The BGS Lexicon of Named Rock Units — Result Details

Upper Lobster Member

Computer Code: ULOB Preferred Map Code: notEntered
Status Code: Full
Age range: Aptian Age (KP) — Aptian Age (KP)
Lithological Description: Alternations of dark grey sandy mudstone (Beds 15, 17 and 19) and mid to dark grey firm sandstone (Beds 16 and 18) with flat nodules in the lower two beds.
Definition of Lower Boundary: Boundary placed at the conformable upward change from hard brown sandstone (Bed 14) of The Crackers Member into sporadically glauconitic brown sandy mudstone (Bed 15) of the Upper Lobster Member.
Definition of Upper Boundary: The boundary is placed at the rapid conformable change from dark grey sandy mudstone of Bed 19 (Simpson, 1985) up into the muddy glauconitic sandstones of the Ferruginous Sands Formation.
Thickness: 14.5m at the type site.
Geographical Limits: Isle of Wight and in Dorset with equivalent beds around the Weald.
Parent Unit: Atherfield Clay Formation (AC)
Previous Name(s): Crackers Group (-2478)
Alternative Name(s): none recorded or not applicable
Reference Section  The coastal cliff section at Compton Bay [SZ 372 848], Isle of Wight. Generally a full succession visible. 
Type Section  Defined as the coastal cliff section of Chale Bay Isle of Wight between Shepherd's Chine [SZ 4466 7982] and Whale Chine [SZ 4684 7825]. Seen at beach level 0.9km [SZ 4610 7880] west of Whale Chine. 
Reference Section  The coastal cliff section at Red Cliff, Sandown [SZ 626 855]. A full succession but generally obscured by landslide debris. 
Osborne White, H J. 1921 [1994 reprint]. A short account of the geology of the Isle of Wight. Memoirs of the Geological Survey of Great Britain. 235pp. [HMSO.] 
Fitton, W H. 1847. A stratigraphical account of the section from Atherfield to Rocken-end on the south-west coast of the Isle of Wight. Quarterly Journal of the Geological Society of London, Vol.3, 289-327. 
Simpson, M I. 1985. The stratigraphy of the Atherfield Clay Formation (Lower Aptian, Lower Cretaceous) at the type and other localities in southern England. Proceedings of the Geologists' Association, Vol.96(1), 23-45. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable