List of geological groups of Great Britain
This is a sortable list of the groups into which the rock succession of Great Britain and surrounding seas is formally divided. Rock sequences are described by geologists by dividing them hierarchically thus: individual 'beds' of rock (or in the case of certain volcanic rocks, 'flows') are grouped into 'members', members are grouped into 'formations', formations into 'groups' and groups occasionally into 'supergroups'. Some groups are also subdivided into 'subgroups'. Not all of these hierarchical layers are necessarily present or defined within a particular rock succession. Many of these groups will be encountered as 'series' in older geological literature or indeed simply as the proper name e.g. 'Dalradian' or 'Millstone Grit' though care needs to be exercised as many of the names have or have had other meanings which may not coincide with the assemblage of rocks referred to formally through designation as a 'group'.
With all such stratigraphical terms as 'groups', 'formations' and 'members' it is standard practice to capitalise both the proper name and the 'term-word' as per the recommendation of the International Commission on Stratigraphy e.g. Wentnor Group and not Wentnor group .[ 1]
Notes:
Column 1 indicates the name of the geological group. Those marked with an asterisk are no longer formally recognised but are included as they occur widely in literature.
Column 2 indicates during which geological period the rocks of each group were deposited. Note that where more than one period is indicated deposition stretched across the period boundary in at least a part of the group's geographical extent but not necessarily across the whole of its extent.
Column 3 permits sorting by period in chronological order ie Quaternary Period is 01; Neogene ,03; Palaeogene ,05; Cretaceous ,07; Jurassic ,09 Triassic ,11; Permian ,13; Carboniferous ,15; Devonian ,17; Silurian ,19; Ordovician ,21; Cambrian ,23; Ediacaran ,25; Cryogenian ,27; Tonian ,29; Stenian , 31; and Ectasian , 33 - the last five being some of the periods into which the Proterozoic Eon is divided.
Column 4 indicates in which of the three nations of Great Britain , the group is known to occur, followed by which of the surrounding sea areas (if any), including specifically: Atlantic Ocean , Celtic Sea , English Channel , Irish Sea , North Sea . (At present, for the purposes of this table 'Celtic Sea' also includes the Bristol Channel whilst 'Atlantic Ocean' includes all sea areas off the west coast of Scotland.) Note that the Isle of Man is not a part of Great Britain but is included here for convenience.
Group
Period
Period sequence
Country/sea area
Aberystwyth Grits Group
Silurian
19
Wales
Albion Glacigenic Group
Quaternary
01
England, Scotland, Celtic Sea
Ancholme Group
Jurassic
09
England
Appin Group
Cryogenian
27
Scotland
Appleby Group
Permian
13
England, Scotland
Aran Volcanic Group
Ordovician
21
Wales
Arbuthnott Group *
Devonian
17
Scotland
Arbuthnott-Garvock Group
Devonian
17
Scotland
Ardmillan Group
Ordovician
21
Scotland
Ardvreck Group
Cambrian
23
Scotland
Arfon Group
Ediacaran
25
Wales
Argyll Group
Ediacaran
25
Scotland
Avon Group
Carboniferous
15
England, Wales
Aylesbeare Group *
Triassic
11
England
Aylesbeare Mudstone Group
Triassic
11
England
Bacton Group
Triassic
11
North Sea
Badenoch Group
Tonian
29
Scotland
Balcreuchan Group
Cambrian/Ordovician
22
Scotland
Banks Group
Jurassic
09
North Sea
Barr Group
Ordovician
21
Scotland
Barton Group
Palaeogene
05
England
Bathgate Group
Carboniferous
15
Scotland
Benton Volcanic Group
Cryogenian
27
Wales
Bisat Group
Carboniferous
15
Irish Sea
Blackbrook Group
Ediacaran
25
England
Border Group
Carboniferous
15
England, Scotland
Borrowdale Volcanic Group
