Boulder Bed and a lower sand body as unconformities.Given resemblances of the resulting pattern to that of globaleustatic cycle charts, these surfaces were proposed as candidatesequence boundaries corresponding to Ryazanian–Valanginianeustatic sea-level fall. Hesselbo and Allen nevertheless acknowl-edged that the surfaces could alternatively be of local tectonicsignificance, or reflect changes in fluvial style (see below).

The Oily Boulder Bed (Fig. 45) marks the establishment ofalluvial conditions that persisted thereafter throughout theWealden. Miles et al. (1993) claimed that infiltration of oil intoboth the matrix and clasts/boulders was wholly post-Wealden. Incontrast, Kinghorn et al. (1994) favoured seepage during and afterthe Wealden. Gas chromatography–mass spectrometry analysis ofa rolled oil globule from the boulder bed (Wimbledon et al., 1996)complete with silty concentric laminae, confirms that oil within

the clasts was derived in Wealden times from Lias Group (LowerJurassic) strata preserved in the roots of a rollover anticline southof the Purbeck Fault. The Toarcian–Aalenian (late Lower Jurassic–early Middle Jurassic) Bridport Sands may have functioned as asubsurface reservoir at a slightly higher level within the structure,adjacent to a fault conduit opening to the surface (Selley andStoneley, 1987). This indicates a floodplain seep, close to thechannel in which the boulder bed accumulated as a lag deposit. Theclasts and boulders were derived through bank erosion andcollapse of oil-impregnated floodplain sediment (Wimbledonet al., 1996; Hesselbo, 1998). Jarosite skins on the clasts indicaterelatively high floodplain temperatures, and suggest alternatingdrought and stream flow. These conditions also account for thekaolinitic nature of the clasts, representing a weathering product of‘missing’ feldspar, abundant in the lag matrix. Live light oil in theboulder bed matrix suggests that oil is still escaping to the surface(Selley and Stoneley, 1987; Underhill and Stoneley, 1998).

The near-alignment of current directions in the Oily Boulder Bedwith the local tectonic dip suggests deposition on the northward-dipping limb of the rollover anticline, or a contemporaneous tectoniccontrol on channel development (Selley and Stoneley, 1987;Kinghorn et al., 1994; Wimbledon et al., 1996). Higher sedimentsat Mupe Bay and Worbarrow Bay were deposited by tectonicallyand/or climatically controlled interaction of braided and meander-ing streams (Allen, 1981, 1989), distal to the proximal–medialenvironments of Durdle Door. Beaconites burrows at Mupe Baysuggest marginal lacustrine or lacustrine-deltaic environments on at

Fig. 47. Vertical section through the Wessex Formation (Valanginian possibly up to early Aptian) at Worbarrow Bay, Dorset (Mupe Bay and Worbarrow Bay GCR site). After Stewart (1978a, p. 22).

J.D.

Ra

dley

, P

. A

llen /

Pro

ceedin

gs

of

the

Geo

log

ists’ A

ssocia

tion

12

3 (2

01

2)

31

9–

37

3

36

3

Fig. 48. Worbarrow Bay, Dorset (Mupe Bay and Worbarrow Bay GCR site). To the right, cliffs at the back of the bay expose steeply dipping sandstones and mudstones of the

Wessex Formation (Valanginian possibly up to early Aptian). Cliffs of Upper Cretaceous Chalk can be seen at top left. Photograph courtesy of Ian Harding, University of

Southampton.


least one occasion (Goldring and Pollard, 1995; Goldring et al., 2005).Colour-mottling of thicker floodplain muds indicates pedogenesisunder a warm to hot, periodically wet climate (Allen, 1998). TheCoarse Quartz Grit signifies high-energy braidplain deposition,possibly generated by uplift of Cornubia (Allen, 1989).

Nowell (1997) divided the Mupe Bay and Worbarrow succes-sions into five lithostratigraphic units, defined by criteria such asvertical distribution of ‘coarse quartz grit’ horizons and lignite(also see Nowell, 2000). Radley (1998) drew attention to evidencefor a main, widely distributed Coarse Quartz Grit and thewidespread distribution of lignite in the Lulworth area, weakeningNowell’s scheme. Nowell subsequently (1998a) reasserted theabsence of lignite in the Oily Boulder Bed to uphold the integrity ofhis unit W2. However it is again stressed that lignite occurs at thislevel, borne out by our field investigations (Wimbledon et al.,1996; Radley, 1998). These observations and independentmodelling (Stewart, 1978a; Wright et al., 2000; Sweetman andInsole, 2010) confirm that Wessex Formation plant debris beds arestrongly lenticular and unsuitable for correlation over more thanextremely short distances (e.g. Compton Bay–Brighstone Bay site).

10.5.4. Conclusions

These sections provide extensive exposures of the WessexFormation, demonstrating westerly attenuation and a range ofessentially fluvial environments in relative proximity to thePurbeck Fault and Cornubia. Investigations of palynology andfossil wood carbon-isotope stratigraphy have provided important

data, allowing tentative correlations with other sections insouthern England and possibly further afield. The basal beds atMupe Bay include unusual lacustrine/lagoonal–fluvial sedimentsand a complex oil-bearing unit, bearing on contemporaneousfaulting and regional structural development. These sites provide avital link in the Isle of Wight–Dorset chain of sites, which makepossible the investigation of the palaeogeographical, sedimento-logical and structural events of Early Cretaceous times. Thesections have considerable potential for further sedimentological,ichnological, geochemical, macropalaeontological and palynologi-cal studies.

10.6. Lulworth Cove, Dorset (SY 824798–SY 824797, SY 828798–

SY 828797)


The Wessex Formation is exposed on both sides of LulworthCove, east of the Durdle Door site, on the northern limb of thePurbeck Monocline (Fig. 2). It is visibly underlain by the well-bedded limestones and calcareous mudstones of the PurbeckGroup that form the ‘horns’ of the cove (Fig. 49). The highestWealden is apparently faulted out on the west side of the cove buta more complete succession capped by attenuated LowerGreensand is preserved on the east side (Fig. 50).

Wealden strata at Lulworth Cove were initially mentioned byWebster (1816), Conybeare and Phillips (1822), Fisher (1855) andDamon (1860). Most studies have concentrated on the better

Fig. 49. Cliff sections on the east side of the Lulworth Cove GCR site, Dorset. The steeply dipping sandstone and mudstone-dominated Wessex Formation (Valanginian possibly

up to early Aptian) occupies partly slumped and vegetated cliff sections on the left. Relatively well-bedded and resistant limestones and mudstones of the underlying Purbeck

Group (Berriasian) can be seen to the right.


exposed and less disturbed eastern sections (Fitton, 1836; Strahan,1898; Bates, 1898; Arkell, 1938, 1947). Groves (1931), Kirkaldy(1947), Allen (1975), Stewart (1978a), Allen (1989) and Sellwoodet al. (1991) investigated the sedimentology and geochemistry ofsome parts of the succession, and Ruffell and Batten (1994) carriedout preliminary palynological work. Goldring et al. (2005)documented the ichnofauna. Selley and Stoneley (1987), Nowell(1997, 1998a,b) and Radley (1998) discussed the possible influenceof synsedimentary faulting on sedimentation. The sections werementioned for example by Kirkaldy (1939), Butler (1998), Hawkeset al. (1998), Watson et al. (2001) and Radley (2002, 2006).

10.6.2. Description

Much of the succession dips steeply to the north and thelowest beds are locally slightly overturned. Approximately 175 mof strata are seen on the east side of the cove (Figs. 49 and 50) butthe faulted section to the west shows only about 60 m. Thesuccessions are dominated by sandy, occasionally varicolouredmudstones and medium to coarse-grained sands and sandstones,some ferruginous (Fig. 50). Thin ironstones occur, as well as thin,locally pyritic, lignitic beds. The junction with the underlyingUpper Purbeck Beds is not currently seen. The recorded sectionon the eastern side (Fig. 50 and below) commences probably afew metres above the Wealden base. Near the southernmost endof the section, boulders of trough cross-laminated sandstonederived from the lowest beds enclose bioturbated partingsrevealing thread-like burrows, possible bivalve ‘resting’ traces

(Lockeia) and disarticulated bivalves (‘Unio’ cf. subsinuatus). Leesand Cox (1937) identified oil sands at two levels, the lower ofwhich contains potassium-rich jarosite (Parker, 1972). Thesemay be the black sandy mudstones approximately 19 and 35 mabove the base of the exposed succession (Fig. 50). Detritalpetrography of the lower oil sand and other sand bodies (Groves,1931; Allen, 1975) reveals appreciable u-feldspar in the whole-rock analyses (up to 5%, some as quartz-schist), abundanttourmaline in the heavy fractions (up to 35%, with 8% fineaggregates) with some high-grade metamorphic elements(garnet, staurolite, total 3–4%) and notable proportions ofpink/reddish grains amongst the zircons (9%).

Fitton (1836) noted bivalves (Unio) and gastropods (‘Paludi-

na’ = Viviparus) approximately 30 m above the base. The CoarseQuartz Grit (faulted out on the west side) is developed as a series ofmultistorey lenticular pebbly sandstones, some fining upwardsand displaying planar cross-bedding. Its base lies about 65 mbelow the top of the Wealden (Fig. 50). Clast suites are dominatedby vein quartz, accompanied by tourmaliniferous metasediments,Carboniferous chert and occasional silicified Portlandian lime-stones (Kirkaldy, 1947; Sellwood et al., 1991). A thin sandstonewith Beaconites and possible Planolites burrows occurs approxi-mately 10 m below the grit.

