Computer Code: |
FRM |
Preferred Map Code: |
FsS |
Status Code: |
Full |
Age range: |
Early Triassic Epoch (TE)
— Anisian Age (TA) |
Lithological Description: |
Sandstone, reddish-orange, predominantly fine-grained; well-sorted with spherical to subspherical-grains; large-scale dune bedding common; characrterised by presence of 'dome-shaped dune' structures. Weakly cemented in comparison to underlying Delamere Pebbly Sandstone Member. |
Definition of Lower Boundary: |
Lowermost occurrence of non-pebbly weakly-cemented sandstone, with characteristic 'dome-shaped dune' structures on the dominantly pebbly sandstone of the underlying Delamere Pebbly Sandstone Member. |
Definition of Upper Boundary: |
Uppermost occurrence of weakly-cemented non-pebbly sandstone with characteristic dome-shaped dune structures, under interbedded siltstone and subordinate sandstone of the Tarporley Siltstone Formation (Mercia Mudstone Group). |
Thickness: |
55m in the Marston region, North Cheshire. 30.14m at Ford Pumping Station (SJ28NE/3), Wirral. 21.1m in the Heron Road Borehole (SJ28NW/22), Wirral. |
Geographical Limits: |
Cheshire Basin; possibly also the southern part of the East Irish Sea Basin. |
Parent Unit: |
Helsby Sandstone Formation (HEY)
|
Previous Name(s): |
Basement Beds [Obsolete Name and Code: Use WAR, HEY, BRCT, BABE, LFSB, LLW, DELA, FRM, PLT, FRFA, PFLD, DDC]
(-3812)
|
Alternative Name(s): |
none recorded or not applicable
|
Stratotypes: |
Type Section |
Railway cutting, north-east from Frodsham Railway Station, Cheshire (Thompson, 1969, 1970a). |
Type Area |
Ford Pumping Station (SJ28NE/3), 157.31 - 187.45 m below surface (Hough, 1999). |
Reference Section |
Heron Road Borehole, Saughall Massie, Wirral. 117.4-138.5 m from surface (Hough, 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. |
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. |
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. |
Thompson, D B, 1969. Dome-shaped Aeolian dunes in the Frodsham Member of the so-called 'Keuper' Sandstone Formation, (Scythian ?Anisian-Triassic) at Frodsham, Cheshire, England. Sedimentary Geology 3, 263-289. |
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
|