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.

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.

Supergroups
The following 'supergroups', i.e. assemblages of 'groups', are recognised:
 * Carboniferous Limestone Supergroup
 * Culm Supergroup
 * Dalradian Supergroup
 * Great Britain Superficial Deposits Supergroup
 * Leadhills Supergroup
 * Loch Ness Supergroup
 * Longmyndian Supergroup
 * Moine Supergroup - deprecated
 * New Red Sandstone Supergroup
 * Old Red Sandstone Supergroup
 * Pebidian Supergroup
 * Wester Ross Supergroup
 * Windermere Supergroup

Subgroups
The following 'subgroups', i.e. subdivisions of 'groups', have been named:

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:
 * Blair Atholl Subgroup
 * Ballachulish Subgroup
 * Lochaber Subgroup

Ardmillan Group:
 * Ardwell Subgroup
 * Drummuck Subgroup
 * Whitehouse Subgroup

Argyll Group:
 * Tayvallich Subgroup
 * Crinan Subgroup
 * Easdale Subgroup
 * Islay Subgroup

Badenoch Group:
 * Dava Subgroup
 * Glen Banchor Subgroup

Britannia Catchments Group: Grampian 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
 * Glen Spean Subgroup
 * Corrieyairack Subgroup
 * Glenshirra Subgroup

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:
 * Brecon Subgroup
 * Cosheston Subgroup
 * Ditton Subgroup
 * Downton Subgroup
 * Milford Haven Subgroup

Pembroke Limestone Group:
 * Blackrock Limestone Subgroup
 * Clydach Valley Subgroup

Ogwen Group
 * Nant Ffrancon Subgroup