Ordovician
21
England
Bowland High Group
Carboniferous
15
England
Bracklesham Group
Palaeogene
05
England
Brand Group
Cambrian
23
England
Brent Group
Jurassic
09
North Sea
Britannia Catchments Group
Palaeogene/Neogene/Quaternary
04
England, Scotland, Wales, Irish Sea
British Coastal Deposits Group
Quaternary
01
England, Scotland, Wales, Irish Sea
Builth Volcanic Group
Ordovician
21
Wales
Caerbwdy Group
Ediacaran
25
Wales
Caerfai Group
Cambrian
23
Wales
Caithness Flagstone Group
Devonian
17
Scotland
Caledonia Glacigenic Group
Quaternary
01
England, Scotland, Wales, Irish Sea
Cementstone Group *
Carboniferous
15
Scotland
Chalk Group
Cretaceous
07
England, Atlantic Ocean, North Sea
Clackmannan Group
Carboniferous
15
Scotland
Claerwen Group
Silurian
19
Wales
Clair Group
Devonian/Carboniferous
16
Atlantic
Clwyd Limestone Group
Carboniferous
15
Wales
Coniston Group
Silurian
19
England
Conybeare Group
Carboniferous
15
North Sea
Corallian Group
Jurassic
09
England
Cosheston Group
Devonian
17
Wales
Crag Group
Neogene/Quaternary
02
England
Craven Group
Carboniferous
15
England, Isle of Man
Crawford Group
Ordovician
21
Scotland
Cromer Knoll Group
Cretaceous
07
England, Scotland, Atlantic Ocean, North Sea
Cumbrian Coast Group
Permian
13
England, Scotland, Irish Sea
Cwmystwyth Grits Group
Silurian
19
Wales
Dalby Group
Silurian
19
Isle of Man
Dartmouth Group
Devonian
17
England
Dent Group
Ordovician
21
England
Drefach Group
Ordovician
21
Wales
Dungavel Group
Silurian
19
Scotland
Dunlin Group
Jurassic
09
North Sea
Dunnottar-Crawton Group
Silurian/Devonian
18
Scotland
Dunrobin Bay Group
Jurassic
09
North Sea
Dunwich Group
Quaternary
01
England
Durness Group
Cambrian/Ordovician
22
Scotland
Eday Group
Devonian
17
Scotland
Eriboll Group [ 2]
Cambrian
23
Scotland
Exeter Group
Permian
13
England
Exmoor Group
Devonian/Carboniferous
16
England
Eycott Group *
Ordovician
21
England
Eycott Volcanic Group
Ordovician
21
England
Faroe Group
Palaeogene
05
Atlantic Ocean
Farne Group
Carboniferous
15
North Sea
Fishguard Volcanic Group
Ordovician
21
Wales
Fladen Group
Jurassic
09
North Sea
Forres Sandstone Group
Devonian
17
Scotland
Gala Group
Silurian
19
Scotland
Garvock Group *
Devonian
17
Scotland
Garwood Group
Carboniferous
15
Irish Sea
Girvan Group
Silurian
19
Scotland
Glenbuck Group
Silurian
19
Scotland
Glenfinnan Group
Tonian
29
Scotland
Grampian Group
Cryogenian
27
Scotland
Gray Sandstone Group
Silurian
19
Wales
Great Estuarine Group
Jurassic
09
Scotland
Great Oolite Group
Jurassic
09
England, English Channel
Great Scar Limestone Group
Carboniferous
15
England, Isle of Man
Gwna Group
Ediacaran/Cambrian
24
Wales
Hagshaw Group
Silurian
19
Scotland
Haisborough Group
Triassic
11
North Sea
Harlech Grits Group
Cambrian
23
Wales
Hawick Group
Silurian
19
Scotland
Heron Group
Triassic
11
North Sea
Holsworthy Group
Carboniferous
15
England
Humber Group
Jurassic/Cretaceous
08
Scotland, Atlantic Ocean, North Sea
Inferior Oolite Group
Jurassic
09
England, Irish Sea, English Channel
Ingleton Group
Ordovician
21
England
Inner Hebrides Group
Cretaceous
07
Scotland
Inverclyde Group
Carboniferous
15
Scotland
Inverness Sandstone Group
Devonian
17
Scotland
Kendal Group
Silurian
19
England
Kidston Group
Carboniferous
15
Irish Sea, Celtic Sea
Kyle Group
Devonian
17
North Sea
Lambeth Group
Palaeogene
05
England
Lanark Group
Silurian/Devonian
18
Scotland
Lias Group
Triassic/Jurassic
10
England, Wales, Celtic Sea, English Channel, Irish Sea, North Sea
Llanbedrog Volcanic Group
Ordovician
21
Wales
Llewelyn Volcanic Group
Ordovician
21
Wales
Loch Maree Group
Palaeoproterozoic
33
Scotland
Locheil Group
Tonian
29
Scotland
Lower Greensand Group
Cretaceous
07
England, English Channel
Lower Old Red Group
Devonian
17
North Sea
