QUATERNARY RESEARCH 9, 363-367 (1978)

BOOK REVIEWS The Quaternary History of the Irish Sea. 6 k.-

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sediments are of Ipswichian (last interglacial) age. Kidson and M. J. Tooley. Geological Journal pecial The mapping of this extensive area of till has added Issue No. 7, See1 House Press, Liverpool, 1977. Price greatly to the certainty of reconstructions of the limit .$33.OO/fl6.00. of the last glaciation, especially in South Wales. It

: has sharpened the controversy over the situation of In a brief review, soon after publication, I have the Isle of Man, for Thomas argues that the central

already complained about the limited value of this i part of the island above 180 m was unglaciated in the book to the uninitiated reader. Like so many symposia, ’

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last glaciation. This requires a slope to the ice mar- it provides a dozen disparate views, in this case so gin to the south of no more than 100 m in 300 km, totally contradicting each other that it is impossible 1 far below the gradients of marginal tongues of exist- to see which might be the most probable. The editorsv ing ice sheets. have done very little to resolve this cons 7 The reporting of recent work on the floor of the Irish hence my frustration.

I welcome the chance to write at greater length, less for the opportunity to justify my rather harsh

conclusions than because I believe some suggestions are needed about the way forward. The panacea of “more research” will hardly do here, for this volume

kundoubtedly reports much new research, yet we are if anything in a deeper mess than we were when Frank Mitchell reviewed the problems ofthe Irish Sea in 1972.

The book reports one of three symposia held by the Subcommission on the Shorelines of Northwestern Europe of the Commission on Shorelines of INQUA. The editors, authors, and publisher are to be con- gratulated on getting the book out between the Upp- sala Symposium in March and the INQUA Congress in August 1977. When it comes down to it, not a lot has been done on the shorelines of the Irish Sea, and several of the contributors have nothing to say on the subject at all! In any case, the entire Quater- nary history of the Irish Sea is in such chaos that prog- ress on the shorelines (especially dating the older shorelines) is difficult without more agreement about the glacial succession. As a result the book is at least as concerned with this broad issue as it is with shore- lines themselves. Since the North Sea and the Irish Sea did not wholly exhaust the British coasts, oppor- tunity has been taken to include three papers on more peripheral areas, northwest Scotland, the Southwest Peninsula (Somerset, Devon, and Cornwall), and the English Channel Coast (as far east as Dungeness). Since these essays have more to say on shorelines than most of the others, the additions are welcome.

The lack of agreement over the dating of the glacial episodes on either side of the Irish Sea has so far been the main difficulty. Recent work on the tloor of the Irish Sea has changed this a great deal, since it has not only estabIis&l the geology and structural his- tory of the area (well summarized here), but it has also proved two tills over most of the southern area, separated by a very thick interglacial marine sequence. The view is that this represents a penultimate glacia- tion, last interglacial, last glaciation sequence, al- though we cannot yet be sure that the interglacial

Sea will be the main addition this volume brings for those already well-read in the Quatemary of the area. There is little else that can be called new, and that is why I have complained that with little fresh evidence, the reader at least expects a fresh attempt to recon- cile conflicting views. It is also odd how little there is here on past sea levels; two-thirds of the book is about the glacial succession (or even the pre-Quater- nary geology), and only one-third refers to the formal topic of Quatemary sea levels.

That third is the core of the original symposium, given its title and aims. Yet we lack any general intro- duction to the problems of raised (and submerged) shorelines, and the authors have no consensus of sea level changes during even the Flandrian (Holocene) on which to hang their own evidence. More seriously, in an area presumably affected by both glacio-isostatic deformation and glacio-eustatic changes, only one author shows any sign that he understands that in such a situation raised beaches are diachronous. Indeed, some authors virtually ignore glacio-isostatic effects, mentioning them almost as an afterthought. Others confidently suggest frequent reoccupation of inter- glacial wave-cut benches, a conceivable but hardly a probable situation. While most authors suggest at most a few meters of glacio-isostatic depression, Stephens and McCabe throw out the possibility of 80 m of recovery in the last 12,000 years. Where? Why? They do not tell us.

This is the central problem of the shoreline material here. As a bare minimum, one needs a date and a height. Most of these authors have few if any sites where both are available; others quote heights that given their location and age are surely greatly affected by iso- static adjustment. One problem here is the shortage of datable material, but it has been compounded by the difficulty in getting organic material dated in the U.K. over the last decade. So until we have more good sites, more dates, and some rather more careful interpretation, we are forced to admit that we know very little about sea levels in the Quaternary. The one exception is the last interglacial (Ipswichian). For the Ipswichian, Bowen argues convincingly that

363 0033-5894/78/0093-0363$02.0010 Copyright Q 1978 by the Univenity of Washington. Au rights of reproduction in any form reserved.

