The BGS Lexicon of Named Rock Units — Result Details

Exmouth Mudstone and Sandstone Formation

Computer Code: EMSA Preferred Map Code: EMS
Status Code: Full
Age range: Early Triassic Epoch (TE) — Early Triassic Epoch (TE)
Lithological Description: Reddish brown silty mudstones with intercalated reddish brown lenticular sandstone beds, exceptionally to 30m thick, but mostly 5 to 10m thick. The thickest, most persistent, sandstones occur at the top, and probably correlate with sandstones exposed at Straight Point on the coast.
Definition of Lower Boundary: In Exeter district, lower boundary taken at sharp change from the sandstone of the underlying Dawlish Sandstone, to mudstone. Between Lympstone and Exmouth the formation rests sharply and probably unconformably on the Exe Breccia (Selwood and others, 1984).
Definition of Upper Boundary: See definition of lower boundary of Littleham Mudstone.
Thickness: About 200m in Exeter district; 255m on the coast (Selwood and others, 1984).
Geographical Limits: Extends from south Devon coast between Exmouth and Straight Point (SY 036 798) northwards through Exeter district to near Aylesbeare. Not recognised north of Aylesbeare (SY 030 923).
Parent Unit: Aylesbeare Mudstone Group (AYB)
Previous Name(s): Exmouth Sandstone And Mudstone Formation [Obsolete Name And Code: Use EMSA] (ESM)
Exmouth Mudstone And Sandstone Member (-4025)
Exmouth Sandstone And Mudstone (-4026)
Exmouth Sandstones And Mudstones (-4638)
Exmouth Formation (-889)
Exmouth Sandstones (-2785)
Alternative Name(s): none recorded or not applicable
Type Section  Sea cliffs between Exmouth and Straight Point. Exmouth (The Shrubbery) to Straight Point. Poorly exposed between The Shrubbery (SY 003 805) and Orcombe Point (SY 037 795); well exposed between Orcombe Point and Straight Point. 
Laming, D J C, 1982. The New Red Sandstone. "In" Durrance, E M and Laming, D J C, (Editors). The Geology of Devon, p.148-177. 
Henson, M R, 1972. The form of the Permo-Triassic Basin in south-east Devon. Proceedings of the Ussher Society, Vol.3, p.447-457. 
Selwood, E B, Edwards, R A, Simpson, S, Chesher, J A, Hamblin, R J O, Henson, 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 (England and Wales). 
Henson, M R, 1970. The Triassic rocks of south Devon. Proceedings of the Ussher Society, Vol.2, p.172-177. 
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, 1971. The Permo-Triassic rocks of south Devon. Unpublished PhD Thesis, University of Exeter. 
Edwards, R A, 1984. Geological notes and local details for 1:10 000 Sheet SY08NW, (Woodbury, Devon). British Geological Survey. 
1:50K maps on which the lithostratigraphical unit is found, and map code used: