WJEC A2 Geology

WJEC A2 GeologyBGS Mapwork

I.G.Kenyon

Recognising Geological Structures

Moreton-in-Marsh1:50,000 Sheet 217

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+

Horizontal beds

Evidence + symbols

Bed outcrops run parallel to contour lines

Outcrop pattern controlled by relief/topography

Youngest bed

Oldest bed LLi

No strike and dip values can be given

Moreton-in-Marsh1:50,000 Sheet 217

Graben

Horst

Ticks on faults indicate downthrown side

Graben

Moreton-in-Marsh1:50,000 Sheet 217

Outliers-areas of younger rock completely surrounded by older rock

Cheddar 1:25,000 Sheet ST 45

Older Carboniferous

Limestone

Younger Triassic red mudstone

Inlier-an area of older rock completely surrounded by younger rocks

Unusually this inlier also forms a hill

Anticlinal Axis

N

South side dips more gently (dips 25-30°) Outcrops wider

North side dips more steeply (dips 42-60°) Outcrops narrower

Slight plunge to the east as core bed gets narrower in outcrop

Cheddar 1:25,000 Sheet ST 45

Asymmetrical Anticline

Oldest bed in the core of the fold

Repeated outcrop pattern, only core bed

is not repeated

Cheddar 1:25,000 Sheet ST 45

DCg is a basal conglomerate and is unconformable on the

older carboniferous rocks

DCg shows angular overstep here as it extends

over several older rocks

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Upper younger series are horizontal

Lower older series dip North 60-80° and strike East-West

MMG overlaps DCg here

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Monmouth 1:50,000 Sheet 233

C3 quartz conglomerate forms a parallel unconformity between the upper and lower old red sandstone

Beds above and below unconformity have parallel outcrop patterns and

the same dip and strike values

Angular overstep unconformity here

between the carboniferous limestone and the upper

coal measures

Craven Arms 1:25,000 Sheet SO48 Solid & Drift

Account for the V shaped pattern of outcrop of bed b7b here

Malmesbury One inch Sheet 251 Solid & Drift

Describe the strike and dip of the Carboniferous beds here

Identify the relationship between beds d5 and f6 here

Malmesbury One inch Sheet 251, Solid & Drift

Describe the main fold structure here, refer to strike and dip values, symmetry and plunge

Name this feature

Haverfordwest 1:50,000 Sheet 228

Describe the main fold structure here, refer to strike and

dip values, symmetry and plunge

Chepstow 1:50,000 Sheet 250

Describe the main fold structure here, refer to strike and dip

values, symmetry and plungeApproximate

position of fold axis

Chepstow 1:50,000 Sheet 250This fault dips east at 79°,

identify the fault type

Identify this deposit and account for its distribution

on this map extract

Haverfordwest 1:50,000 Sheet 228

Describe and identify the main fold structure in the map extract above. Refer to dip and strike values, symmetry and plunge where appropriate

Identify this feature

Haverfordwest 1:50,000 Sheet 228

Identify the relationship between beds (b4 and d4) and (d2 and d4) in this box

Describe and identify the main fold structure in the map extract above. Refer to dip and strike

values, symmetry and plunge where appropriate

Hawes 1:50,000 Solid & DriftDescribe the evidence

on the map for the Carboniferous beds GL

and DBL being horizontal

Describe the fold structures in the InG beds within this box

Chepstow 1:50,000 Sheet 250

Describe the strike and dip of the Carboniferous

beds BRL, BRD, GuO and CDLin this box

Identify an angular unconformity on the map extract and locate examples of overstep and overlap

Cockermouth 1:50,000 Sheet 23

Identify an area of Step-Faulting and a Horst Block on the map extract

If the Crummock and Waverbank Faults dip North East, what

type of faults are they?

Ayr 1:50,000 Sheet 14(W)

If this fault dips steeply to the SSW, what is the type of fault?

Ayr 1:50,000 Sheet 14(W)

Describe the main fault trends on the extract above. Identify 2 Grabens, 2 Horst Wedges and an area of Step Faulting

Carmarthen 1:50,000 Sheet 229 Solid

This fault plane dips steeply to the South East. Identify the type of fault

This fault plane dips steeply to the South East. Identify the type of fault

Carmarthen 1:50,000 Sheet 229 Solid

Name the types of faults F1 and F2 on the cross section above

F1 F2

Alloa 1:50,000 Sheet 13 Solid

Account for the repeated outcrop of bed dc2 on the map extract above

Alloa 1:50,000 Sheet 13 Solid

Describe and identify the major fold structure on the map extract above. Refer to dips and strikes, symmetry and plunge where appropriate.

Alloa 1:50,000 Sheet 13 Solid

The Ochil Fault dips at a high angle to the South. Which is the downthrown side? What type of fault is the Ochil Fault?

Account for the variation in width of the metamorphic aureole

Metamorphic Aureole

Brough-under-Stainmore 1:50,000 Sheet 31 Solid

Describe the outcrop of the quartz dolerite qD and outline the likely nature of this igneous intrusion

Chapel en le Frith 1:50,000 Sheet 99 Solid

Identify 2 major fold structures on the map extract above Refer to dip and strike, symmetry and plunge where appropriate

Chapel en le Frith 1:50,000 Sheet 99 Solid

Describe the relationship between geological structure and topography on the cross section above.

Comment on the areas highlighted by the boxes.

Winchester 1:50,000 Solid & Drift

Identify the major fold structure on the map extract above

Cross section shown on next slide

a

b

a b

Winchester 1:50,000 Solid & Drift

Describe and explain the relationship between topography and structure on the cross section above

Grampound Grit

Falmouth Series

Mylor Series

Portscatho Series

Falmouth 1:50,000 Sheet 352 Solid & Drift

Truro School

Inliers-outcrops of older rock completely surrounded by younger rocks

Quartz Porphyry Dykes

River Allen

River Kenwyn

Mica-rich dykes (Minette)

Sediments are Devonian 408-360 Ma

The End

Ash deposits of the Las Canadas Volcano, Tenerife, Canary Islands