364 BOOK REVIEWS

the beach at about 10 m (it ranges from 3.6 to 15 m), which can be firmly dated in cave deposits in South Wales, is of last interglacial (Ipswichian) age. Con- trasting lithologies in the overlying periglacial head (colluvium) are explained in terms of the sequence of soil, subsoil, and rock successively exposed and trans- ported as the Devensian denudation continued. Both Mitchell and Wirtz have assumed these contrasts implied two or more distinct periods of periglaciation. The same feature occurs in Ireland where it was orig- inally regarded as preglacial and then as Hoxnian, and, as Synge admits, could just as well be Ipswichian if one removes all of the bold guesses and sticks to the very few dated deposits that can be related to it. Again in Devon, Kidson accepts that the Freming- ton site is most simply interpreted as an Ipswichian beach with Wolstonian giant erratics, Wolstonian till, and a Devensian head. Finally, Mottershead has fossil evidence that the 30- to 35-m beach in Sussex is of Hoxnian age and the 12- to 14-m beach is Ipswichian. Both Mottershead and Kidson have evidence that the late Ipswichian transgression reached +20 m.

Our knowledge of Holocene sea levels is very incom- plete partly because, as Bowen notes, the evidence has not been examined in most areas. The main excep- tion is Tooley’s work along the Lancashire coast, and his transgressions and regressions. Every peat marks a regression, every marine clay a transgression. Fair- bridge would be pround of his wiggles! The matter is complex, partly because he does not present much of his evidence in this particular paper, and partly because no other author adopts his approach. For the rest, the choice is the classic one between a smooth Flandrian curve to present sea level or a postglacial high sea level of 4 m or so. This on the evidence here seems to be borrowed (selectively) from the literature: there is no local evidence for it that is not as easily interpreted as isostatic adjustments. In this connection Kidson presents a useful curve showing the Flandrian transgression in the Somerset levels. He notes that it shows no postglacial level higher than today and, most interestingly, that it fits the evidence from West Wales. The curve seems to be a good one, and although it does not meet all of Bloom’s stringent criteria, has been corrected for compaction. He concludes that this suggests no isostatic movement in West Wales and no tilting between the two areas. For the period covered by these data this seems a fair conclusion, and it seems that if there was glacio-isostatic depres- sion of Devensian age in West Wales, the land must have recovered by about 10,000 B.P. But Kidson’s further suggestion that Southern England shows “general signs of stability for much of the Quater- nary” rests only on the morphological feature at 200 m attributed to the Calabrian. Given the Tertiary sedi- mentary basins, with three of the four south of Angle- sey exceeding 500 m depth, and given the repeated loading and unloading by the British Ice Sheet, the view needs firmer evidence if it is to be sustained.

In view of the very muddled evidence presented by the authors in this volume, it is a pity no one set out a framework for future research. So far as Qua- ternary sea levels are concerned, there are at least three ways in which progress could be made. First, we require an extension of the approach of Kidson in the Somerset levels, so that those areas departing from this sea-level curve may be identified. Workers here will need to be aware that the limit of the area with a common Flandrian history will vary with age, but it will at least limit in time and space the areas subject to glacio-isostacy and possibly other Quater- nary tectonic mobility. Second, there is everything to be said for testing (to destruction?) Bowen’s gen- eralizing hypothesis that the 10-m interglacial marine beach buried by head in the south, and no doubt by till in the north, is of Ipswichian age. If that feature can be traced northward, we may learn much about relative displacements of level. Third, far more prog- ress must be made in establishing not only the limits of glacio-isostatic movements but also the values of recovery. Here a number of different approaches are possible, and some have already been tried in the literature. It is senseless to treat the whole of the Irish Sea basin as if it simply showed the effects of glacio-eustasy-yet that is the dominant approach at present. Finally, while some problems may have to await an improved glacial chronology for the Irish Sea, the approaches outlined here can probably go ahead without it. Given the present chaos. that is fortunate.

KEITH CLAYTON School of Environmental Science,

University of East Anglia, Norwich. England

Glacial Till. Robert F. Legget, Editor. Special Publi- cation No. 12, The Royal Society of Canada, Ottawa, 1976, 412 pp.. $20.00

This volume consists of 22papers that were presented at a symposium held on February 17 and 18, 1975, in Ottawa under the auspices of the Royal Society of Can- ada, the Canadian Geoscience Council, and the INQUA Commission on Genesis and Lithology of Quatemary Deposits. The symposium, in which applied studies of till were emphasized, was intended to complement the earlier Conference on the Geology of Tills held in I%9 at Ohio State University, in which purely geological aspects of till were stressed (the proceedings of the latter conference were published in the volume, Till: a Symposium, Ohio State University Press, Columbus, Ohio, 1971). The subtitle of the volume is “An Inter- disciplinary Study,” and the “disciplines” are glacial geology, pedology, mineral exploration, and geotech- nical engineering. The papers are grouped into sections corresponding to these four fields: an invited keynote