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.

More information Group, Period ...

[1]

[2]

List of geological groups of Great Britain

Supergroups

Subgroups

References

Wikiwand - on

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