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:
Reference Section  Hoylake Water Works No.1 Borehole (SJ28NW/4). 3.04-65.54m from surface. Hough, E, 1999. 
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(s):
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. 
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). 
Hough, E, 1999. The geology of the north Wirral district. British Geological Survey Technical Report WA/98/66. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E096