List of geological faults of Wales

This is a list of the named geological faults affecting the rocks of Wales. See the main article on faults for a fuller treatment of fault types and nomenclature but in brief, the main types are normal faults, reverse faults, thrusts or thrust faults and strike-slip faults. Many faults may have acted as both normal faults at one time and as reverse or thrust faults at another and may or may not have also incorporated some degree of strike-slip movement too. Fault zones, fault belts and fault complexes typically describe assemblages of faults which have a common origin and history and whose alignments tend to be sub-parallel to one another.

There are also a number of 'disturbances', notably in South Wales. These linear features are a combination of faults and folds - the relative importance of faulting and folding varying along the length of each disturbance.

Key to tables

• Column 1 indicates the name of the fault. Note that different authors may use different names for the same fault or a section of it. Conversely the same name may be applied to more than one fault, particularly in the case of smaller faults which are widely separated. Names are as they appear in the literature and do not necessarily conform to the commonly accepted modern spelling or form of the place-names with which they are associated.
• Column 2 indicates the OS grid reference of the approximate midpoint of certain faults. Note that the mapped extent of a fault may not accurately reflect its actual extent.
• Column 3 indicates the county in which the fault occurs. Some traverse two or more counties of course.
• Column 4 indicates on which sheet, if any, of the British Geological Survey's 1:50,000 / 1" scale geological map series of England and Wales, the fault is shown and named (either on map/s or cross-section/s or both). Also listed are a handful of BGS maps at other scales, where the fault is both shown and named.
• Column 5 indicates a selection of publications in which references to the fault may be found. See references section for full details of publication.

Alphabetical lists of faults

A

Fault name	OS map ref	County	BGS map sheet	book references
Aber Dinlle Fault		Gwynedd		Brenchley & Rawson 2006
Aber Fault		Glamorganshire	E&W 248
Aber Richard Fault			E&W 194; 210
Aberbeeg Fault				Mem E&W 232
Aberdaron Fault		Gwynedd	E&W 133
Abergwesyn Fault			E&W 196, 212
Abertillery Fault			E&W 249	Mem E&W 232
Abertridwr Fault		Glamorganshire	E&W 249
Acorn Fault			E&W 230
Afon Banwy Fault		Powys	E&W 150
Afon Ganol Fault		Clwyd		Mem E&W 95/107
Afon Saint Fault		Gwynedd	E&W 133
Allt y Crib Fault			E&W 163
Allt y Grug Fault			E&W 230
Alyn Valley Fault			E&W 108
Anafon Fault		Gwynedd	E&W 106
Arthog - Caerdeon Fault			E&W 149
Axton Fault		Flintshire	E&W 96

B

Fault name	OS map ref	County	BGS map sheet	book references
Bala - Llanelidan Fault				Smith et al. 2005
Bala Fault			E&W 135; 136
Bala Fault Zone			UK (south) 625K
Beddgelert Fault		Gwynedd	E&W 119
Beech Hill Fault		Monmouthshire	Usk-Cwm:25K
Belmont Fault		Clwyd		Mem E&W 95/107
Benton Fault		Pembrokeshire	E&W 228	Brenchley & Rawson 2006
Berach Fault			E&W 230
Berw Fault		Anglesey		Brenchley & Rawson 2006
Berw Fault Complex		Anglesey		Brenchley & Rawson 2006
Bethel Fault		Glamorganshire	E&W 247
Bettws Fault			E&W 230
Bettws Newydd Fault				Mem E&W 232
Blaenavon Fault		Monmouthshire	E&W 232
Blaenhirwaun Thrust			E&W 230
Blaen Onneu Fault			E&W 232
Bodafon Thrust		Anglesey		Brenchley & Rawson 2006
Bodelwyddan Fault		Denbighshire	E&W 95; 107	Mem E&W 95/107
Box Fault		Glamorganshire	E&W 247
Bristol Channel Fault Zone		Bristol Channel
Bronnant Fault		Ceredigion	E&W 178; 210; 211
Bronnant Fault Zone		Ceredigion	E&W 194; 195
Brothers Fault		Glamorganshire	E&W 247
Brwynd Overthrust			E&W 163
Bryn Eglwys Fault			E&W 120	Brenchley & Rawson 2006
Bryn Morgan Thrust			E&W 230
Bryn Posteg Fault			E&W 164
Bryn Rhys Fault		Clwyd		Mem E&W 95/107
Brynderi Fault		Monmouthshire		Mem E&W 233/250
Bryneglwys Fault			E&W 121
Bryngwili Fault			E&W 230
Bryngwyn Fault		Glamorganshire	E&W 230; 247
Bryn-y-maen Fault		Denbighshire	E&W 95
Bwlchgwyn Fault			E&W 108
Bylchau Fault		Denbighshire	E&W 107	Mem E&W 95/107

