List of Figures
Chapter 1 Introduction
Fig. 1. Simplified Geologic Map of Wales
Fig. 2. The changing position of Wales.
Fig. 3. The Welsh Basin in Ordovician to Silurian times.
Fig. 4. The Ice Ages of Wales.
Chapter 2 Northwest Wales
Fig. 1. Geologic sketch map of northwest Wales.
Anglesey
Fig. 2. Geologic sketch map of Anglesey
Fig. 3. Geologic sketch map of southwest Anglesey.
Fig. 4. Section along the A5 across Anglesey.
Fig. 5. Sketch of Roches Moutonée.
Fig. 6. Llanddwyn Island. Pillows in Precambrian lava flow.
Fig. 7. Geologic sketch map of Holy Island.
Fig. 8. Section across Holy Island showing its two sets of folds.
Fig. 9. Holy Island.Sketch of folds on South Stack.
Fig. 10. Treaddur Bay. Early folds in volcanic ash.
Fig. 11. Geologic sketch map of northern Anglesey.
Fig. 12. Geologic sketch map of Cemaes Bay.
Fig. 13. Parys mine map.
Fig. 14. Geologic sketch map of southeast Anglesey.
Fig. 15. Red Wharf Bay. Large sandstone pipes in Carboniferous Limestone.
Fig. 16. Red Wharf Bay. A section of a large pipe in the limestone in cliff.
Lleyn Peninsula
Fig. 17. Geologic sketch map of the Lleyn peninsula.
Fig. 18. Criccieth Castle on an Ordovician dolerite sill.
Fig. 19. Columnar jointing in Ordovician lavas. Beach below Criccieth castle.
Fig. 20. The town of Criccieth above cliff of glacial till.
Fig. 21. The geology of the headland at Uwchmynydd.
Fig. 22. Uwchmynydd. Large blocks of white quartzite in a mixture of schists and volcanic blocks.
Fig. 23. Morfa Nefyn lighthouse. Pillows in Precambrian basalt (Gwna group).
Fig. 24. Trevor. Granite quarry in Ordovician granite on Yr Eifl.
Snowdonia
Fig. 25. Geological map of Snowdonia.
Fig. 26. Sketch of the hills west of Conwy.
Fig. 27. Blaenau Ffestiniog. Slate cribs.
Fig. 28. Llanrwst Bridge.
Fig. 29. Geologic sketch map of Nant Ffrancon pass.
Fig. 30. Cross section along the A5 from Capel Curig through the Nant Ffrancon pass.
Fig. 31. Nant Ffrancon pass. The Pitts Head Tuff near Roman Bridge,
Fig. 32. Nant Ffrancon valley from near the Youth Hostel at the west end of Llyn Ogwen.
Fig. 33. Fence of slate from the Penrhyn quarries.
Fig. 34. Geologic sketch map of Llanberis Pass.
Fig. 35. Cross section along the Llanberis pass.
Fig. 36. View of rocks west of Llanberis pass.
Fig. 37. Llanberis Pass. Volcanic bombs in Ordovician volcanic ash.
Fig. 38. Dinorwic slate quarries.
Fig. 39. Llanberis. Vivian slate quarry. Volcanic dyke in slate.
Fig. 40. Llanberis. Precambrian Padarn volcanic ash outcrops
Fig. 41. Geologic sketch map of Pass of Rhydd-ddu.
Fig. 42. Mynydd Mawr.
Harlech Dome
Fig. 43. Geologic sketch map of the Harlech Dome.
Fig. 44. The Rhinog Mountains.
Fig. 45. Barmouth. Convolutions in a turbidite sandstone of the Cambrian Maentwrog Beds.
Fig. 46. Barmouth. Cambrian slate with vertical cleavage below Parkington Terrace.
Fig. 47. Barmouth. Coarse sands of the Rhinog Grits on the path above St. John's church,
Fig. 48. Barmouth. Thick bedded sandstone of the Rhinog Grits.
Fig. 49. Harlech Castle on an old sea cliff eroded into the Rhinog Grits.
Fig. 50. Harlech Castle. Turbidite sandstone in slate of the Cambrian Rhinog Grits.
Fig. 51. Morfa Harlech. A fault separates Cambrian rocks from a low plain,
Cadair Idris Range
Fig. 52. Geologic sketch map of Cadair Idris Range.
Fig. 53. Tal-y-Llyn valley.
Fig. 54. Cadair Idris from the Barmouth estuary.
Chapter 3 Northeast Wales
Fig. 1. Geologic sketch map of northeastern Wales.
Fig. 2. Geologic cross section of northeast Wales.
Fig. 3. Geologic sketch map of area from Llangollen to Betws-y-Coed.
Fig. 4. Geologic sketch map of area from Chester to Conwy.
Fig. 5. Llandudno. Cliffs of Carboniferous Limestone.
Fig. 6. Geologic sketch map of area from Llangollen to Rhyll and the Vale of Clwyd.
Fig. 7. Sketch of view northeast from a quarry in Silurian slate near Horseshoe Pass (319 347).
Fig. 8. Sketch of view from Craig Fawr.
Fig. 9. Geological sketch map of the central Clwydian Range.
