The BGS Lexicon of Named Rock Units — Result Details
Kentisbury Slates Member
| Computer Code: | KSL | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Full, without ratification | ||
| Age range: | Givetian Age (DV) — Frasnian Age (DR) | ||
| Lithological Description: | Alternating groups of slate-rich and sandstone-rich units. Slate units are composed of dark grey and silvery grey slates, commonly with lenticles of silt or fine sand and beds of sandstone (up to 0.5 m thick) and limestone (up to 0.2 m thick). Sandstone-rich units are composed of massive grey or pinkish-grey coarse-grained sandstone up to 2 m thick, slates and some thinner, finer-grained, cross-bedded sandstones up to 1 m thick. | ||
| Definition of Lower Boundary: | Located 30 m above the top of the David's Stone Limestone (two beds of limestone separated by slates identified at [SS 5703 4742]); the boundary is distinguished by a change from limestones (below) to thickly-bedded sandstone (above). | ||
| Definition of Upper Boundary: | Junction with the overlying Morte Slates is seen clearly on the coast. The top beds of the Kentisbury Slates are comprised of silvery grey, smooth calcareous slates with current-bedded sandstones (at [SS 5021 4714]); the lowest beds of the overlying Morte Slates at [SS 4972 4720] are described as bluish grey or silvery grey slates which are commonly silty. The junction between the Kentisbury Slates and the overlying Morte Slates forms a clear topographical feature inland. | ||
| Thickness: | Up to 150 m. | ||
| Geographical Limits: | North Devon; broad outcrop trending NW-SE from Ilfracombe on the coast to Simonsbath; the high ground of Mattocks Down, Kentisbury Down, Rowley Down, Challacombe Common, Chains Barrow, Dure Down and Prayway Head. | ||
| Parent Unit: | Ilfracombe Slates Formation (IFS) | ||
| Previous Name(s): | Ilfracombe Beds
(ILFB)
David's Hole Beds (DVHB) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Area | Kentisbury Down, North Devon. | ||
| Reference(s): | |||
| Holwill F J W, House M R, Lane R, Gauss G A, Hendriks E M L and Dearman W R. 1969. Summer (1966) field meeting in Devon and Cornwall. Proceedings of the Geologists Association, Vol. 80, pp 43-62. | |||
| Evans, J W. 1922. The geological structure of the country round Combe Martin. Proceedings of the Geologists' Association, Vol.33, 201-228. | |||
| Evans J W and Stubblefield C J, 1929. Handbook of the geology of Great Britain. (London: Thomas Murby & Co.) | |||
| Edmonds, E A, Williams, B J and Taylor, R T. 1979. Geology of Bideford and Lundy Island. Memoir of the Geological Survey of Great Britain, Sheets 292 with 275, 276, 291, and part of 308 (England and Wales). | |||
| Holwill F J W. 1964. The coral fauna from the Ilfracombe Beds of north Devon. Proceedings of Ussher Society, Vol. 1, 00. 126-129. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E277 | |||