C

Fault name	OS map ref	County	BGS map sheet	book references
Cae Parc Fault		Glamorganshire	E&W 247
Caerdeon Bodlyn Fault		Merionethshire	E&W 135
Caergwrle Fault			E&W 108
Caerleon Fault		Monmouthshire	E&W 249; Usk-Cwm:25K
Caerphilly Fault		Glamorganshire	E&W 249
Camdwr Fault			E&W 163
Capel Garmon Fault		Clwyd	E&W 107	Mem E&W 95/107
Cardigan - Fishguard Fault Belt		Pembrokeshire	E&W 210
Carmel Fault (Powys)		Powys	E&W 179
Carmel Fault (Carmarthenshire)		Carmarthenshire	E&W 230
Carmel Head Thrust			UK (south) 625K	Brenchley & Rawson 2006
Carreg Maen Taro Fault			E&W 232
Carrog Valley Fault		Ceredigion	E&W 178
Cascade Overthrust			E&W 163
Castell Fault			E&W 163	Mem E&W 165/151
Cefn Fault		Clwyd		Mem E&W 95/107
Cefncynfal Fault		Powys		Mem E&W 165/1051
Cefn Bryn Thrust		Glamorganshire	E&W 246
Cefn Crib Fault		Glamorganshire	E&W 249
Cefn Fault			E&W 107
Cefn Garw Fault		Monmouthshire		Mem E&W 233/250
Cefn Ila Fault		Monmouthshire	Usk-Cwm:25K	E&W 232
Cefnamwlch-Rhiw Fault		Gwynedd	E&W 134
Ceibwr Bay Fault			E&W 193
Ceidio Fault		Anglesey		Brenchley & Rawson 2006
Ceunant Fault			E&W 149
Chapel Fault			E&W 231
Chepstow Fault		Monmouthshire		Mem E&W 233/250
Church Stretton Fault System				Brenchley & Rawson 2006
Church Stretton Fault Zone			E&W 213	Mem E&W 165/151
Cilfeigan Fault		Monmouthshire	E&W 249; Usk-Cwm:25K
Claerwen Fault			E&W 179
Clochaenog Fault		Clwyd		Mem E&W 95/107
Clwyd Fault				Smith et al. 2005
Clydach Bridge Fault		Monmouthshire	E&W 232
Clywedog Fault			E&W 164
Clytha Fault			E&W 232
Coalbrook Fault			E&W 230
Coed Hir Fault			E&W 231
Coed Ithel Fault		Monmouthshire		Mem E&W 233/250
Coedycerrig Fault			E&W 232
Coed-y-paen Fault		Monmouthshire	E&W 249; Usk-Cwm:25K
Conwy Valley Fault/Conway Valley Fault		Gwynedd	E&W 106	Mem E&W 95/107
Copper Works Fault		Glamorganshire	E&W 247
Cors-bol Fault		Anglesey		Brenchley & Rawson 2006
Craig Twrch Fault			E&W 212
Craiglaseithin Fault		Gwynedd	E&W 135/149
Craignant - Milton Fault				Smith et al. 2005
Craignant Fault				Smith et al. 2005
Craig-y-beri Fault			E&W 137
Craig-y-glyn Fault			E&W 137
Creigydd Fault		Monmouthshire	E&W 249; Usk-Cwm:25K
Cribarth Fault			E&W 213
Crick Fault		Monmouthshire		Mem E&W 233/250
Cross Ash Fault		Monmouthshire		Mem E&W 233/250
Crychan Fault		Powys	E&W 196, 213
Crychan Fault Belt			E&W 213
Cwm Cayo Brook Fault		Monmouthshire		Mem E&W 233/250
Cwm Cynnen Fault			E&W 211
Cwm Dockin Fault			E&W 165
Cwm Dwfnant Fault			E&W 196
Cwm Earl Fault			E&W 165
Cwm Felin Fault		Glamorganshire	E&W 247
Cwm Llwyd Fault			E&W 230
Cwm Pennant Fault				Brenchley & Rawson 2006
Cwm Pit Fault		Glamorganshire	E&W 247
Cwm Sylwi Fault			E&W 149; 163
Cwmcarvan Fault		Monmouthshire		Mem E&W 233/250
Cwmdockin Fault		Powys		Mem E&W 151/165
Cwm-dows Fault		Glamorganshire	E&W 249
Cwmgwineu Fault		Glamorganshire	E&W 247
Cwmllynfell Fault			E&W 230
Cwm-Mawr Fault			E&W 196
Cwmmawr Thrust			E&W 230
Cwmneol Faul			E&W 231
Cymmer Fault		Glamorganshire	E&W 248
Cynheidre Thrust			E&W 230
Cynllaith Fault			E&W 137