Varicoloured mudstones within the higher strata displayreduction spots, some with carbonaceous cores. Ruffell and Batten(1994) recorded non-marine palynomorphs at unspecified levelson both sides of the cove. R.A. Coram (personal communication)

Fig. 50. Vertical section through the Wessex Formation (Valanginian possibly up to Aptian) on the east side of the Lulworth Cove GCR site, Dorset.


has noted a reptilian bone fragment near the top of the WessexFormation on the west side of the cove.


A broadly Valanginian up to Barremian or early Aptian age forthe Wessex Formation is indicated by late Berriasian UpperPurbeck Beds beneath, and the overlying Lower Greensand(Aptian). The abrupt replacement of highly fossiliferous UpperPurbeck mudstones and limestones by Wealden sands and

varicoloured mudstones (Fig. 49) reflects a widespread changefrom essentially lacustrine to alluvial environments. This isattributable largely to rapid upfaulting of the Cornubian massif(Fig. 9), resulting in greater rainfall and deeper weathering, andincreased runoff into the Wessex Sub-basin (Allen, 1981, 1998).

The sands have predominantly Cornubian (Hercynian) compo-sitions. Scarce Upper Jurassic debris could have come from rocksflanking the massif on the west (Fig. 9), and/or from the nearbynorthern basin margin (Fig. 4). Potassium-rich jarosite in the lower

Fig. 51. Man-o’-War Cove, Durdle promontory, Dorset (Durdle Door GCR site). Pale sands and mudstones of the Wessex Formation (Valanginian possibly up to early Aptian)

outcrop to the right of the gully marked by a footpath. To the left are near-vertical, well-bedded limestones and mudstones of the underlying Purbeck Group (Berriasian). The

Isle of Portland is visible in the distance, capped by gently dipping Portland Stone and basal Purbeck strata (Portlandian–Berriasian).


oil sand may be a contemporaneous weathering product offeldspar but the latter is not significantly scarcer than the averagefor the district. Coarser sands are probably channel deposits, whilevaricoloured mudstones reflect pedogenesis of interchannelfloodplain muds under a warm to hot, periodically wet climate.The sparse trace fossils and freshwater molluscs hint at low-energychannels or overbank water bodies. In contrast, the Coarse QuartzGrit comprises a series of channel fills (Sellwood et al., 1991) in abraidplain setting subject to powerful floods. Renewed uplift of theCornubian massif and increased storm frequency are likely causes.

Nowell (1997) provided evidence for several north-west/south-east trending pre-Albian faults in the Lulworth area and dividedthe Wessex Formation into several lithostratigraphic units. Bydocumenting lateral changes in the thicknesses of these units heenvisaged infra-Wealden movement on a fault running throughthe mouth of Lulworth Cove. However, as seen, the lithology of thelocal Wealden is highly variable laterally and vertically, andNowell’s subdivisions are difficult to recognize in the field.Nevertheless, growth faults were active in the sub-basin andmust have had some bearing on sedimentation, including thegeneration of oil seeps (Selley and Stoneley, 1987; Wimbledonet al., 1996). Butler (1998) suggested that the Lulworth successionmight have been deposited on a basin margin fault block, given itslocation within the south Dorset zone of structural disturbance.

10.6.4. Conclusions

The exposures supplement those at Mupe Bay and WorbarrowBay in demonstrating relationships with the underlying Purbeck

Group, and the increasingly coarse-grained and attenuated natureof the Wessex Formation towards the former Cornubian uplands.Further investigation will undoubtedly enhance our understandingin the region, and will facilitate comparison with nearby coastalsections (e.g. Durdle Door and Mupe Bay–Worbarrow Bay sites)and further afield. This is a key site for elucidating thesedimentological and structural evolution of the south Dorsetregion during the Early Cretaceous.

10.7. Durdle Door, Dorset (SY 805802–807802)


Cliff exposures on both sides of the Durdle promontory, 2 kmwest of Lulworth Cove (Fig. 2) provide spectacular sections of theWessex Formation on the northern limb of the Purbeck Monocline(Fig. 51). The Wealden strata are faulted against late BerriasianUpper Purbeck Beds to the south, and overlain unconformably byAlbian Gault Clay to the north. The well-known landmark of DurdleDoor lies at the seaward edge of the promontory and is a naturalarch in steeply dipping Portland Stone and Lower Purbeck strata.

The sections were mentioned for example by Webster (1816),Conybeare and Phillips (1822), Bates (1898), Kirkaldy (1939) andHawkes et al. (1998), and the Wealden succession has beenoutlined by Fitton (1824, 1836) and Arkell (1938, 1947). Especiallynoteworthy is the thick Coarse Quartz Grit, the petrography ofwhich has been researched extensively by Kirkaldy (1947), Oakley(1947), Allen (1972, 1975, 1981, 1989) and Garden (1991). Oakley’srecords of reworked microfossils were reviewed by Haslett (1996)


and Radley (2005). 40Ar/39Ar whole-rock dating of sandand pebble-grade detritus was undertaken by Fitch and Miller(1972). Ruffell and Batten (1994) carried out some preliminarypalynological sampling. Plant macrofossils were noted byCope (1971).

10.7.2. Description

The succession is slightly overturned and approximately 65 mthick on the east side of the promontory (Man-o’-War Cove;Fig. 51). It comprises coarse, frequently pebbly sands, lignites, andvaricoloured mudstones. The highest Upper Purbeck strata andapproximately the lowest 39 m of the Wessex Formation are cutout on both sides of the promontory by a southward-dipping thrustfault. Arkell (1938, 1947) estimated that the highest 90 m of theWessex Formation have been removed by pre-Albian erosion.Further faulting accounts for the thinner succession (c. 48 m) andabsence of the Coarse Quartz Grit on the west side of thepromontory. The following section at Man-o’-War Cove is adaptedfrom Arkell (1947).

Sands and mudstones with lignite..11.7 m

Coarse Quartz Grit..8.4 m

Varicoloured mudstones and white sand..18.3 m

White sandstone..3 m

Varicoloured mudstones with an indefinite lignitic quartz gritat 17.4 m - 19.2 m below the top..23.1 m

(fault breccia below)

Grey mudstones in the lower part of the succession containlarge lignite fragments. Finer lignitic debris occurs in the overlyingsands which are laminated and cross-bedded. Cope (1971)recorded well-preserved bennettitalean fronds (possibly Ptero-

phyllum) in a bed of buff coloured siltstone. Ruffell and Batten(1994) recovered non-marine palynomorphs from an unspecifiedlevel.

The Coarse Quartz Grit (Fig. 5) comprises pebbly and locallycross-bedded coarse sands, interbedded with finer-grained wavy-bedded and laminated sands containing lignite fragments (somefusainized). Overall the clasts are poorly sorted and the sandgrains highly angular. The pebble grade is rich in quartz andtourmaliniferous metasediments and includes Carboniferouscherts (some containing radiolarians; Oakley, 1947), silicifiedvolcanic rocks (Garden, 1991), pink silicified dolomite and barite-bearing rocks. Jurassic debris appears to be absent (e.g. neitherglauconite nor phosphorite has been found), but occurs at nearbylocalities (Garden, 1991). Feldspar is noteworthily missing fromthe sand grade, the heavy fractions of which are dominated bytourmaline (87%, including 24% of fine aggregates). Topaz (0.4%)and andalusite are significant source-wise. Possible lateriticmaterial (?diaspore) in the clay fraction has been reported (Allen,1972).


An overall Valanginian up to Barremian or early Aptian age isindicated by the presence of late Berriasian Upper Purbeck Bedsbelow (Fig. 51) and comparison with the Lulworth Cove and MupeBay–Worbarrow Bay sites to the east, which are overlain by AptianLower Greensand. These are the westernmost coastal exposures ofWealden strata within the Wessex Sub-basin and reveal unusuallycoarse-grained facies. This indicates deposition in an alluvial plainsubject to phases (possibly storm driven) of stream braiding. TheCornubian massif cannot have been more than 80–90 km distant to

the west (Allen, 1981; Fig. 9). The ultimate source of much of thisdebris was an ancient Armorican metamorphic complex withminor igneous intrusions (Allen, 1972, 1975). 40Ar/39Ar whole-rockdating by Fitch and Miller (1972) suggests that the complex wasaffected by at least three episodes of tourmalinization during thelate Precambrian–Lower Carboniferous interval (Allen, 1972). Thepink silicified barite rocks and dolomites may be evidence ofvolcanic metasomatism on Cornubia at some time up to theWealden. Lower Cretaceous volcanism on the massif is indeedindicated by the Wolf Rock and Epson Shoal phonolites, latemineralization, and volcanic rocks in the SouthwesternApproaches (Allen, 1981). McMahon and Turner (1998) took thesefeatures to suggest a thermal mechanism for Cornubian uplift.

The Coarse Quartz Grit is at its thickest here, suggestingproximity to a fan apex sourced from an embayment in the easternmargin of Cornubia (Allen, 1981; Fig. 9). The deposit could reflectmajor rainstorms which flooded the whole Wessex Sub-basin andbeyond. Lateritic detritus, if confirmed, would imply derivationfrom massif soils generated under a warm, periodically arid(Mediterranean) climate (Allen, 1998). The abundant ligniterepresents intrabasinal and extrabasinal debris and includeswildfire products.

Eastwards, the sediments presumably grade laterally intothe thicker, and on the whole finer lithofacies at LulworthCove, Mupe Bay–Worbarrow Bay, Swanage and the Isle of Wight.They could however, represent the feather edge of coarse basaldeposits left by post-Wealden erosion. The two scenarios,including the possible roles of growth faulting, are still underdebate. Although relatively incomplete, the succession providesa picture of high-energy alluvial environments in the westernpart of the Wessex Sub-basin, sourced from the eastern margin ofthe Cornubian massif (Fig. 9) and fed by seasonal (sometimestorrential) streams.