Fig. 10. Geological sketch map of the Denbigh Moors.
Fig. 11. Denbigh. Banded Silurian siltstone.
Chapter 4 Central Wales
Fig. 1. Geologic sketch map of Central Wales
Fig. 2. Geologic sketch map of the area of the A487 between New Quay and Machynlleth.
Fig. 3. New Quay. Turbidite sandstone at the west end of the harbour.
Fig. 4. New Quay. Turbidite sandstone.
Fig. 5. Aberaeron. Turbidite sandstones. South end of beach.
Fig. 6. Aberarth. Sea cliffs in glacial till.
Fig. 7. Aberarth. Ripped up and contorted turbidite layer.
Fig. 8. Aberystwyth. The cliff at the north end of the esplanade.
Fig. 9. Aberystwyth. Ten-centimetre-thick sandstone layers alternating with mudstone.
Fig. 10. Aberystwyth. Tracks of small animals on the underside of a bed in the deep water Silurian sandstone.
Fig. 11. Aberystwyth. Scour marks on the underside of one of a sandstone bed. Fig. 12. Colour banded Silurian slates at Borth.
Fig. 13. Borth.Close up of the banded Silurian slate.
Fig. 14. Machynlleth. Colour-banded Silurian slate.
Fig. 15. Geologic sketch map of the area along the A44 between Kington and Llangurig.
Fig. 16. Geologic sketch map of the area along the A44 between Rhayader and Aberystwyth.
Fig. 17. Ponterwyd. The Castell mine. Fractured rock invaded by mineral veins.
Fig. 18. The gorge at Devil’s Bridge.
Fig. 19. Parson's Bridge. The River Rheidol gorge with large potholes.
Fig. 20. Devil's Bridge. High moor plateau about 600 metres above sea level.
Fig. 21. Plynlimon, the highest mountain (752 metres) in central Wales.
Fig. 22. Geologic sketch map of the area along the A483.
Fig. 23. Newtown on the A483. Pencil slate in Silurian silt and mudstone.
Fig. 24. Geologic sketch map of the area along the A470 between Brecon and Newtown.
Fig. 25. The River Wye south of Builth Wells.
Fig. 26. Builth Wells. The bridge over the River Wye.
Fig. 27. Geologic sketch map of the area between Newtown and Dolgellau.
Fig. 28. Geologic sketch map of the area between Ffestiniog and Bala.
Fig. 29. The Arenig Hills northwest of Llyn Celyn.
Fig. 30. Geologic sketch map of the area along the B4391 from Bala to the intersection with the A495.
Fig. 31. Geologic sketch map of the Welsh borderland.
Fig. 32. Geologic sketch map of the Shrewsbury/Welshpool area.
Fig. 33. Middletown. Thick Ordovician volcanic ash beds.
Fig. 34. Geologic sketch map of the Welshpool/Church Stretton area.
Fig. 35. The Stiperstones.
Fig. 36. The stone stripes below the Stiperstone Ridge.
Chapter 5. Southeast Wales
Fig. 1. Geologic sketch map of southeast Wales.
Fig. 2. Geologic sketch map of the lower Usk valley and the Forest of Dean.
Fig. 3. Staunton, Forest of Dean. Old Red Sandstone conglomerate.
Fig. 4. Symonds Yat. The River Wye.
Fig. 5. Wyndcliff, north of Chepstow. Carboniferous Limestone with vertical joints.
Fig. 6. Geologic sketch map of the Valleys showing the eastern part of the Coalfield syncline.
Fig. 7. Geologic sketch map of the area between Cardiff and Brecon.
Fig. 8. Geologic cross section from Cardiff to Brecon
Fig. 9. Head of Rhondda valley, south of Hirwaun.
Fig. 10. The Brecon Beacons from Brecon.
Fig. 11. Quarry on the A40 north of the Brecon pass cut into thick beds of Devonian red sandstone.
Fig. 12. Ystradfellte. Millstone Grit, lying above ribs of Carboniferous Limestone.
Fig. 13. Ystradfellte Cave.
Fig. 14. Clydach Gorge, the A470 east of Brynmawr. Shale and sandstone of the Coal Measures.
Fig. 15. Black Rock Quarry. East of Brynmawr. Thick sandstone in the Coal Measures.
Fig. 16. Pontneddfechan. Dinas Rock, Craig-y-Dinas.
Fig. 17. Section across Dinas Rock showing the narrow band of rock affected by the Neath disturbance.
Fig. 18. Geologic sketch map of the western part of the Coalfield.
Fig. 19. Abercaf. Pennwyllt quarries.
Fig. 20. Pennwyllt quarries. Carboniferous Limestone with sea lily fossils, crinoids.
Fig. 21. Pennwyllt quarries. Millstone Grit.
Fig. 22. Henryd waterfall near Coelbren.
Fig. 23. A4069 south of Llangadog. Road cutting in Devonian Old Red Sandstone.
Fig. 24. Viewpoint on Black Mountain. The topmost layer of the Devonian Old Red Sandstone.
Fig. 25. Geologic sketch map of the area between Ross-on-Wye and Brecon.