D

Fault name	OS map ref	County	BGS map sheet	book references
Daren Ddu Fault		Glamorganshire	E&W 249
Daron Fault		Gwynedd	E&W 133
Denbigh Fault		Clwyd	E&W 107	Mem E&W 95/107
Dinas Fault (Powys)		Powys	E&W 231
Dinas Fault (Glams)		Glamorganshire	E&W 248
Dinorwic Fault		Gwynedd	E&W 106
Dip Fach Fault			E&W 231
Dolforwyn Fault			E&W 165	Mem E&W 151/165
Dolwar Fault		Powys	E&W 150
Dowlais Fault (Mons)		Monmouthshire	E&W 231; 232
Dowlais Fault (Glams)		Glamorganshire	E&W 249
Duffryn Fault		Glamorganshire	E&W 230, 247
Dulas Fault			E&W 196
Dulas Gap Fault		Denbighshire	E&W 95; 107	Mem E&W 95/107
Dyffryn Maelor Fault		Clwyd		Mem E&W 95/107
Dyfi Valley Fault		Powys	E&W 150
Dyfnant Fault		Powys	E&W 150
Dyfngwm Fault			E&W 164
Dylife Esgairgaled Fault			E&W 164
Dylife Fault			E&W 164
Dynant Fault			E&W 230
Dysynni Fault			E&W 149
Dyto Fault		Clwyd		Mem E&W 95/107

E

Fault name	OS map ref	County	BGS map sheet	book references
East Llangerniew Fault		Clwyd	E&W 107	Mem E&W 95/107
Efailnewydd Fault		Gwynedd	E&W 134
Eglwysbach Fault		Clwyd		Mem E&W 95/107
Energlyn Fault		Glamorganshire	E&W 249
Erroxhill Fault		Pembrokeshire	E&W 228

F

Fault name	OS map ref	County	BGS map sheet	book references
Felin Arw Fault		Glamorganshire	E&W 248
Ferry Fault		Glamorganshire	E&W 247
Flint Fault			E&W 108
Forge Overthrust			E&W 149; 163

G

Fault name	OS map ref	County	BGS map sheet	book references
Gadlys Fault		Glamorganshire	E&W 231; 248
Gardeners Fault		Glamorganshire	E&W 230; 247
Garth - Llanwrtyd Fault Belt			E&W 212
Garth Fault			E&W 196, 213
Garth Ferry Fault		Anglesey		Brenchley & Rawson 2006
Garth Hill Overthrust		Glamorganshire	E&W 249
Gelli Fault		Glamorganshire	E&W 249
Gelligaer Fault		Glamorganshire	E&W 249
Gelli-goch Overthrust			E&W 149; 163
Giant's Grave Fault		Glamorganshire	E&W 247
Glan Hafren Fault			E&W 165	Mem E&W 151/165
Glanalders Fault			E&W 179
Glandyfi Fault			E&W 163
Glaslyn Valley Fault				Brenchley & Rawson 2006
Glyn Ceiriog Fault			E&W 121
Glyn Fault		Monmouthshire	E&W 249; Usk-Cwm:25K
Glyn Valley Fault			E&W 135
Glyn Wallis Fault			E&W 230
Glyncorrwg Fault		Glamorganshire	E&W 231; 248
Gnoll Fault		Glamorganshire	E&W 247
Gop Fault		Flintshire	E&W 95	Mem E&W 95/107
Gors Fault		Glamorganshire	E&W 230, 247
Gorsedd Bran Fault		Clwyd		Mem E&W 95/107
Gorseinon Fault		Glamorganshire	E&W 247
Great Ewloe Fault			E&W 108
Greenland Fault		Monmouthshire	E&W 232
Gresford Fault			E&W 121
Grib Fault			E&W 230
Groes Fault		Clwyd	E&W 107	Mem E&W 95/107
Grovesend Fault		Glamorganshire	E&W 230; 247
Guilsfield Fault		Powys	E&W 150, 151	Mem E&W 151/165
Gwaynynog Fault		Clwyd	E&W 107	Mem E&W 95/107
Gwern-ddu Fault		Monmouthshire		Mem E&W 233/250
Gwespyr Fault		Flintshire	E&W 96
Gwili Fault		Glamorganshire	E&W 230, 247
Gwrych Castle Fault		Denbighshire	E&W 95; 107	Mem E&W 95/107
Gyrnos Fault			E&W 231

