The BGS Lexicon of Named Rock Units — Result Details

Itchen Formation

Computer Code: ITCH Preferred Map Code: notEntered
Status Code: Full
Age range: Early Pleistocene Epoch (QPE) — Holocene Epoch (QH)
Lithological Description: Floodplain alluvium and river terrace deposits. The floodplain alluvium comprises overbank deposits of brown organic silty clay, together with peaty clay and peat, overlying sand and gravel. Tufa occurs as 1 to 2m-high raised hummocky spreads. The surviving river terrace deposits comprise sand and gravel, planar bedded or cross-bedded, locally overlain by overbank deposits of clayey and sandy silts and silty clays. These fine-grained deposits may be partly aeolian in origin. The major gravel lithology is flint, dominantly sub-rounded to sub-angular and a little well-rounded, and subordinate quartz, ironstone and "sarson". The sand fraction is composed of fine- to coarse-grained well-rounded quartz grains, with subangular flint in the coarse fraction. The older, higher terraces are commonly cryoturbated.
Definition of Lower Boundary: Unconformable on Palaeogene and Cretaceous bedrock.
Definition of Upper Boundary: Surface.
Thickness: To c.12m
Geographical Limits: The catchment of the River Itchen and its tributaries in the Southampton-Alresford area.
Parent Unit: Solent Catchments Subgroup (SNTCA)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  The valley of the River Itchen and its tributaries in the Southampton-Alresford area. Edwards and Freshney, 1987. 
Reference(s):
Edwards, R A and Freshney, E C. 1987. Geology of the country around Southampton. Memoir of the British Geological Survey, Sheet 315 (England and Wales). 
Booth, K A. 2002. Geology of the Winchester District - a brief explanation of the geological map. Sheet Explanation of the British Geological Survey. 1:50 000 Sheet 299, Winchester (England and Wales). 
Farrant, A R. 2002. Geology of the Alreford district - a brief explanation of the geological map. Sheet explanation of the British Geological Survey. 1:50 000 sheet 300 Alresford [England and Wales]. 30pp. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E299 E300 E315