The BGS Lexicon of Named Rock Units — Result Details

Thurstaston Sandstone Member

Computer Code: THUN Preferred Map Code: TsS
Status Code: Full
Age range: Early Triassic Epoch (TE) — Anisian Age (TA)
Lithological Description: Sandstone, reddish-orange and rare pebbly sandstone, reddish-grey. Predominantly fine-grained; well-sorted with spherical to sub spherical grains. Rare laterally impersistent pebbly sandstone beds up to 3m thick in lower part. Soft sediment deformation common in pebble-free units. Less well-cemented in comparison to overlying Delamere Sandstone Member.
Definition of Lower Boundary: Taken at base of a maximum 3m thick pebbly sandstone bed (the 'Thurstaston Hard Sandstone Bed'), overlying pebble-free reddish-orange sandstone of the Wilmslow Sandstone Formation.
Definition of Upper Boundary: At boundary of weakly-cemented, pebble-free sandstone and overlying pebbly sandstone of the Delamere Sandstone Member (Helsby Sandstone Formation).
Thickness: 58m in Hoylake Water Works No.2 Borehole (SJ28NW/5). Wirral. 62m in Hoylake Water Works No.1 Borehole (SJ28NW/4). Wirral.
Geographical Limits: Cheshire Basin; possibly southern part of the East Irish Sea Basin.
Parent Unit: Helsby Sandstone Formation (HEY)
Previous Name(s): Upper Mottled Sandstone [Obsolete Name And Code: See WLSF And WRS] (UMS)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  A450, Thurstaston road cutting. 300-600m north of junction with Station Road and Thurstaston Road. Thompson, D B, 1970a. 
Reference Section  Hoylake Water Works No.2 Borehole (SJ28NW/5). 9.15-67.07m from surface. Hough, E, 1999. 
Reference Section  Hoylake Water Works No.1 Borehole (SJ28NW/4). 3.04-65.54m from surface. Hough, E, 1999. 
Reference(s):
Thompson, D B, 1970. The stratigraphy of the so-called Keuper Sandstone Formation (Scythian-?Anisian) in the Permo-Triassic Cheshire Basin. Quarterly Journal of the Geological Society of London, Vol.126, p.151-181. 
Wedd, C B, Smith, B, Simmons, W C and Wray, D A, 1923. The Geology of Liverpool, with Wirral and part of the Flinthsire Coalfield. Memoir of the Geological Survey of Great Britain, Sheet 96 (England and Wales). 
Rice, R C, 1939. The Trias of north-west Wirral. Proceedings of the Liverpool Geological Society 17, 349-370. 
Earp, J R and Taylor, B J, 1986. Geology of the country around Chester and Winsford. Memoir of the British Geological Survey, Sheet 109 (England and Wales). 
Ambrose, K, Hough, E, Smith, N J P and Warrington, G. 2014. Lithostratigraphy of the Sherwood Sandstone Group of England, Wales and south-west Scotland. British Geological Survey Research Report, RR/14/01. 
Thompson, D B, 1970B. Sedimentation of the Triassic (Scythian) Red Pebbly Sandstones in the Cheshire Basin and its margins. Geological Journal 7, Pt.1, 183-216. 
Hough, E, 1999. The geology of the north Wirral district. British Geological Survey Technical Report WA/98/66. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E096