The BGS Lexicon of Named Rock Units — Result Details

Yare Catchments Subgroup

Computer Code: YCAT Preferred Map Code: notEntered
Status Code: Full
Age range: Mid Pleistocene Epoch (QPM) — Holocene Epoch (QH)
Lithological Description: The Yare Catchments Subgroup encompasses all the fluvial, lacustrine and organic deposits of the rivers which occupy the catchment area of the River Yare and its tributaries, and also the other minor rivers that flow into the North Sea along the coast of Norfolk. Floodplain alluvium comprises soft silts and clays, commonly with beds of peat and a basal bed of sand and gravel. River terrace deposits are largely sand and gravel. The gravels are dominantly composed of subrounded to angular flint, including large cobbles, also rounded pebbles of quartz and quartzite, northern British erratics of glacial derivation, and a little chalk. Peat is a minor component, and minor marine deposits are included where they are intercalated in dominantly fluvial formations.
Definition of Lower Boundary: Formations of the Yare Valley Subgroup rest unconformably on glacial and periglacial deposits and upon Crag Group, London Clay Formation and Chalk Group bedrock.
Definition of Upper Boundary: Surface, or overlain by deposits of the Breydon Formation.
Thickness: c.18m
Geographical Limits: The entire catchment of the River Yare and its tributaries, and the whole of Norfolk to the north of that catchment.
Parent Unit: Britannia Catchments Group (BCAT)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  The valleys of the River Yare and its tributaries, in Norfolk. 
Reference(s):
McMillan, A A, Hamblin, R J O and Merritt, J W. 2005. An overview of the lithostratigraphical framework for the Quarternary and Neogene deposits of Great Britain (onshore). British Geological Survey Research Report RR/04/04. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E130 E131 E132 E146 E147 E148 E160 E161 E162 E175 E176 E190 E191