H

Fault name	OS map ref	County	BGS map sheet	book references
Hafan Fault			E&W 163
Hawarden Fault			E&W 108
Hendre Fault			E&W 230
Highgate Fault		Powys	E&W 164; 165	Mem E&W 151/165
Hirwaun No 1 Fault			E&W 231
Hirwaun No 2 Fault			E&W 231
Hirwaun No 2a Fault			E&W 231
Hirwaun No 3 Fault			E&W 231
Hudnalls Fault		Monmouthshire		Mem E&W 233/250

I,J,K

Fault name	OS map ref	County	BGS map sheet	book references
Itton Fault		Monmouthshire		Mem E&W 233/250
John Grey's Fault		Glamorganshire	E&W 247
Keepers Lodge Fault			E&W 230
Kilkenny Fault		Glamorganshire	E&W 231; 249
King's Wood Fault		Monmouthshire		Mem E&W 233/250
Kinmel Park Fault		Denbighshire	E&W 95	Mem E&W 95/107

L

Fault name	OS map ref	County	BGS map sheet	book references
Leeswood Fault			E&W 108
Little Mill Fault			E&W 232
Llanbadoc Fault		Monmouthshire	E&W 232; Usk-Cwm:25K
Llancayo Fault		Monmouthshire	E&W 233	Mem E&W 233/250
Llandrindod - Pen-y-waun Fault Belt			E&W 213
Llandyfan Fault			E&W 230
Llandynan Fault			E&W 121
Llanegryn Fault			E&W 149
Llanelidan Fault			E&W 121
Llanerchyraur Fault			E&W 164
Llanerfyl Fault		Powys	E&W 150
Llanfabon Fault		Glamorganshire	E&W 231; 249
Llanfrechfa Fault		Monmouthshire	E&W 249; Usk-Cwm:25K
Llangattock Fault				Mem E&W 233/250
Llanglydwen Fault			E&W 210; 211
Llangollen - Llantysilio - Aqueduct Fault				Smith et al. 2005
Llangollen Fault			E&W 121
Llangwm Fault		Monmouthshire		Mem E&W 233/250
Llangynidr Fault				Mem E&W 232
Llanhilleth Fault		Glamorganshire	E&W 249
Llannefydd Fault		Clwyd	E&W 107	Mem E&W 95/107
Llanrhaeadr Fault		Clwyd	E&W 107	Mem E&W 95/107
Llantysilio Fault			E&W 121
Llanvair Discoed Fault		Monmouthshire		Mem E&W 233/250
Llanvair Fault		Monmouthshire	E&W 250
Llanvapley Fault				Mem E&W 232
Llanvihangel Fault		Monmouthshire		Mem E&W 233/250
Llanwonno Fault		Glamorganshire	E&W 248
Llanwrtyd Fault			E&W 196
Llanwrtyd Fault			E&W 213
Llechwedd Fault			E&W 164
Llethir Fault			E&W 230
Llety Wilws Fault			E&W 230
Llwyn Celyn Fault			E&W 230
Llwyn Fault			E&W 165
Llyfnant Fault			E&W 163
Llysfaen Fault		Denbighshire	E&W 95	Mem E&W 95/107
Longoaks Fault		Glamorganshire	E&W 247
Lunnon Fault		Glamorganshire	E&W 247

