The BGS Lexicon of Named Rock Units — Result Details
Chale Clay Member
| Computer Code: | CECL | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Aptian Age (KP) — Aptian Age (KP) | ||
| Lithological Description: | Pale bluish grey mudstone, chocolate brown at the base. Bed 3 is a chocolate brown mudstone, gritty at base overlain by pale blue sandy mudstone with fragments of pyritised wood, bivalves and clay-ironstone nodules. Bed 5, of brown mudstone with a cementstone at its base, is overlain by the major part of the member that comprises pale bluish, grey poorly-laminated mudstone with irregular small nodules and red clay-ironstone nodules. | ||
| Definition of Lower Boundary: | Conformable at the boundary between hard, greenish, calcareous, coarse-grained sandstone (Simpson, 1985 Bed 2; the Perna Member) and the slightly gritty base of chocolate-brown mudstone (Simpson, 1985 Bed 3 of this member) | ||
| Definition of Upper Boundary: | The boundary is placed (Simpson, 1985) at the base of his Bed 7, which is identified by the upward change from pale grey, poorly-laminated mudstone (of Bed 6) into pale blue grey mudstone with small brown nodules (Lower Lobster Member). | ||
| Thickness: | 18 to 19m. | ||
| Geographical Limits: | Isle of Wight at the type-site. Not easily distinguished elsewhere in the outcrop or absent. | ||
| Parent Unit: | Atherfield Clay Formation (AC) | ||
| Previous Name(s): | Atherfield Clay [Obsolete Name and Code: Use AC, CECL]
(-2555)
Atherfield Clay sensu Fitton (1847, p. 296 part of Bed 3) [Obsolete Name and Code: Use CECL] (-2678) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Reference Section | The coastal cliff section at Compton Bay [SZ 372 848], Isle of Wight. Where the full succession is seen. | ||
| 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]. Specifically the steep cliff at Atherfield Point [SZ 4535 7905]. | ||
| Reference Section | The coastal cliff section at Red Cliff, Sandown [SZ 626 855]. Where the full but thin succession is seen but where the section is often obscured by landslides. | ||
| Reference(s): | |||
| 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 | |||