10.7.4. Conclusions

The site is outstandingly important for future research on localand regional problems of Wealden sedimentology, palaeobotany,palaeoenvironments and palaeogeography posed by the WessexFormation.

10.8. Upwey/Bincombe, Dorset (SY 672854)


Railway cuttings at Ridgeway, north of Weymouth, provide thewesternmost exposures of Wealden strata (Wessex Formation) insouthern England. Mantell (1848a), Weston (1848, 1852), Fisher(1855) and Damon (1860) noted animal and plant fossils here. Thesections are now largely obscured, but were described by Strahan(1898). They were additionally mentioned by Blake and Hudleston(1879).

10.8.2. Description

The succession is approximately 105 m thick, dips at 40–508 tothe north and is dominated by sands and varicoloured mottledmudstones. Southwards it is underlain by the Purbeck Group andfaulted against Oxfordian (Upper Jurassic) Oxford Clay on thenorth. It is generally considered to be Valanginian–Barremian inage. The quartz gravel bed noted by Strahan (1898) may representthe well-known Coarse Quartz Grit. Dinosaur bones (attributableto Iguanodon, ‘Hylaeosaurus’ and ‘Megalosaurus’) and land plants(Clathraria; a cycadeoid) occur near the Wealden base (Mantell,1848a; Damon, 1860), and unionoid bivalves were found inconglomeratic bands at unspecified levels (Weston, 1848; Fisher,1855). Preliminary petrographic investigation of the sands hasrevealed abundant grains of K-feldspar, Hercynian tourmaline andtourmaline fine aggregates. Associated mudstones, predominantly


mixtures of illite and illite–smectite (mixed layer) minerals, haveappreciable kaolinite contents.


The quartz gravel bed is thought to have formed part of a high-energy braidplain extending eastwards from Cornubia, possiblyacross the whole sub-basin. The sands presumably occupiedchannel and overbank environments. The varicoloured mudstonessignify pedogenesis under a warm humid climate generatingfluctuations, possibly seasonal, in groundwater levels.

10.8.4. Conclusions

The site is potentially important for elucidating Wealdenpalaeoenvironments and stratigraphy. Records of animal and plantfossils indicate its value for elucidating the biostratigraphy,palaeoecology and biology of both the lowlands and nearbyuplands.

Acknowledgements

Amongst the many who assisted with our work in the WessexSub-basin, we especially thank Neil Ellis (Joint Nature Conserva-tion Committee, Peterborough), Bill Wimbledon (formerly Coun-tryside Council for Wales), Roland Goldring (1928–2005; formerlyUniversity of Reading), Robert Coram (British Fossils), David Battenand Joan Watson (University of Manchester), David Martill andSteve Sweetman (University of Portsmouth), Mike Barker (former-ly University of Portsmouth), Trevor Price and Steve Hutt (DinosaurIsle), Martin Munt (Natural History Museum, London), Phil Palmerand Paul Ensom (formerly of the Natural History Museum,London), Ian Harding (University of Southampton), Jane Francis(University of Leeds), Susan Evans (University College, London),Alastair Ruffell (Queen’s University, Belfast), Stephen Hesselbo(University of Oxford), Richard Edmonds (Dorset County Council)and Michael Green (Isle of Wight). Sincere gratitude is expressed toJim Rose for his patience, advice and editorial expertise, to JennyKynaston for her technical drawing skills and to Lisa Gordon(Elsevier) for her assistance. Jon Radley would like to express hisprofound thanks to Perce Allen’s children, Ruth, John, Jim andHenry Allen, for their patience, assistance and enthusiasm for thisproject. The generous assistance of The Curry Fund of theGeologists’ Association is acknowledged, for the production ofillustrations.

References

Ainsworth, N.R., Braham, W., Gregory, F.J., Johnson, B., King, C., 1998. The lithos-tratigraphy of the latest Triassic to earliest Cretaceous of the English Channeland its adjacent areas. In: Underhill, J.R. (Ed.), Development, Evolution and

Petroleum Geology of the Wessex Basin, Geological Society, London, pp. 103–164, Special Publication 133.

Allen, P., 1972. Wealden detrital tourmaline: implications for northwestern Europe.Journal of the Geological Society, London 128, 273–294.

Allen, P., 1975. Wealden of the Weald: a new model. Proceedings of the Geologists’Association 86, 389–437.

Allen, P., 1981. Pursuit of Wealden models. Journal of the Geological Society, London138, 375–405.

Allen, P., 1989. Wealden research—ways ahead. Proceedings of the Geologists’Association 100, 529–564.

Allen, P., 1991. Provenance research: Torridonian and Wealden. In: Morton, A.C.,Haughton, P.D.W. (Eds.), Developments in Sedimentary Provenance Studies.Geological Society, Special Publication 57, pp. 13–21.

Allen, P., 1998. Purbeck–Wealden (early Cretaceous) climates. Proceedings of theGeologists’ Association 109, 197–236.

Allen, P., Keith, M.L., 1965. Carbon isotope ratios and palaeosalinities of Purbeck–Wealden carbonates. Nature 208, 1278–1280.

Allen, P., Keith, M.L., Tan, F.C., Deines, P., 1973. Isotopic ratios and Wealdenenvironments. Palaeontology 16, 607–621.

Allen, P., Wimbledon, W.A., 1991. Correlation of NW European Purbeck–Wealden(nonmarine Lower Cretaceous) as seen from the English type-areas. CretaceousResearch 12, 511–526.

Alvin, K.L., 1974. Leaf anatomy of Weichselia based on fusainized material. Palaeon-tology 17, 587–598.

Alvin, K.L., Muir, M.D., 1970. An epiphyllous fungus from the Lower Cretaceous.Biological Journal of the Linnean Society 2, 55–59.

Alvin, K.L., Spicer, R.A., Watson, J., 1978. A Classopollis-containing male coneassociated with Pseudofrenelopsis. Palaeontology 21, 847–856.

Alvin, K.L., Fraser, C.J., Spicer, R.A., 1981. Anatomy and palaeoecology of Pseudo-frenelopsis and associated conifers in the English Wealden. Palaeontology 24,759–778.

Alvin, K.L., Watson, J., Spicer, R.A., 1994. A new coniferous male cone from theEnglish Wealden and a discussion of pollination in the Cheirolepidiaecae.Palaeontology 37, 173–180.

Anderson, F.W., 1966. New genera of Purbeck and Wealden Ostracoda. Bulletin ofthe British Museum, Natural History (Geology) 11, 435–446.

Anderson, F.W., 1967. Ostracods from the Weald Clay of England. Bulletin of theGeological Survey of Great Britain 27, 237–269.

Anderson, F.W., 1985. Ostracod faunas in the Purbeck and Wealden of England.Journal of Micropalaeontology 4, 1–68.

Anderson, F.W., Bazley, R.A.B., 1971. The Purbeck Beds of the Weald (England).Bulletin of the Geological Survey of Great Britain 34, 1–173.

Anderson, F.W., Bazley, R.A.B., Shephard-Thorn, E.R., 1967. The sedimentary andfaunal sequence of the Wadhurst Clay (Wealden) in boreholes at WadhurstPark, Sussex. Bulletin of the Geological Survey of Great Britain 27, 171–235.

Arkell, W.J., 1934. Whitsun field meeting 1934. The Isle of Purbeck. Proceedings ofthe Geologists’ Association 45, 412–419.

Arkell, W.J., 1938. Three tectonic problems of the Lulworth district: studies on themiddle limb of the Purbeck fold. Quarterly Journal of the Geological Society,London 94, 1–54.

Arkell, W.J., 1947. The geology of the country around Weymouth, Swanage, Corfeand Lulworth. Memoir of the Geological Survey of Great Britain. HMSO, London,xxvii + 386 pp.

Barker, M.J., Clarke, J.B., Martill, D.M., 1997a. Mesozoic reptile bones as diageneticwindows. Bulletin de la Societe Geologique de France 168, 535–545.

Barker, M.J., Munt, M.C., Radley, J.D., 1997b. The first recorded trigonioidoideanbivalve from Europe. Palaeontology 40, 955–963.

Barnard, T., 1948. Whitsun field meeting to the Isle of Wight. Proceedings of theGeologists’ Association 59, 229–233.

Bates, J.I., 1898. The geology of Swanage and neighbouring district. Proceedings ofthe Warwickshire Naturalists’ and Archaeologists’ Field Club, 43rd AnnualReport 14–32.

Batten, D.J., 1974. Wealden palaeoecology from the distribution of plant fossils.Proceedings of the Geologists’ Association 85, 433–458.

Batten, D.J., 1982. Palynofacies and salinity in the Purbeck and Wealden of southernEngland. In: Banner, F.T., Lord, A.R. (Eds.), Aspects of Micropalaeontology.George Allen and Unwin, London, pp. 278–308.

Batten, D.J., 1996a. Chapter 7C. Colonial chloroccoccales. In: Jansonius, J., McGregor,D.C. (Eds.), Palynology: Principles and Applications, vol. 1. American Associa-tion of Stratigraphic Palynologists Foundation, pp. 191–203.

Batten, D.J., 1996b. Chapter 20E. Upper Jurassic and Cretaceous miospores. In:Jansonius, J., McGregor, D.C. (Eds.), Palynology: Principles and Applications,vol. 2. American Association of Stratigraphic Palynologists Foundation, pp. 807–830.

