The BGS Lexicon of Named Rock Units — Result Details

Stretton Shale Formation

Computer Code: SNSH Preferred Map Code: notEntered
Status Code: Pending Upgrade
Age range: Ediacaran Period (AD) — Ediacaran Period (AD)
Lithological Description: Greenish grey, laminated mudstones and siltstones.
Definition of Lower Boundary: Uncertain, formerly taken at the base of the Helmeth Grit Member (Greig et al, 1968), although more recent work (Pauley, 1990) suggests that the latter forms part of the apparently underlying Ragleth Tuff Formation. Alternatively, it may underlie or form part of the Ragleth Tuff. The boundary between the Helmeth Grit Member and the Stretton Shale Formation has been variously interpreted as conformable (Greig et al, 1968 and other authors) or unconformable (Pauley, 1990).
Definition of Upper Boundary: Generally taken at the relatively sharp, conformable contact with the base of the Buxton Rock Member, the lowest division of the Burway Formation. However the transition from the mudstone dominated Stretton Shale Formation into the sandstone dominated Burway Formation takes place over several metres.
Thickness: Over 900m thick.
Geographical Limits: Welsh Borderland, Shropshire, Church Stretton and Long Mynd.
Parent Unit: Stretton Group (YST)
Previous Name(s): Stretton Shale Group (-3687)
Stretton Shale (-3041)
Stretton Shale Formation [Obsolete Code: Use SNSH] (YSH)
Alternative Name(s): Watling Shales; Brockhurst Shales
Stratotypes:
Reference Section  From western flanks of Wart Hill to the vicinity of Cwm Head. Greig D C, et al., 1968. 
Reference(s):
Pauley J C. 1986. The Longmyndian Supergroup: facies, stratigraphy and structure. Unpublished phD Thesis, University of Liverpool. Liverpool. 
Greig D C, Wright, J E, Hains, B A and Mitchell, G H. 1968. Geology of the country around Church Stretton, Craven Arms, Wenlock Edge and Brown Clee. Memoir of the Geological Survey, Sheet 166 (England and Wales). (London: H.M.S.O.). 379pp. 
Pauley J C. 1990. The Longmyndian Supergroup and related Precambrian sediments of England and Wales. 5-27 in Avalonian and Cadomain geology of the North Atlantic. Strachan R A and Taylor G K (editors). (Glasgow: Blackie). 
Pauley J C. 1991. A revision of the stratigraphy of the Longmyndian Supergroup, Welsh Borderland, and of its relationship to the Uriconian volcanic complex. Geological Journal, Vol. 26, 167-183. 
Lapworth C and Watts W W. 1910. Shropshire. 739-769 in Geology in the field; the Jubilee Volume of the Geologists' Association (1858-1908). Monckton H W and Herries R S (editors). (London: Edward Stanford). 
Pauley J C. 1990. Sedimentology, structural evolution and tectonic setting of the Late Precambrian Longmyndian Supergroup of the Welsh Borderland, UK. 341-351 in the Cadomian Orogeny. D'Lemos R S, Strachan R A and Topley C G (editors). Geological Society of London Special Publication No. 51. 
Cobbold, E S. 1901. The geology of the Church Stretton district. 1-115 in Church Stretton vol 1. Campbell-Hyslop, C W (Editor). No. 1. (Shrewsbury: L Wilding). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E166