| 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 [Obsolete Name and Code: Use ULOB, TCRS]
(-2478)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
The coastal cliff section at Red Cliff, Sandown [SZ 626 855]. A full succession but generally obscured by landslide debris. |
| 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(s): |
| 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. |
| 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. |
| 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.] |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