Batten, D.J., 1996c. Chapter 26A. Palynofacies and palaeoenvironmental interpre-tation. In: Jansonius, J., McGregor, D.C. (Eds.), Palynology: Principles andApplications, vol. 3. American Association of Stratigraphic Palynologists Foun-dation, pp. 1011–1064.

Batten, D.J., 2002. Palaeoenvironmental setting of the Purbeck Limestone Group ofDorset, southern England. In: Milner, A.R., Batten, D.J. (Eds.), Life and Environ-ments in Purbeck Times. Special Papers in Palaeontology 68, 13–20.

Batten, D.J. (Ed.), 2011. English Wealden fossils. Palaeontological AssociationField Guides to Fossils Series, No. 14. Palaeontological Association, London, p.769.

Batten, D.J., Lister, J.K., 1988a. Evidence of freshwater dinoflagellates and other algaein the English Wealden (Early Cretaceous). Cretaceous Research 9, 171–179.


Batten, D.J., Lister, J.K., 1988b. Early Cretaceous dinoflagellate cysts and chlorococ-calean algae from freshwater and low salinity palynofacies in the EnglishWealden. Cretaceous Research 9, 337–367.

Beckles, S.H., 1851. On supposed casts of footprints in the Wealden. QuarterlyJournal of the Geological Society, London 7, 117.

Beckles, S.H., 1852. On the Ornithoidichnites in the Wealden. Quarterly Journal ofthe Geological Society, London 8, 396–397.

Beckles, S.H., 1862. On some natural casts of reptilian footprints in the WealdenBeds of the Isle of Wight and of Swanage. Quarterly Journal of the GeologicalSociety, London 18, 443–447.

Benton, M.J., Spencer, P.S., 1995. Fossil Reptiles of Great Britain, Geological Conser-vation Review Series, No. 10. Chapman and Hall, London, xii + 386 pp.

Bigge, M.A., Farrimond, P., 1998. Biodegradation of oils in the Wessex Basin: acomplication of correlation. In: Underhill, J.R. (Ed.), Development, Evolutionand Petroleum Geology of the Wessex Basin, Geological Society, London, pp.373–388, Special Publication 133.

Blake, J.F., Hudleston, W.H., 1879. Excursion to Weymouth and Portland. Proceed-ings of the Geologists’ Association 6, 172.

Bown, P.R., Cooper, M.K.E., 1998. Jurassic. In: Bown, P.R. (Ed.), Calcareous Nanno-fossil Biostratigraphy. Chapman & Hall, pp. 34–85.

Bray, P.S., Anderson, K.B., 2008. The nature and fate of natural resins in the geo-sphere XIII: a probable pinaceous resin from the early Cretaceous (Barremian),Isle of Wight. Geochemical Transactions 9, 3, doi:10.1186/1467-4866-9-3.

Bristow, H.W., 1862. The geology of the Isle of Wight. Memoirs of the GeologicalSurvey of Great Britain and of the Museum of Practical Geology. HMSO, London,xix + 138 pp.

British Geological Survey, 2000. Swanage England and Wales Sheets 342 (east) and343. Solid and Drift Geology. 1:50,000. British Geological Survey, Keyworth,Nottingham.

Buckland, W.H., De la Beche, H.T., 1836. On the geology of Weymouth and theadjacent parts of the coast of Dorset. Transactions of the Geological Society ofLondon Series 2 (4), 1–46.

Butler, M., 1998. The geological history of the southern Wessex Basin—a review ofnew information from oil exploration. In: Underhill, J.R. (Ed.), Development,Evolution and Petroleum Geology of the Wessex Basin, Geological Society,London, pp. 67–86, Special Publication 133.

Callomon, J.H., Cope, J.C.W., 1995. The Jurassic geology of Dorset. In: Taylor, P.D.(Ed.), Field Geology of the British Jurassic. Geological Society, London, pp. 51–103.

Carruthers, W., 1870. On fossil cycadean stems from the Secondary rocks of Britain.Transactions of the Linnean Society of London 4, 675–708.

Casey, R., 1955. The pelecypod family Corbiculidae in the Mesozoic of Europe andthe Near East. Journal of the Washington Academy of Sciences 45, 366–372.

Casey, R., 1961. The stratigraphical palaeontology of the Lower Greensand. Palaeon-tology 3, 487–621.

Chadwick, R.A., 1986. Extension tectonics in the Wessex Basin southern England.Journal of the Geological Society, London 143, 465–488.

Clarke, J.B., 1991. Diagenetic and compactional history of an Iguanodon vertebrafrom the Vectis Formation of the Isle of Wight. Proceedings of the Isle of WightNatural History and Archaeological Society 10, 149–158.

Clarke, J.B., 2004. A mineralogical method to determine cyclicity in the taphonomicand diagenetic history of fossilized bones. Lethaia 37, 281–284.

Clarke, J.B., Barker, M.J., 1993. Diagenesis in Iguanodon bones from the WealdenGroup, Isle of Wight, southern England. Kaupia: Darmstadter Beitrage zurNaturgeschichte 2, 57–65.

Cleevely, R.J., Morris, N.J., 1988. Taxonomy and ecology of Cretaceous Cassiopidae(Mesogastropoda). Bulletin of the British Museum (Natural History) Geology 44,233–291.

Colenutt, G.W., Hooley, R.W., 1906. Excursion to the Isle of Wight, Whitsuntide,1906. Proceedings of the Geologists’ Association 19, 357–366.

Colenutt, G.W., Hooley, R.W., 1919. Excursion to the Isle of Wight. Proceedings ofthe Geologists’ Association 30, 133–138.

Collinson, M.E., Featherstone, C., Cripps, J.A., Nichols, G.J., Scott, A.C., 2000. Charcoal-rich plant debris accumulations in the Lower Cretaceous of the Isle of Wight,England. Acta Palaeobotanica Supplement 2, 93–105.

Conybeare, W.D., Phillips, W., 1822. Outlines of the Geology of England and Wales.William Phillips, London, lxi + 470 pp.

Cope, J.C.W., 1971. Plant remains from the Wealden Beds. Proceedings of the DorsetNatural History and Archaeological Society 92, 42.

Daley, B., Insole, A., 1984. The Isle of Wight. Geologists’ Association Guide No. 25, 34pp..

Daley, B., Stewart, D.J., 1979. Week-end Field Meeting: the Wealden Group in theIsle of Wight. Proceedings of the Geologists’ Association 90, 51–54.

Damon, R., 1860. Handbook to the Geology of Weymouth and the Isle of Portland.Edward Stanford, London, xii + 199 pp.

Delair, J.B., 1983. Cretaceous dinosaur footprints from the Isle of Wight: a briefhistory. Proceedings of the Isle of Wight Natural History and ArchaeologicalSociety 7, 609–615.

Delair, J.B., 1989. A history of dinosaur footprint discoveries in the British Wealden.In: Gillette, D.D., Lockley, M.G. (Eds.), Dinosaur Tracks and Traces. CambridgeUniversity Press, pp. 19–25.

Delvene, G., Araujo, R., 2009. Early Cretaceous non-marine bivalves from theCameros and Basque–Cantabrian basins of Spain. Journal of Iberian Geology35, 19–34.

Delvene, G., Munt, M., 2011. New Trigonioidoidea (Bivalvia; Unionoida) from theEarly Cretaceous of Spain. Palaeontology 54, 631–638.

Dineley, D.L., Metcalf, S.J., 1999. The Fossil Fishes of Great Britain. GeologicalConservation Review Series, No. 16. Joint Nature Conservation Committee,Peterborough, xxi + 675 pp.

Ensom, P.C., 2009. A dinosaur track from the Wealden Group (Lower Cretaceous),Worbarrow Bay, Dorset, southern England. Proceedings of the Dorset NaturalHistory and Archaeological Society 130, 233–234.

Evans, S.E., Barrett, P.M., Ward, D.J., 2004. The first record of lizards and amphibiansfrom the Wessex Formation (Lower Cretaceous: Barremian) of the Isle of Wight,England. Proceedings of the Geologists’ Association 115, 239–247.

Falcon, F.L., Kent, P.E., 1960. Geological results of petroleum exploration in Britain,1945–57. Geological Society Memoir, 2, 56 pp.

Feist, M., Lake, R.D., Wood, C.J., 1995. Charophyte biostratigraphy of the Purbeck andWealden of southern England. Palaeontology 38, 407–442.

Fisher, O., 1855. On the Purbeck strata of Dorsetshire. Transactions of the CambridgePhilosophical Society 9, 555–581.

Fitch, F.J., Miller, J.A., 1972. 40Ar/39Ar dating of detrital tourmaline and tourmali-nized rocks; schists and micas. Journal of the Geological Society, London 128,291–294.

Fitton, W.H., 1824. Inquiries respecting the geological relations of the beds betweenthe Chalk and the Purbeck Limestone in the south east of England. Annals ofPhilosophy 8, 365–383.

Fitton, W.H., 1836. Observations on some of the strata between the Chalk and theOxford Oolite in the Southeast of England. Transactions of the GeologicalSociety of London Second Series 4, 103–390.

Fitton, W.H., 1847. A stratigraphical account of the section from Atherfield toRocken End on the south-west coast of the Isle of Wight. Quarterly Journalof the Geological Society, London 3, 289–328.

Francis, J.E., 1987. The palaeoclimatic significance of growth rings in late Jurassic/early Cretaceous fossil wood from southern England. In: Ward, R.G.W. (Ed.),BARInternational Series 333. pp. 21–36.

Francis, J.E., Harland, B.M., 2006. Termite borings in Early Cretaceous fossil wood,Isle of Wight, UK. Cretaceous Research 27, 773–777.

Freeman, E.F., 1975. The isolation and ecological implications of the microverte-brate fauna of a Lower Cretaceous lignite bed. Palaeontology 86, 307–312.

Gale, A.S., 2000. Early Cretaceous: rifting and sedimentation before the flood. In:Woodcock, N., Strachan, R. (Eds.), Geological History of Britain and Ireland.Blackwell Science, pp. 339–355.

Garden, I.R., 1991. Changes in the provenance of pebbly detritus in southern Britainand northern France associated with basin rifting. In: Morton, A.C., Haughton,P.D.W. (Eds.), Developments in Sedimentary Provenance Studies, GeologicalSociety, London, pp. 273–289, Special Publication 57.

Godwin-Austen, R.A.C., 1872. Address by Robert A.C. Godwin-Austen, President ofthe section. Report of the forty-second meeting of the British Association for theAdvancement of Science, Notices and Abstracts of miscellaneous communica-tions to the sections, 90–96.

Goldring, R., Pollard, J.E., 1995. A re-evaluation of Ophiomorpha burrows in theWealden Group (Lower Cretaceous) of southern England. Cretaceous Research16, 665–680.

Goldring, R., Pollard, J.E., Radley, J.D., 2005. Trace fossils and pseudofossils from theWealden strata (nonmarine Lower Cretaceous) of southern England. CretaceousResearch 26, 665–685.

Grocke, D.R., Hesselbo, S.P., Jenkyns, H.C., 1999. Carbon-isotope composition ofLower Cretaceous fossil wood: ocean-atmosphere chemistry and relation tosea-level change. Geology 27, 155–158.

Groves, A.W., 1931. The unroofing of the Dartmoor Granite and the distribution ofits detritus in the sediments of southern England. Quarterly Journal of theGeological Society, London 87, 62–96.

Hall, S., 1933. Field meeting in the Isle of Wight. Proceedings of the Geologists’Association 44, 84–186.

Hallam, A., Grose, J.A., Ruffell, A.H., 1991. Palaeoclimatic significance of changes inclay mineralogy across the Jurassic–Cretaceous boundary in England andFrance. Palaeogeography, Palaeoclimatology, Palaeoecology 81, 173–187.

Hamblin, R.J.O., Crosby, A., Balson, P.S., Jones, S.M., Chadwick, R.A., Penn, I.E., Arthur,M.J., 1992. The geology of the English Channel. British Geological Survey, UnitedKingdom Offshore Regional Report. HMSO, London, 106 pp.

Harding, I.C., 1988. A remarkable new early Cretaxeous trilete spore: with observa-tions on sporoderm function and stratigraphic significance. Review of Palaeo-botany and Palynology 54, 165–173.

Harding, I.C., Allen, R.M., 1995. Dinocysts and the palaeoenvironmental interpreta-tion of non-marine sediments: an example from the Wealden of the Isle ofWight (Lower Cretaceous, southern England). Cretaceous Research 16, 727–743.

Harris, T.M., 1981. Burnt ferns from the English Wealden. Proceedings of theGeologists’ Association 92, 47–58.

Hart, M.B., Weaver, P.P.E., Clements, R.G., Burnett, J.A., Tocher, B.A., Batten, D.J.,Lister, J.K., MacLennan, A.M., 1987. Cretaceous. In: Lord, A.R., Bown, P.R.(Eds.), Mesozoic and Cenozoic Stratigraphical Micropalaeontology of theDorset Coast and Isle of Wight. British Micropalaeontological Society GuideBook 1, pp. 88–149.

Haslett, S.K., 1996. Annotated bibliography of fossil radiolaria occurrences in theBritish Isles. Proceedings of the Geologists’ Association 107, 281–286.

Hawkes, P.W., Fraser, A.J., Einchcomb, C.C.G., 1998. The tectono-stratigraphicdevelopment and exploration history of the Weald and Wessex basins, South-ern England, UK. In: Underhill, J.K. (Ed.), Development, Evolution and PetroleumGeology of the Wessex Basin. Geological Society, London, Special Publication133, pp. 39–65.

http://dx.doi.org/10.1186/1467-4866-9-3


Haworth, M., Hesselbo, S.P., McElwain, J.C., Robinson, S.A., Brunt, J.W., 2005. MidCretaceous pCO2 based on stomata of the extinct conifer Pseudofrenelopsis(Cheirolepidiaceae). Geology 33, 749–752.

Haworth, M., McElwain, J., 2008. Hot, dry, wet, cold or toxic? Revisiting theecological significance of leaf and cuticular micromorphology. Palaeogeogra-phy, Palaeoclimatology, Palaeoecology 262, 79–90.

Haywood, A.M., Valdes, P.J., Markwick, P.J., 2004. Cretaceous (Wealden) climates: amodeling perspective. Cretaceous Research 25, 303–311.

Heads, S.W., 2006. A new caddisfly larval case (Insecta, Trichoptera) from theLower Cretaceous Vectis Formation (Wealden Group) of the Isle of Wight,southern England. Proceedings of the Geologists’ Association 117, 307–310.

Herries, R.S., 1910. The Isle of Wight. In: Monckton, H.W., Herries, R.S. (Eds.),Geology In The Field: The Jubilee Volume of the Geologists’ Association(1858–1908). Edward Stanford, London, pp. 414–432.

Hesselbo, S.P., 1998. Basal Wealden of Mupe Bay: a new model. In: Underhill, J.K.(Ed.), Development, Evolution and Petroleum Geology of the Wessex Basin,Geological Society, London, pp. 349–353, Special Publication 133.

Hesselbo, S.P., Allen, P.A., 1991. Major erosion surfaces in the basal Wealden bedsLower Cretaceous, south Dorset. Journal of the Geological Society, London 148,105–113.

Holmes, T.V., Leighton, T., 1892. Excursion to the Isle of Wight. Proceedings of theGeologists’ Association 12, 145–172.

Horne, D.J., 1995. A revised ostracod biostratigraphy for the Purbeck–Wealden ofEngland. Cretaceous Research 16, 639–663.

Horne, D.J., Martens, K., 1998. An assessment of the importance of resting eggs forthe evolutionary success of Mesozoic non-marine cypridoidean Ostracoda(Crustacea). Archiv fur Hydrobiologie Special Issues Advanced Limnology 52,549–561.

House, M.R., 1961. The structure of the Weymouth anticline. Proceedings of theGeologists’ Association 72, 221–238.

House, M.R., 1993. Geology of the Dorset coast, Second edition. Geologists’ Associa-tion Guide No. 22. , 164 pp.

Howse, S.C.B., Milner, A.R., Martill, D.M., 2001. Pterosaurs. In: Martill, D.M., Naish, D.(Eds.), Dinosaurs of the Isle of Wight. Palaeontological Association Field Guideto Fossils 10. Palaeontological Association, London, pp. 324–355.

Hudleston, W.H., 1882. Excursion to the Isle of Purbeck. Proceedings of the Geol-ogists’ Association 7, 377–390.

Hudleston, W.H., Morris, J., 1882. Excursion to the Isle of Purbeck. Proceedings of theGeologists’ Association 7, 377–390.

Hughes, N.F., 1958. Palaeontological evidence for the age of the English Wealden.Geological Magazine 95, 41–49.

Hughes, N.F., 1975. Plant succession in the English Wealden strata. Proceedings ofthe Geologists’ Association 86, 439–455.

Hughes, N.F., 1994. The enigma of angiosperm origins. Cambridge University Press,xiii + 317 pp.

Hughes, N.F., Croxton, C.A., 1973. Palynologic correlation of the Dorset ‘Wealden’.Palaeontology 16, 66–77.

Hughes, N.F., Drewry, G.E., Laing, J.F., 1979. Barremian earliest angiosperm pollen.Palaeontology 22, 513–535.

Hughes, N.F., McDougall, A.B., 1990a. New Wealden correlation for the WessexBasin. Proceedings of the Geologists’ Association 101, 85–90.

Hughes, N.F., McDougall, A.B., 1990b. Barremian–Aptian angiospermid pollenrecords from southern England. Review of Palaeobotany and Palynology 65,145–151.

Insole, A.N., Hutt, S., 1994. The palaeoecology of the dinosaurs of the WessexFormation (Wealden Group, Early Cretaceous), Isle of Wight, Southern England.Zoological Journal of the Linnean Society 112, 197–215.

Insole, A., Daley, B., Gale, A., 1998. The Isle of Wight. Geologists’ Association GuideNo. 60, 132 pp.

Jackson, J.F., 1930. A catalogue of Cretaceous fossils in the Museum of Isle of WightGeology, the Free Library, Sandown. Proceedings of the Isle of Wight NaturalHistory and Archaeological Society 2, 45–61.

Jackson, J.F., 1933. A supplementary list of fossils in the Museum of Isle of WightGeology, the Free Library, Sandown. Proceedings of the Isle of Wight NaturalHistory and Archaeological Society 2, 311–318.

Jackson, M.D., Muggeridge, A.H., Yoshida, S., Johnson, H.D., 2003. Upscaling perme-ability measurements within complex heterolithic tidal sandstones. Mathe-matical Geology 35, 499–520.

Jarzembowski, E.A., 1995. The first insects in Cretaceous (Wealden) amber from theUK. Geology Today 11, 42.

Jarzembowski, E.A., 1999. British amber: a little known resource. Estudiosdel Museo de Ciencias Naturales de Alava, 14 (Numero especial 2), 133–138.

Jarzembowski, E.A., Azar, D., Nel, A., 2008. A new chironomid (Insecta: Diptera) fromWealden amber (Lower Cretaceous) of the Isle of Wight, UK. Geologica Acta 6,285–291.