M

Fault name	OS map ref	County	BGS map sheet	book references
Maen Fault		Clwyd		Mem E&W 95/107
Maes-gwyn (or Maes Gwyn) Fault		Clwyd	E&W 107	Mem E&W 95/107
Marian Ffrith (or Marianffrith) Fault		Flintshire	E&W 95	Mem E&W 95/107
Mathern Fault		Monmouthshire		Mem E&W 233/250
Mawddach Fault			E&W 149
Melai Fault		Clwyd		Mem E&W 95/107
Menai Strait Fault System				Brenchley & Rawson 2006
Merthyr Church Fault		Glamorganshire	E&W 231; 249
Meusydd Fault			E&W 230
Minera Fault Belt			E&W 121
Minffordd Fault				Brenchley & Rawson 2006
Mochras Fault		Merionethshire	E&W 135; 49	Brenchley & Rawson 2006
Moelfre Fault		Merionethshire	E&W 135
Moel-Gilau Fault		Glamorganshire	E&W 248
Montgomery Fault		Powys		Mem E&W 151/165
Morfa Fault		Glamorganshire	E&W 247, 248
Morlais Fault		Glamorganshire	E&W 247
Mount Pleasant Fault			E&W 230
Mynydd Bach Fault			E&W 195
Mynydd Bodrochwyn Fault		Clwyd		Mem E&W 95/107

N

Fault name	OS map ref	County	BGS map sheet	book references
Nant Cerrig Fault		Clwyd		Mem E&W 95/107
Nant Dyar Fault				Mem E&W 232
Nant Marl Fault			E&W 230
Nant y Fedw Fault			E&W 196
Nant-Figillt Fault			E&W 108
Nantmor Fault		Gwynedd	E&W 119
Nantygwrdy Fault			E&W 164
Nantyricket Fault			E&W 164
Nedern Fault		Monmouthshire		Mem E&W 233/250
Nercwys - Nant-Figillt Fault Zone			E&W 108
New House Thrust			E&W 165
Newcastle Fault		Monmouthshire		Mem E&W 233/250
Newlands Thrust		Glamorganshire	E&W 247, 248
Newmarket Fault		Clwyd		Mem E&W 95/107
Newton Fault		Glamorganshire	E&W 247
Newmarket Fault		Flintshire	E&W 95
Newport Sands Fault			E&W 193; 210
Nicholaston Fault		Glamorganshire	E&W 247

O

Fault name	OS map ref	County	BGS map sheet	book references
Ochr-y-cefn Fault		Clwyd		Mem E&W 95/107
Ogof Cadno Fault			E&W 193
Ogof Fault			E&W 163
Olway Brook Fault		Monmouthshire		Mem E&W 233/250

P,Q

Fault name	OS map ref	County	BGS map sheet	book references
Palleg Fault			E&W 230
Palmer's Lake Overthrusts		Pembrokeshire	E&W 244/5
Pant Fault		Denbighshire	E&W 95	Mem E&W 95/107
Pant-y-fotty Fault		Clwyd		Mem E&W 95/107
Paper Mill Fault			E&W 108
Parc Postyn Fault		Clwyd		Mem E&W 95/107
Pared Fault		Gwynedd	E&W 133
Parwyd Fault		Gwynedd	E&W 133
Pendaren Fault		Glamorganshire	E&W 249
Penffordd Fault		Pembrokeshire	E&W 210
Pengam Fault		Glamorganshire	E&W 249
Pennal Fault			E&W 149; 150; 163
Penrhiwfelen Fault		Glamorganshire	E&W 247
Penterry Fault		Monmouthshire		Mem E&W 233/250
Pentre Clwydau Fault			E&W 231
Pentre Felin Fault		Clwyd		Mem E&W 95/107
Pentre Llanharan Thrust		Glamorganshire	E&W 248
Pentremawr Lag Fault		Carmarthenshire	E&W 229
Pentre Tafarn-y-fedw Fault		Clwyd		Mem E&W 95/107
Pentwyn Fault (Mons)		Monmouthshire	E&W 249
Pentwyn Fault (Glams)		Glamorganshire	E&W 249
Pen-y-castell Fault		Glamorganshire	E&W 231, 248
Penydarren Fault			E&W 231
Pen-y-Fan Fault		Monmouthshire	E&W 232
Pen-y-llan Fault		Monmouthshire	E&W 249; Usk-Cwm:25K
Pen-y-parc Fault		Monmouthshire	E&W 249; Usk-Cwm:25K
Plas Isaf Fault		Glamorganshire	E&W 247
Pont Morlais Fault			E&W 230
Pontarsais Fault			E&W 212
Pont-y-ddol Fault		Clwyd		Mem E&W 95/107
Pontypool Road Fault		Monmouthshire	E&W 232
Port Eynon Thrust		Glamorganshire	E&W 246
Portskewett Hill Fault				Mem E&W 233/250
Prestatyn Fault		Clwyd	E&W 95	Mem E&W 95/107
Pwllau Bach Fault			E&W 231
Pwllmawr Fault		Glamorganshire	E&W 247
Pwll-meyric Fault		Monmouthshire		Mem E&W 233/250