Fig. 26. Ross-on-Wye. Road cutting in Devonian Old Red Sandstone.
Fig, 27. Abergavenny. Sugarloaf Mountain (327 219), capped by limestone overlying the top of the Old Red Sandstone.
Fig. 28. Abergavenny. Sketch of Blorenge Mountain.
Fig. 29. Geologic sketch map of the area between Brecon and Carmarthen.
Fig. 30. Geologic sketch map of the area along the M4.
Fig. 31. Geologic sketch map of the Glamorgan coast between Cardiff and Swansea.
Fig. 32. Lavernock Point. Jurassic limestone cliffs.
Fig. 33. Lavernock Point. Oyster fossils in Juurassic limestone.
Fig. 33. Barry Island. Triassic scree on an old erosion surface on Carboniferous Limestone.
Fig. 35. Llantwit Major. Wave-cut platform and cliff cut into Jurassic limestone.
Fig. 36. Southerndown. Jurassic limestone lying on Carboniferous Limestone.
Fig. 37. Southerndown. Sharp folds in banded Jurassic limestone against the massive Carboniferous Limestone.
Fig. 38. Geologic sketch map of the Gower.
Fig. 39. Three Cliffs Bay.
Fig. 40. Three Cliffs Bay. Carboniferous Limestone breccia.
Fig. 41. Rhossili Beach.
Fig. 42. Worms Head, southwest corner of the Gower.
Chapter 6. Southwest Wales
Fig. 1. Geologic sketch map of Southwest Wales.
Fig. 2. Geologic sketch map of the north coast of the St. David’s Peninsula.
Fig. 3. Llangrannog. Ordovician sand and mud contorted by submarine slides.
Fig. 4. Aberporth. Ordovician mudstone and thin layers of sandstone.
Fig. 5. The B4582 west of Cardigan. An Esker, the remains of a river that flowed on or within a glacier.
Fig. 6. Dinas Head. Glacial meltwater channel.
Fig. 7. Sketch map of the meltwater channels near Fishguard.
Fig. 8. Scleddau. Meltwater channel.
Fig. 9. Strumble Head, west of Fishguard. Massive Ordovician lava flows.
Fig. 10. Ordovician lavas. View east from near the Strumble Head lighthouse.
Fig. 11. Geologic sketch map of Abereiddy Bay.
Fig. 12. Abereiddy Bay. Ordovician volcanic ash beds alternating with softer slate.
Fig. 13. Geologic sketch map of the area from St. David’s to Carmarthen
Fig. 14. Geologic sketch map of St. David's Peninsula.
Fig. 15. Whitesand Bay. Cambrian sandstone with ripple marks.
Fig. 16. St. David's Head. Massive intrusive gabbros.
Fig. 17. Caerfai Bay. Cambrian sandstones in cliffs.
Fig. 18. Geologic sketch map and section across St. Bride's Bay between Newgale and Little Haven.
Fig. 19. Broad Haven. Faults and folds.
Fig. 20. Broadhaven. Fold in Coal Measures.
Fig. 21. Geologic sketch map of Pembroke and the Marloes Peninsula.
Fig. 22. Geologic sketch map of the Marloes Peninsula. Silurian rocks are thrust onto Devonian Old Red Sandstone.
Fig. 23. St. Bride's Haven. Horizontal Upper Carboniferous rocks on folded Silurian rocks on the foreshore.
Fig. 24. Sketch of Silurian sandstones beneath a 60-metre terrace that continues to Skomer Island.
Fig. 25. St. Martin's Haven. Silurian sandstone dips south toward Gateholm Island.
Fig. 26. Marloes Sands. Devonian Old Red Sandstone conglomerate near Gateholm Island.
Fig.27. Marloes Sands. Quartz veins in Devonian sandstone.
Fig. 28. St. Ann's Head. Devonian mudstone in cliffs.
Fig. 29. Geologic sketch map of the coastal region between Manorbier and St. Govan's Head.
Fig. 30. Stackpole Quay. Thick-bedded Carboniferous Limestone thrust over Devonian Old Red Sandstone beds.
Fig. 31. Geologic sketch map of west part of Pembroke peninsula.
Fig. 32. Geologic sketch map of Freshwater West.
Fig. 33. West Angle Bay. Thin-bedded Carboniferous Limestone lies on muddy limestone.
Fig. 34. Manorbier. Vertical sandstone and mudstone of the Old Red Sandstone.
Fig. 35. Geologic sketch map and cross section between Pendine and Penally.
Fig. 36. Saundersfoot. Anticlinal fold at Lady Cove.
Fig. 37. Amroth West. Coal Measure rocks.
Fig. 38. Amroth East. Coal Measures sequence in the cliffs.
Fig. 39. Pendine. Carboniferous Limestone in the cliffs.
Fig.
40. Pendine. Rubble breccia in collapsed cave in Carboniferous
Limestone.
Fig. 41. Geological sketch map of the area from Carmarthen to Fishguard
Fig. 42. Map of area between Carmarthen, the Llanstephan Peninsula and Pendine.
Fig. 43. Llanstephan. Red and green Old Red Sandstone rocks capped by a rubbly caliche.