Lower Old Red Sandstone Group
Silurian/Devonian
18
England, Scotland, Wales
Manx Group
Cambrian
23
Isle of Man
Maplewell Group
Ediacaran
25
England
Marros Group
Carboniferous
15
England, Wales
Mawddach Group
Cambrian
23
Wales
Meadfoot Group
Devonian
17
England
Menevian Group
Cambrian
23
Wales
Mercia Mudstone Group
Triassic
11
England, Scotland
Middle Old Red Group
Devonian
17
North Sea
Milford Haven Group
Silurian/Devonian
18
Wales
Millstone Grit Group
Carboniferous
15
England, Isle of Man
Moffat Shale Group
Ordovician/Silurian
20
Scotland
Monks Water Group
Silurian
19
Scotland
Montrose Group
Palaeogene
05
North Sea
Morar Group
Stenian/Tonian
30
Scotland
Moray Group
Palaeogene
05
Atlantic Ocean, North Sea
Mull Lava Group
Palaeogene
05
Scotland
Nordland Group
Neogene/Quaternary
02
Atlantic Ocean, North Sea
North Esk Group
Silurian
19
Scotland
Ogofgolchfa Group
Ediacaran
25
Wales
Ogwen Group
Ordovician
21
Wales
Papa Group
Triassic
11
Atlantic Ocean
Peak Limestone Group
Carboniferous
15
England
Peel Sandstone Group
Devonian
17
Isle of Man
Pembroke Limestone Group
Carboniferous
15
England, Wales
Penarth Group
Triassic/Jurassic
10
England, Wales, Scotland, Irish Sea, English Channel, North Sea
Pennine Coal Measures Group
Carboniferous
15
England, Isle of Man, Scotland, Wales
Penrhiw Group
Cryogenian/Ediacaran
26
Wales
Portland Group
Jurassic
09
England, English Channel
Priesthill Group
Silurian
19
Scotland
Purbeck Group
Jurassic/Cretaceous
08
England, English Channel
Ramsey Sound Group
Ediacaran
25
Wales
Ravenscar Group
Jurassic
09
England
Ravenstonedale Group
Carboniferous
15
England, Isle of Man
Red Marl Group
Silurian/Devonian
18
England, Wales
Residual Deposits Group
Palaeogene/Neogene/Quaternary
03
England
Reston Group
Silurian/Devonian
18
England, Scotland
Rhosson Group
Ediacaran
25
Wales
Redbourne Group *
Jurassic
09
England, Irish Sea, English Channel
Rhynie Group
Devonian
17
Scotland
Riccarton Group
Silurian
19
Scotland
Roch Rhyolitic Group *
Ordovician
21
Wales
Rotliegendes Group
Permian
13
England, North Sea
Sarclet Group
Devonian
17
Scotland
Scottish Coal Measures Group
Carboniferous
15
Scotland
Selborne Group
Cretaceous
07
England, English Channel
Sherwood Sandstone Group
Permian/Triassic
12
England, Scotland
Shetland Group
Cretaceous/Palaeogene
06
Atlantic Ocean, North Sea
Skerry Group
Jurassic
09
Atlantic Ocean
Skiddaw Group
Ordovician
21
England
Skiddaw Slates Group *
Ordovician
21
England
Skrinkle Sandstones Group
Devonian
17
Wales
Skye Lava Group
Palaeogene
05
Scotland
Sleat Group
Stenian
31
Scotland
Snowdon Volcanic Group
Ordovician
21
Wales
Solent Group
Palaeogene
05
England
Solva Group
Cambrian
23
Wales
South Wales Coal Measures Group
Carboniferous
15
Wales
Southern Highland Group
Ediacaran/Cambrian
24
Scotland
Stewartry Group
Permian
13
Scotland
Stirling Group *
Silurian
19
Scotland
Stockdale Group
Silurian
19
England
Stockingford Shale Group
Cambrian
23
England
Stoer Group
Ectasian/Stenian
32
Scotland
Stonehaven Group
Silurian
19
Scotland
Strathclyde Group
Carboniferous
15
Scotland
Stratheden Group
Devonian
17
Scotland
Strathmore Group
Devonian
17
Scotland
Stretton Group
Ediacaran
25
England
Stronsay Group
Palaeogene
05
Scotland, Atlantic Ocean, North Sea
Sutherland Group
Jurassic
09
Scotland
Tamar Group
Devonian
17
England
Tappins Group
Ordovician
21
Scotland
Tarskavaig Group
Stenian
31
Scotland
Teign Valley Group
Carboniferous
15
England
Thames Group
Palaeogene
05
England, English Channel
Torridon Group
Stenian/Tonian
30
Scotland
Tranearth Group
Silurian
19
England
Trawden Limestone Group
Carboniferous
15
England
Treffynnon Group
Ediacaran/Cambrian
24
Wales
Treginnis Group
Cryogenian/Ediacaran
26
Wales
Treglemais Group
Cryogenian/Ediacaran
26
Wales
Unst Phyllite Group