Jeans, C.V., 2006. Clay mineralogy of the Cretaceous strata of the British Isles. ClayMinerals 41, 47–150.

Jeans, C.V., Mitchell, J.G., Fisher, M.J., Wray, D.S., Hall, I.R., 2001. Age, origin andclimatic signal of English Mesozoic clays based on K/Ar signatures. ClayMinerals 36, 515–539.

Jeans, C.V., Wray, D.S., Mitchell, J.G., Ditchfield, P., 2005. Correlation between thebasal part of the Lower Cretaceous Speeton Clay Formation, Yorkshire, and thePurbeck Limestone Group, Dorset: a bentonite tie line. Proceedings of theYorkshire Geological Society 55, 183–197.

Jones, G.R., 1959. The ostracods of the Wealden shales in the Isle of Wight, and theirrelationship with sedimentation in the Wealden Basin. MSc thesis, University ofAberystwyth, Aberystwyth, Wales, UK.

Jones, T.R., 1878. Notes on some fossil bivalved Entomostraca. Geological MagazineDecade 2 (5), 100–110.

Jones, T.R., 1885. On the Ostracoda of the Purbeck Formation with notes on theWealden species. Quarterly Journal of the Geological Society, London 41, 311–353.

Jones, T.R., 1888. Ostracoda from the Weald Clay of the Isle of Wight. GeologicalMagazine Decade 3 (5), 534–539.

Judd, J.W., 1871. On the Punfield Formation. Quarterly Journal of the GeologicalSociety, London 27, 207–227.

Karner, G.D., Lake, S.D., Dewey, J.F., 1987. The thermal and mechanical developmentof the Wessex Basin, southern England. In: Coward, M.P., Dewey, J.F., Hancock,P.L. (Eds.), Continental Extensional Tectonics, Geological Society, London, pp.517–536, Special Publication 28.

Keen, M.C., 1988. Field excursion to the Cretaceous and Tertiary of the Isle of Wightand the New Forest area Hampshire. In: Keen, M.C., Lord, A.R., Whatley, R.C.(Eds.), Tenth International Symposium on Ostracoda, Aberystwyth 1988. TheMesozoic and Tertiary of Southern England: The Dorset Coast and Isle of Wight,vol. 6. British Micropalaeontological Society Field Guide, pp. 47–79.

Kerth, M., Hailwood, E.A., 1988. Magnetostratigraphy of the Lower CretaceousVectis Formation (Wealden Group) on the Isle of Wight Southern England.Journal of the Geological Society, London 145, 351–360.

Kilenyi, T.I., Allen, N.W., 1968. Marine-brackish bands and their microfauna fromthe lower part of the Weald Clay of Sussex and Surrey. Palaeontology 11, 141–162.

Kilenyi, T.I., Neale, J.W., 1978. The Purbeck/Wealden. In: Bate, R.H., Robinson, E.(Eds.), A Stratigraphical Index of British Ostracoda. Seel House Press, Liverpool,pp. 299–324.

Kinghorn, R.F.F., Selley, R.C., Stoneley, R., 1994. Mupe Bay oil seep demythologized?Marine and Petroleum Geology 11, 124–126.

Kirkaldy, J.F., 1939. The history of the Lower Cretaceous Period in England. Proceed-ings of the Geologists’ Association 50, 379–417.

Kirkaldy, J.F., 1947. The provenance of the pebbles in the Lower Cretaceous rocks.Proceedings of the Geologists’ Association 58, 223–255.

Lees, G.M., Cox, P.T., 1937. The geological basis of the present search for oil in GreatBritain by the D’Arcy Exploration Company Limited. Quarterly Journal of theGeological Society, London 390, 156–194.

Lyell, C., 1871. The Student’s Elements of Geology, tenth edition. Harper, New York,xix + 624 pp.

Mansel-Pleydell, J.C., 1888. Fossil reptiles of Dorset. Proceedings of the DorsetNatural History and Antiquarian Field Club 9, 1–40.

Mantell, G.A., 1827. Illustrations of the Geology of Sussex: Containing a GeneralView of the Geological Relations of the South-eastern part of England; withFigures and Descriptions of the Fossils of Tilgate Forest. Lupton Relfe, London,92 pp.

Mantell, G.A., 1833. The Geology of the South-East of England. Longman, London,xix + 404 pp.

Mantell, G.A., 1844a. The Medals of Creation, or First Lessons in Geology and in theStudy of Organic Remains, Two volumes. Bohn, London, 1016 pp.

Mantell, G.A., 1844b. On the unionidae of the river of the country of the iguanodon.American Journal of Science 47, 403–406.

Mantell, G.A., 1846. Notes on the Wealden Strata of the Isle of Wight, with anaccount of the Bones of Iguanodons and other Reptiles discovered at Brook Pointand Sandown Bay. Quarterly Journal of the Geological Society, London 2, 91–95.

Mantell, G.A., 1847. On the occurrence of a large species of Unio in the Wealdenstrata of the Isle of Wight. London Geological Journal 2, 41–45.

Mantell, G.A., 1848a. A brief notice of organic remains recently discovered in theWealden formation. Quarterly Journal of the Geological Society, London 5, 37–43.

Mantell, G.A., 1848b.. The Wonders of Geology; or, a Familiar Exposition ofGeological Phenomena, sixth edition, vol. 1. Henry Bohn, London.

Mantell, G.A., 1854. Geological Excursions round the Isle of Wight and Along theAdjacent Coast of Dorsetshire; Illustrative of the Most Interesting GeologicalPhenomena and Organic Remains, third edition. Henry Bohn, London.

Martill, D.M., Barker, M.J., 2000. An ammonite steinkern gastrolith from the LowerCretaceous of the Isle of Wight, England. Neues Jahrbuch fur Geologie undPalaontologie, Monatshefte 2000, 186–192.

Martill, D.M., Naish, D., 2001. Dinosaurs of the Isle of Wight. PalaeontologicalAssociation Field Guides to Fossils Series, No. 10. Palaeontological Association,London, 432 pp.

McMahon, N.A., Turner, J., 1998. The documentation of a latest Jurassic–earliestCretaceous uplift throughout southern England and adjacent offshore areas. In:Underhill, J.R. (Ed.), Development, Evolution and Petroleum Geology of theWessex Basin, Geological Society, London, pp. 215–240, Special Publication 133.

McMahon, N.A., Underhill, J.R., 1995. The regional stratigraphy of the southwestUnited Kingdom and adjacent offshore areas with particular reference to themajor intra-Cretaceous unconformity. In: Croker, R.F., Shannon, P.M. (Eds.),The Petroleum Geology of Ireland’s Offshore Basins, Geological Society, London,pp. 323–325, Special Publication 93.

Meyer, C.J.A., 1872. On the Wealden as a fluvio-lacustrine formation, and on therelation of the so-called Punfield Formation to the Wealden and Neocomian.Quarterly Journal of the Geological Society, London 28, 243–255.

Meyer, C.J.A., 1873. Further notes on the Punfield Formation. Quarterly Journal ofthe Geological Society, London 29, 70–76.


Miles, J.A., Downes, C.J., Cook, S.E., 1993. The fossil oil seep in Mupe Bay Dorset: amyth investigated. Marine and Petroleum Geology 10, 58–70.

Monckton, H.W., 1910. The Dorset Coast. In: Monckton, H.W., Herries, R.S. (Eds.),Geology in the Field. The Jubilee Volume of the Geologists’ Association (1858–1908) Edward Stanford, London, pp. 382–413.

Mongin, D., 1961. ‘Unio’ valdensis Mantell, from the Wealden beds of England: itstaxonomic position and geographical distribution. Proceedings of the Malaco-logical Society of London 34, 340–345.

Morris, J., Price, F.G.H., Tawney, E.B., 1882. Excursion to the east end of the Isle ofWight. Proceedings of the Geologists’ Association 7, 185–189.

Morter, A.A., 1978. Weald Clay Mollusca. In: Worssam, B.C., The Stratigraphy of theWeald Clay. Report of the Institute of Geological Sciences 78/11, pp. 19–23.

Nicholas, C.J., Henwood, A.R., Simpson, M., 1993. A new discovery of early Creta-ceous (Wealden) amber from the Isle of Wight. Geological Magazine 130, 847–850.

Norman, M.W., 1887. A Popular Guide to the Geology of the Isle of Wight with aNote on its Relation to that of the Isle of Purbeck. Knight’s Library, Ventnor, 240pp.

Nowell, D.A.G., 1997. Structures affecting the coast around Lulworth Cove, Dorsetand syn-sedimentary Wealden faulting. Proceedings of the Geologists’ Associ-ation 108, 257–268.

Nowell, D.A.G., 1998a. ‘Structures affecting the coast around Lulworth Cove, Dorsetand syn-sedimentary Wealden faulting’ by Nowell (1997): reply. Proceedings ofthe Geologists’ Association 109, 239–240.

Nowell, D.A.G., 1998b. The geology of Lulworth Cove, Dorset. Geology Today 14, 71–74.

Nowell, D.A.G., 2000. The geology of Worbarrow, Dorset. Geology Today 16, 71–75.Oakley, K.P., 1947. A note on Palaeozoic radiolarian chert pebbles found in the

Wealden series of Dorset. Proceedings of the Geologists’ Association 58, 255–258.

Oldham, T.C.B., 1976. Flora of the Wealden plant debris beds of England. Palaeon-tology 19, 437–502.

Parfitt, M.A., Farrimond, P., 1998. The Mupe Bay oil seep: a detailed organicgeochemical study of a controversial outcrop. In: Underhill, J.R. (Ed.), Develop-ment, Evolution and Petroleum Geology of the Wessex Basin, GeologicalSociety, London, pp. 387–397, Special Publication 133.