R

Fault name	OS map ref	County	BGS map sheet	book references
Ramsey Fault		Pembrokeshire	E&W 209
Rassau Fault				Mem E&W 232
Reservoir Fault		Monmouthshire		Mem E&W 233/250
Rhadyr Fault		Monmouthshire	Usk-Cwm:25K	Mem E&W 232
Rhaiadr Fault			E&W 137
Rhiw Fault		Glamorganshire	E&W 249
Rhiw Gwraidd Fault			E&W 179
Rhobell Fracture				Brenchley & Rawson 2006
Rhos Fault		Glamorganshire	E&W 231; 232; 249
Rhuallt Fault		Flintshire	E&W 95	Mem E&W 95/107
Rhydding Fault		Glamorganshire	E&W 230; 247
Rhyd Sion Wynn Fault		Clwyd		Mem E&W 95/107
Rhyd-y-creua Fault		Clwyd		Mem E&W 95/107
Rhymney Fault				Mem E&W 232
Ritec Fault		Pembrokeshire		Brenchley & Rawson 2006
Road Uchaf Fault?				Brenchley & Rawson 2006
Rock Park Fault			E&W 196
Rockfield Fault		Monmouthshire		Mem E&W 233/250

S

Fault name	OS map ref	County	BGS map sheet	book references
Sarn-Abersoch Thrust		Gwynedd	E&W 134
Sawdde Fault			E&W 212
Severn Valley Fault Belt			E&W 151	Toghill P. 2006
Siamber Wen Fault		Denbighshire	E&W 95; 107	Mem E&W 95/107
Sirhowy Fault		Monmouthshire	E&W 232
Six Pit Fault		Glamorganshire	E&W 247
Soflen Fault		Clwyd	E&W 107	Mem E&W 95/107
Soughton Fault			E&W 108
St Arvans Fault		Monmouthshire		Mem E&W 233/250
St Brides Fault		Monmouthshire		Mem E&W 233/250
Stradey Fault		Carmarthenshire	E&W 229
Strumble Head Fault		Pembrokeshire	E&W 210
Swansea Fault		Glamorganshire	E&W 247
Swansea Valley Fault			E&W 213
Syddyn Fault		Carmarthenshire	E&W 229

T

Fault name	OS map ref	County	BGS map sheet	book references
Tafalog Fault		Powys	E&W 150
Taipellaf Fault		Clwyd		Mem E&W 95/107
Talgarth Fault		Monmouthshire		Mem E&W 233/250
Tal-y-coed Fault		Monmouthshire		Mem E&W 233/250
Tal-y-llyn Fault			E&W 149
Tanant Fault			E&W 137
Teifi Fault			E&W 212
Tintern Fault		Monmouthshire		Mem E&W 233/250
Tirdonkin Fault		Glamorganshire	E&W 247
Tonfannau Fault			E&W 149
Trafle Fault		Glamorganshire	E&W 247
Trawsfynydd - Cwm Bowyd Fault				Brenchley & Rawson 2006
Trawsfynydd Fault			MW&M:250K, E&W 135
Tredegar Fault		Monmouthshire	E&W 231; 232
Tre-fal-du Fault		Monmouthshire		Mem E&W 233/250
Trelleck Common Fault		Monmouthshire		Mem E&W 233/250
Trelleck Fault		Monmouthshire		Mem E&W 233/250
Tremadog Thrust Zone				Brenchley & Rawson 2006
Tre-'r-ddol Fault			E&W 163
Trevethin Fault		Glamorganshire, Monmouthshire	E&W 232; 249
Trinant Fault		Glamorganshire	E&W 249
Tumble Fault			E&W 230
Tweedle Fault			E&W 231
Twrch Fechan Fault			E&W 230
Twyn Sych Fault			E&W 231
Ty Llwyd Fault			E&W 230
Ty Mawr Fault		Clwyd		Mem E&W 95/107
Tyn-y-caeau Fault (Denb)		Denbighshire	E&W 95	Mem E&W 95/107
Ty'n-y-caeau Fault (Mons)		Monmouthshire	E&W 249; Usk-Cwm:25K

U,V

Fault name	OS map ref	County	BGS map sheet	book references
Upper Artro Fault		Merionethshire	E&W 135
Usk Fault		Monmouthshire		Mem E&W 233/250
Vale of Clwyd Fault		Denbighshire	E&W 121; 95	Mem E&W 95/107
Van Fault			E&W 164

W,X,Y,Z

Fault name	OS map ref	County	BGS map sheet	book references
Warren Fault			E&W 230
Welsh Borderland Fault				Smith et al. 2005
Welsh Borderland Fault System			UK (south) 625K	Brenchley & Rawson 2006
Wenallt Fault			E&W 164
Werf Fault			E&W 231
West Llangerniew Fault		Clwyd	E&W 107	Mem E&W 95/107
Weston Madoc Fault			E&W 165
Wonastow Fault		Monmouthshire		Mem E&W 233/250
Wrexham Fault			E&W 121
Yspytty Ifan Fault			E&W 120
Ystwyth Fault			E&W 179	Mem E&W 151/165

List of Disturbances

The following named features comprise both faulting and folding;

table of named disturbances

Disturbance name	OS map ref	County	BGS map sheet	book references
Caerbryn Disturbance		Carmarthenshire	E&W 230
Carreg Cennen Disturbance		Carmarthenshire	E&W 230
Clun Forest Disturbance
Cribarth Disturbance		Powys	E&W 230, 231
Llandyfaelog Disturbance		Carmarthenshire	E&W 231
Llannon (or Llanon) Disturbance		Carmarthenshire	E&W 230
Neath Disturbance			E&W 231
Pontyclerc Disturbance		Carmarthenshire	E&W 230
Saron Disturbance		Carmarthenshire	E&W 230
Trimsaran Disturbance

See also

• List of geological faults of England
• List of geological faults of Northern Ireland
• List of geological faults of Scotland
• List of geological folds in Great Britain
• Geological structure of Great Britain

References

Maps

• 1:625,000 scale geological map 2007, Bedrock Geology UK South, British Geological Survey, Keyworth, Notts (UK (south) 625K)
• 1:250,000 scale geological map Mid Wales and the Marches, British Geological Survey, Keyworth, Notts (MW & M 250K)
• various of 1:50,000 scale geological maps of England and Wales, British Geological Survey, Keyworth, Notts (E & W no.)
• 1:25,000 scale sheet Usk - Cwmbran in Classic Areas of British Geology series, British Geological Survey, Keyworth, Notts (Usk-Cwm: 25K)

Books

• Barclay, W.J. 1989 Geology of the South Wales Coalfield Part II, the country around Abergavenny, 3rd edition. Mem Br. Geol. Surv. sheet 232 (England and Wales) (Mem E&W 232)
• Brenchley, PJ & Rawson, PF (eds) 2006. The Geology of England and Wales, (2nd edn) The Geological Society, London (Brenchley & Rawson 2006)
• Cave, R. & Hains, B.A, 2001 Geology of the country around Montgomery and the Ordovician rocks of the Shelve area Memoir of the British Geological Survey. Sheet 165 with part of sheet 151 (Welshpool) (England and Wales).(Mem E&W 165/151)
• Smith et al. 2005 Structure & Evolution of the south-west Pennine Basin and adjacent area. Subsurface memoir of the British Geological Survey. (Smith et al. 2005)
• Toghill, P 2006 Geology of Shropshire (2nd edn) Crowood Press, Wilts (Toghill P 2006)
• Warren et al. 1984, Geology of the country around Rhyl and Denbigh, Mem Br Geol Svy, sheets 95 and 107 (Mem E&W 95/107)
• Welch, FBA & Trotter, FM 1961 Geology of the Country around Monmouth and Chepstow, HMSO (explanation of 1" geol. sheets 233 & 250 (England and Wales) (Welch, FBA & Trotter, FM 1961)