Ordovician/Silurian
20
Scotland
Upper Old Red Group
Carboniferous
15
North Sea
Upper Old Red Sandstone Group
Devonian/Carboniferous
16
England, Scotland, Wales, North Sea
Uriconian Group
Ediacaran
25
England
Warwickshire Group
Carboniferous/Permian
14
England, Scotland, Wales
Waterhead Group
Silurian
19
Scotland
Wealden Group
Cretaceous
07
England, English Channel
Wentnor Group
Ediacaran
25
England
West Sole Group
Jurassic
09
North Sea
Westray Group
Palaeogene/Neogene
04
Scotland, North Sea
Whitehurst Group
Carboniferous
15
Yesnaby Sandstone Group
Devonian
17
Scotland
Yoredale Group
Carboniferous
15
England, Scotland
Zechstein Group
Permian
13
England, Atlantic, North Sea
Supergroups
The following 'supergroups', i.e. assemblages of 'groups', are recognised:
Subgroups
The following 'subgroups', i.e. subdivisions of 'groups', have been named:[ 3] [ 4]
Albion Glacigenic Group :
Shetland Glacigenic (Albion) Subgroup
Western Isles (Albion) Glacigenic Subgroup
Northwest Highlands (Albion) Glacigenic Subgroup
Banffshire Coast and Caithness (Albion) Glacigenic Subgroup
Inverness (Albion) Glacigenic Subgroup
East Grampian (Albion) Glacigenic Subgroup
Logie-Buchan (Albion) Glacigenic Subgroup
Central Grampian (Albion) Glacigenic Subgroup
Mearns (Albion) Glacigenic Subgroup
Midland Valley (Albion) Glacigenic Subgroup
Borders (Albion) Glacigenic Subgroup
Southern Uplands (Albion) Glacigenic Subgroup
Irish Sea Coast (Albion) Glacigenic Subgroup
Manx (Albion) Glacigenic Subgroup
Central Cumbria (Albion) Glacigenic Subgroup
North Pennine (Albion) Glacigenic Subgroup
North Sea Coast (Albion) Glacigenic Subgroup
Wales (Albion) Glacigenic Subgroup
Appin Group :
Ardmillan Group :
Argyll Group :
Badenoch Group :
Britannia Catchments Group :
Northern Highlands and Argyll Catchments Subgroup
Grampian Catchments Subgroup
Tay Catchments Subgroup
Forth Catchments Subgroup
Clyde Catchments Subgroup
Tweed Catchments Subgroup
Solway Catchments Subgroup
Northumbria Catchments Subgroup
Isle of Man Catchments Subgroup
Cheshire-North Wales Catchments Subgroup
Yorkshire Catchments Subgroup
Trent Catchments Subgroup
Severn and Avon Catchments Subgroup
West Wales Catchments Subgroup
Ouse-Nene Catchments Subgroup
Yare Catchments Subgroup
Somerset Catchments Subgroup
Thames Catchments Subgroup
Suffolk Catchments Subgroup
Cornubian Catchments Subgroup
Solent Catchments Subgroup
Sussex Catchments Subgroup
South Kent Catchments Subgroup
Grampian Group
Caledonia Glacigenic Group :
Shetland Glacigenic Subgroup
Western Isles Glacigenic Subgroup
Northwest Highlands Glacigenic Subgroup
Banffshire Coast and Caithness Glacigenic Subgroup
Inverness Glacigenic Subgroup
East Grampian Glacigenic Subgroup
Logie-Buchan Glacigenic Subgroup
Central Grampian Glacigenic Subgroup
Mearns Glacigenic Subgroup
Midland Valley Glacigenic Subgroup
Borders Glacigenic Subgroup
Southern Uplands Glacigenic Subgroup
Irish Sea Coast Glacigenic Subgroup
Manx Glacigenic Subgroup
Central Cumbria Glacigenic Subgroup
North Pennine Glacigenic Subgroup
North Sea Coast Glacigenic Subgroup
Wales Glacigenic Subgroup
Lower Old Red Sandstone Group :
Pembroke Limestone Group :
Ogwen Group
References
^ Definitions and procedures , section 4i
^ Trewin, N.H. (ed) 2002 The Geology of Scotland , The Geological Society, London p72/3
^ Appin, Argyll & Grampian subgroups after Trewin, N.H. (ed) 2002 The Geology of Scotland , The Geological Society, London p97
^ Britannia catchments, Albion Glacigenic and Caledonia Glacigenic listings from: MCMILLAN, A A, HAMBLIN, R J O, and MERRITT, J W. 2005. An overview of the lithostratigraphical framework for the Quaternary and Neogene deposits of Great Britain (Onshore) . British Geological Survey Research Report RR/04/04 38pp. ISBN 0 85272 516 7