Parker, A., 1972. Appendix A. Jarosite in Wealden oil-sand from Lulworth Cove.Journal of the Geological Society, London 128, 289–290.

Patterson, C., 1966. British Wealden sharks. Bulletin of the British Museum, NaturalHistory (Geology) 11, 281–350.

Prior, S.V., 1993. X-ray diffraction analysis of a concretion from the Isle of Wight.British Geological Survey Technical Report MPSR/93/92.

Radley, J.D., 1993a. A derived Lower Jurassic clast from the Wealden Group (LowerCretaceous) of the Isle of Wight, southern England. Proceedings of the Geolo-gists’ Association 104, 71–73.

Radley, J.D., 1993b. An occurrence of Viviparus fluviorum in the Wessex Formation(Wealden Group, Lower Cretaceous) of Sandown Bay. Proceedings of the Isle ofWight Natural History and Archaeological Society 11, 97–100.

Radley, J.D., 1994a. Stratigraphy, palaeontology and paleoenvironment of theWessex Formation (Wealden Group, Lower Cretaceous) at Yaverland, Isle ofWight, southern England. Proceedings of the Geologists’ Association 105, 199–208.

Radley, J.D., 1994b. A foraminiferal datum in the Vectis Formation (Wealden Group)of the Isle of Wight, southern England. Proceedings of the Geologists’ Associa-tion 105, 91–97.

Radley, J.D., 1994c. Field Meeting, 24–5 April, 1993: The Lower Cretaceous of the Isleof Wight. Proceedings of the Geologists’ Association 105, 145–152.

Radley, J.D., 1995. Foraminifera from the Vectis Formation (Wealden Group, LowerCretaceous) of the Wessex Sub-basin, southern England: a preliminary account.Cretaceous Research 16, 717–726.

Radley, J.D., 1997a. Geological report 1993–1994. Proceedings of the Isle of WightNatural History and Archaeological Society 13, 107–114.

Radley, J.D., 1997b. New records of unionacean bivalves from the Wessex Formation(Wealden Group, Lower Cretaceous) of Swanage Bay, Dorset. Proceedings of theDorset Natural History and Archaeological Society 118, 167–168.

Radley, J.D., 1998. ‘Structures affecting the coast around Lulworth Cove, Dorset andsyn-sedimentary Wealden faulting’ by Nowell (1997): comment. Proceedingsof the Geologists’ Association 109, 237–238.

Radley, J.D., 1999. Weald Clay (Lower Cretaceous) palaeoenvironments in south-east England: molluscan evidence. Cretaceous Research 20, 365–368.

Radley, J.D., 2002. Distribution and palaeoenvironmental significance of molluscs inthe late Jurassic–early Cretaceous Purbeck Formation of Dorset, southernEngland: a review. In: Milner, A.R., Batten, D.J. (Eds.), Life and environmentsin Purbeck times. Special Papers in Palaeontology 68, pp. 41–51.

Radley, J.D., 2005. Derived fossils in the southern English Wealden (non-marineearly Cretaceous): a review. Cretaceous Research 26, 657–664.

Radley, J.D., 2006. A Wealden guide 2: the Wessex Sub-basin. Geology Today 22,187–193.

Radley, J.D., 2009. Archaic-style shell concentrations in brackish-water settings:Lower Cretaceous (Wealden) examples from southern England. CretaceousResearch 30, 710–716.

Radley, J.D., Barker, M.J., 1998a. Stratigraphy, palaeontology and correlation of theVectis Formation (Wealden Group, Lower Cretaceous), at Compton Bay, Isle ofWight, southern England. Proceedings of the Geologists’ Association 109, 187–195.

Radley, J.D., Barker, M.J., 1998b. Palaeoenvironmental analysis of shell beds in theWealden Group (Lower Cretaceous) of the Isle of Wight, southern England: aninitial account. Cretaceous Research 19, 489–504.

Radley, J.D., Barker, M.J., 2000a. Palaeoenvironmental significance of storm coqui-nas in a Lower Cretaceous coastal lagoonal succession (Vectis Formation, Isle ofWight, southern England). Geological Magazine 137, 193–205.

Radley, J.D., Barker, M.J., 2000b. Palaeoenvironmental and palaeoecological signifi-cance of shell beds in a Lower Cretaceous meanderplain succession: the WessexFormation of the Isle of Wight, southern England. Proceedings of the Geologists’Association 111, 133–145.

Radley, J.D., Barker, M.J., Harding, I.C., 1998a. Palaeoenvironment and taphonomy ofdinosaur tracks in the Vectis Formation (Lower Cretaceous) of the Wessex Sub-basin, southern England. Cretaceous Research 19, 471–487.

Radley, J.D., Barker, M.J., Munt, M.C., 1998b. Bivalve trace fossils (Lockeia) from theBarnes High Sandstone (Wealden Group, Lower Cretaceous) of the Wessex Sub-basin, southern England. Cretaceous Research 19, 505–509.

Radley, J.D., Gale, A.S., Barker, M.J., 1998c. Derived Jurassic fossils from the VectisFormation (Lower Cretaceous) of the Isle of Wight, southern England. Proceed-ings of the Geologists’ Association 109, 81–91.

Radley, J.D., Munt, M.C., Barker, M.J., 2006. Wealden (non-marine Lower Cretaceous)molluscs from southern England: faunas, palaeobiogeography and palaeoen-vironments. In: Ninth International Symposium on Mesozoic Terrestrial Eco-sytems and Biota, Abstracts and Proceedings. Natural History Museum, London,pp. 105–109.

Reid, C., Strahan, A., 1889. The geology of the Isle of Wight, second edition. Memoirof the Geological Survey of England and Wales. HMSO, London, xiv + 349 pp.

Relf, F.J., 1916. An investigation of some Wealden sands. Geological Magazine, Newseries, Decade 6 (3), 295–302.

Robinson, S.A., Andrews, J.E., Hesselbo, S.P., Radley, J.D., Dennis, P.F., Allen, P., 2002.Atmospheric pCO2 and depositional environment from stable-isotope geo-chemistry of calcrete nodules (Barremian Lower Cretaceous, Wealden Beds,England). Journal of the Geological Society, London 159, 215–224.

Robinson, S.A., Hesselbo, S.P., 2004. Fossil-wood carbon-isotope stratigraphy of thenon-marine Wealden Group (Lower Cretaceous, southern England). Journal ofthe Geological Society, London 161, 133–145.

Ruffell, A.H., 1988. Palaeoecology and event stratigraphy of the Wealden-LowerGreensand transition in the Isle of Wight. Proceedings of the Geologists’Association 99, 133–140.

Ruffell, A.H., 1992. Early to mid-Cretaceous tectonics and unconformities of theWessex Basin (southern England). Journal of the Geological Society, London149, 443–454.

Ruffell, A.H., Batten, D.J., 1990. The Barremian-Aptian arid phase in western Europe.Palaeogeography, Palaeoclimatology, Palaeoecology 80, 197–212.

Ruffell, A.H., Batten, D.J., 1994. Uppermost Wealden facies and Lower GreensandGroup (Lower Cretaceous) in Dorset, southern England: correlation andpalaeonvironment. Proceedings of the Geologists’ Association 105, 53–69.

Ruffell, A.H., Garden, R., 1997. Tectonic controls on the variation in thickness andmineralogy of pebble-beds in the Lower Greensand Group (Aptian–Albian) ofthe Isle of Wight, southern England. Proceedings of the Geologists’ Association108, 215–229.

Ruffell, A.H., Harvey, M., 1993. Field excursion to the Cretaceous and Cenozoic ofRedcliff (Sandown) and Whitecliff Bay, Isle of Wight, 5th January 1992. Pro-ceedings of the Ussher Society 8, 77–78.

Ruffell, A.H., Worden, R., 2000. Palaeoclimate analysis using spectral gamma-raydata from the Aptian (Cretaceous) of southern England and southern France.Palaeogeography, Palaeoclimatology, Palaeoecology 115, 265–283.

Sarjeant, W.A.S., Delair, J.B., Lockley, M.G., 1998. The footprints of Iguanodon: ahistory and taxonomic study. Ichnos 6, 183–202.

Sedgwick, A., 1822. On the geology of the Isle of Wight & c. Annals of Philosophy 19,329–355.

Selden, P.A., 2002. First British Mesozoic spider, from Cretaceous amber of the Isle ofWight, southern England. Palaeontology 45, 973–983.

Selley, R.C., Stoneley, R., 1987. Petroleum habit in south Dorset. In: Brooks, J.,Glennie, K. (Eds.), Petroleum Geology of North West Europe. Graham andTrotman, London, pp. 139–148.

Sellwood, B.W., Wilson, R.C.L., West, I.M., Clitheroe, A., 1991. Jurassic sedimentaryenvironments of the Wessex Basin. 13th Congress, International Association ofSedimentologists, Nottingham, England, p. 89.

Simpson, M.I., 1985. The stratigraphy of the Atherfield Clay Formation (LowerAptian, Lower Cretaceous) at the type and other localities in southern England.Proceedings of the Geologists’ Association 57, 239–250.

Simpson, M.I., 1999. Appendix: The Isle of Wight Wealden amber. Estudios delMuseo de Ciencias Naturales de Alava, 14 (Numero especial 2), 138–140.

Sohn, I.G., Anderson, F.W., 1964. The ontogeny of Theriosynoecum fittoni (Mantell).Palaeontology 7, 72–84.

Sowerby, J. de C., 1836. Observations on some of the strata between the Chalk andthe Oxford Oolite in the Southeast of England. In: Fitton, W.H., Transactions ofthe Geological Society of London Second Series 4, pp. 335–349.

