The BGS Lexicon of Named Rock Units — Result Details

Otter Sandstone Formation
Computer Code: OS Preferred Map Code: OS
Status Code: Full
Age range: Anisian Age (TA) — Ladinian Age (TD)
Lithological Description: Fine- to medium-grained sandstone, weathering to sand near surface. Sandstones locally micaceous and cross-bedded. Thin units of hard intraformational conglomerate; lenticular beds of reddish brown clay or mudstone locally; calcretes at some horizons. Lenticular pebble bed units mapped in the Exeter district.
Definition of Lower Boundary: Rests sharply on ventifact bed at top of Budleigh Salterton Pebble Beds, in area between coast and Hill Head (Uffculme). Base difficult to identify in Taunton district owing to upward passage from conglomerate to sandstone (Edmonds and Williams, 1985).
Definition of Upper Boundary: In coastal exposures (SY 110 8663), transitional into overlying Mercia Mudstone.
Thickness: Coast and Exeter district: c.160m. Taunton district: 30 to 60m
Geographical Limits: Extends from south Devon coast between Budleigh Salterton and Sidmouth, northwards to near Minehead on the north Somerset coast.
Parent Unit: Sherwood Sandstone Group (SSG)
Previous Name(s): Otter Sandstone (-437)
Otter Sandstones (-3599)
Upper Sandstone (-3792)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Sea cliffs between Budleigh Salterton and Sidmouth. 
Reference(s):
Howard, A S, Warrington, G, Ambrose, K, and Rees, J G. 2008. A formational framework for the Mercia Mudstone Group (Triassic) of England and Wales. British Geological Survey Research Report, RR/08/04. 
Ussher, W A E, 1902. The Geology of the country around Exeter. Memoir of the Geological Survey of Great Britain, Sheet 325. (England and Wales). 
Edmonds, E A and Williams, B J, 1985. Geology of the country around Taunton and the Quantock Hills. Memoir of the British Geological Survey, Sheet 295. (England and Wales). 
Laming, D J C, 1968. New Red Sandstone stratigraphy in Devon and West Somerset. Proceedings of the Ussher Society, Vol.2, p.23-25. 
Henson, M R, 1970. The Triassic rocks of south Devon. Proceedings of the Ussher Society, Vol.2, p.172-177. 
Selwood, E B, Edwards, R A, Simpson, S, Chesher, J A, Hamblin, R J O, Hanson, M R, Riddolls, B W and Waters, R A. 1984. Geology of the countryside around Newton Abbot. Memoir of the British Geological Survey, Sheet 339. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E339 E310 E311 E326 E340
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