Sowerby, J. de C., 1846. The Mineral Conchology of Great Britain, vol. 7. Sowerby,London, 80 pp.

Steel, J.E., 1986. Preliminary palaeomagnetic results from the Isle of Wight. Geo-physical Journal of the Royal Astronomical Society 85, 260.

Stewart, D.J., 1978a. The sedimentology and palaeoenvironment of the WealdenGroup of the Isle of Wight, southern England. PhD thesis, Portsmouth Polytech-nic, Portsmouth, UK.


Stewart, D.J., 1978b. Ophiomorpha: a marine indicator? Proceedings of the Geol-ogists’ Association 89, 33–41.

Stewart, D.J., 1981a. A field guide to the Wealden Group of the Hastings area and theIsle of Wight. In: Elliott, T., Field guides to modern and ancient fluvial systems inBritain and Spain. International Fluvial Conference, University of Keele pp. 3.1–3.32.

Stewart, D.J., 1981b. A meander-belt sandstone of the Lower Cretaceous of SouthernEngland. Sedimentology 28, 1–20.

Stewart, D.J., 1983. Possible suspended-load channel deposits from the WealdenGroup (Lower Cretaceous) of Southern England. Special Publications of theInternational Association of Sedimentologists 6, 369–384.

Stewart, D.J., Ruffell, A., Wach, G., Goldring, R., 1991. Lagoonal sedimentation andfluctuating salinities in the Vectis Formation (Wealden Group, Lower Cretaceous)of the Isle of Wight, southern England. Sedimentary Geology 72, 117–134.

Stinton, F., 1971. Easter field meeting in the Isle of Wight. Proceedings of theGeologists’ Association 82, 403–410.

Strahan, A., 1898. The geology of the Isle of Purbeck and Weymouth. Memoir of theGeological Survey, England and Wales. HMSO, London, xi + 278 pp.

Sweetman, S.C., 2006. A gobiconodontid (Mammalia, Eutriconodonta) from theEarly Cretaceous (Barremian) Wessex Formation of the Isle of Wight, southernBritain. Palaeontology 49, 889–897.

Sweetman, S.C., 2008. A spalacolestine spalacotheriid (Mammalia, Trechnotheria)from the Early Cretaceous (Barremian) of southern England and its bearing onspalacotheriid evolution. Palaeontology 51, 1367–1385.

Sweetman, S.C., Insole, A.N., 2010. The plant debris beds of the Early Cretaceous(Barremian) Wessex Formation of the Isle of Wight, southern England: theirgenesis and palaeontological significance. Palaeogeography, Palaeoclimatology,Palaeoecology 292, 409–424.

Sweetman, S.C., Martill, D.M., 2010. Pterosaurs of the Wessex Formation (EarlyCretaceous, Barremian) of the Isle of Wight, southern England: a review withnew data. Iberian Geology 36, 225–242.

Sweetman, S.C., Underwood, C.J., 2006. A neoselachian shark from the non-marineWessex Formation (Wealden Group: Early Cretaceous, Barremian) of the Isle ofWight, southern England. Palaeontology 49, 457–465.

Twitchett, R.J., 1995. A new Lower Cretaceous insect fauna from the Vectis Forma-tion (Wealden Group) of the Isle of Wight. Proceedings of the Geologists’Association 106, 47–51.

Underhill, J.R. (Ed.), 1998. Development, Evolution and Petroleum Geology of theWessex Basin, Geological Society, London, pp. vi+420, Special Publication 133.

Underhill, J.R., 2002. Evidence for structural controls on the deposition of the lateJurassic–early Cretaceous Purbeck Limestone Group, Dorset, southern England.In: Milner, A.R., Batten, D.J. (Eds.), Life and Environments in Purbeck Times.Special Papers in Palaeontology 68, pp. 21–40.

Underhill, J.R., Paterson, S., 1998. Genesis of tectonic inversion structures: seismicevidence for the development of key structures along the Purbeck–Isle of Wightdisturbance. Journal of the Geological Society, London 155, 975–992.

Underhill, J.R., Stoneley, R., 1998. Introduction to the development, evolution andpetroleum geology of the Wessex Basin. In: Underhill, J.R. (Ed.), Development,Evolution and Petroleum Geology of the Wessex Basin. Geological Society ofLondon, Special Publication 133, pp. 1–18.

Wach, G.D., Ruffell, A.H., 1991. Sedimentology and sequence stratigraphy of aLower Cretaceous tide and storm-dominated clastic succession, Isle of Wightand S.E. England. 13th Congress International Association of Sedimentologists.Nottingham, England, 100 pp.

Waite, S.T., 1964. Geological section report for 1963. Proceedings of the Isle of WightNatural History and Archaeological Society 5, 324.

Waite, S.T., 1965. Geological section report for 1965. Proceedings of the Isle of WightNatural History and Archaeological Society 5, 451–453.

Watson, J., 1977. Some Lower Cretaceous conifers of the Cheirolepidaceae fromU S.A. and England. Palaeontology 20, 715–749.

Watson, J., Alvin, K.L., 1996. An English Wealden floral list, with comments onpossible environmental indicators. Cretaceous Research 17, 5–26.

Watson, J., Cusack, H.A., 2005. Cycadales of the English Wealden. Monograph of thePalaeontographical Society 158, 1–189.

Watson, J., Harrison, N.A., 1998. Abietites linkii (Romer) and Pseudotorellia hetero-phylla Watson: coniferous or ginkgoalean? Cretaceous Research 19, 239–278.

Watson, J., Lydon, S.J., 2004. The bennettitalean trunk genera Cycadeoidea andMonanthesia in the Purbeck, Wealden and Lower Greensand of southern Eng-land: a reassessment. Cretaceous Research 25, 1–26.

Watson, J., Lydon, S.J., Harrison, N.A., 2001. A revision of the English Wealden FloraIII: Czekanowskiales, Ginkgoales and allied Coniferales. Bulletin of the NaturalHistory Museum, London (Geology) 57, 29–82.

Watson, J., Sincock, C.A., 1992. Bennettitales of the English Wealden. Monograph ofthe Palaeontographical Society 145, 1–228.

Webb, B., 2001. The White Rock. The Geological Society of the Isle of WightNewsletter 2 (4), 18–27.

Webster, T., 1816. Additional observations, chiefly geological, on the Isle of Wight,and adjacent coast of Dorsetshire: in a series of letters to Sir H Englefield. In:Englefield, H.C., A Description of the Principal Picturesque Beauties, Antiquitiesand Geological Phenomena of the Isle of Wight, Paybe and Foss, London,xxvii+238 pp.

Weston, C.H., 1848. On the geology of Ridgway near Weymouth. Quarterly Journalof the Geological Society, London 4, 245–256.

Weston, C.H., 1852. On the sub-escarpments of the Ridgway range, and theircontemporaneous deposits in the Isle of Portland. Quarterly Journal of theGeological Society, London 8, 110–120.

White, H.J.O., 1921. A short account of the geology of the Isle of Wight. Memoirs ofthe Geological Survey of Great Britain. HMSO, London, viii + 201 pp.

Wilkins, E.P., 1859. A Concise Exposition of the Geology, Antiquities and Topogra-phy of the Isle of Wight. T. Kentfield, Newport, 98 pp.

Wilkinson, I.P., 2002. A catalogue of specimens deposited in the PalaeontologicalCollections of the British Geological Survey: 1 Type and figured ‘Purbeck’ and‘Wealden’ Ostracoda. British Geological Survey Research Report, RR/01/03, 66pp.

Wilkinson, I.P., 2008. The effect of environmental change on early Aptian ostracodfaunas in the Wessex Basin, southern England. Revue de Micropaleontologie 51,259–272.

Wimbledon, W.A., Allen, P., Fleet, A.J., 1996. Penecontemporaneous oil-seep in theWealden (early Cretaceous) at Mupe Bay, Dorset. Sedimentary Geology 102,213–220.

Witton, M.P., Martill, D.M., Green, M., 2009. On pterodactyloid diversity in theBritish Wealden (Lower Cretaceous) and a reappraisal of ‘‘Palaeornis’’ cliftiiMantell, 1844. Cretaceous Research 30, 676–686.

Worssam, B.C., Ivimey-Cook, H.C., 1971. The stratigraphy of the Geological SurveyBorehole at Warlingham Surrey. Bulletin of the Geological Survey of GreatBritain 36, 1–146.

Wright, J.L., Barrett, P.M., Lockley, M.G., Cook, E., 1998. A review of the earlyCretaceous terrestrial vertebrate track-bearing strata in England and Spain.In: Lucas, S.G., Kirkland, J.I., Estep, J.W. (Eds.), Lower and Middle CretaceousTerrestrial Ecosystems. New Mexico Museum of Natural History and ScienceBulletin 14, pp. 143–154.

Wright, V.P., Taylor, K.G., Beck, V.H., 2000. The paleohydrology of Lower Cretaceousseasonal wetlands, Isle of Wight, southern England. Journal of SedimentaryResearch 70, 619–632.

Yoshida, S., Jackson, M.D., Johnson, H.D., Muggeridge, A.H., Martinius, A.W., 2001.Outcrop studies of tidal sandstones for reservoir characterization (LowerCretaceous Vectis Formation, Isle of Wight, Southern England). In: Martinsen,O., Dreyer, T. (Eds.), Sedimentary Environments of Offshore Norway–Palaeo-zoic to Recent. NPF Society Special Publication 10. Elsevier, Amsterdam, pp.233–257.

Documents

The Wealden (non-marine Lower Cretaceous) of the Wessex Sub-basin, southern England