The BGS Lexicon of Named Rock Units — Result Details

St Bees Sandstone Member

Computer Code: SBS Preferred Map Code: SBS
Status Code: Full
Age range: Early Triassic Epoch (TE) — Early Triassic Epoch (TE)
Lithological Description: Red-brown, very fine- to medium-grained, commonly micaceous sandstones, generally cross bedded, some parallel lamination; mudstone clasts locally common, subordinate thin beds of greenish grey sandstone.
Definition of Lower Boundary: Taken at the base of the lowest main/significant sandstone in the beds transitional with the underlying St Bees Shale Formation. The base is sharply marked on the gamma-ray log; an abrupt change from a highly serrated signature in the lowermost St Bees Sandstone to a much more subdued signature with higher values in the St Bees Shales.
Definition of Upper Boundary: Taken at the sharp upward change from generally fine-grained, well cemented sandstones, with features typical of fluvial deposition, to coarser, more friable sandstones with common well rounded aeolian grains (Calder Sandstone Formation). Marked also by an abrupt decrease in gamma ray values and increase in sonic interval transit time.
Thickness: 340 - 627m proved in UK NIREX Sellafield boreholes.
Geographical Limits: South and west Cumbria, Solway Basin, Vale of Eden. Also includes the 'Lower' St Bees Sandstone of the East Irish Sea Basin.
Parent Unit: Chester Formation (CHES)
Previous Name(s): St Bees Sandstone (-1162)
"Lower" St Bees Sandstone (-4316)
St Bees Sandstone Formation [Obsolete entry, use SBS] (-5239)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Cliffs (coastal) and quarry sections at St Bees Head, Cumbria, between Salton Bay and St Bees. 
Reference Section  Coastal (cliff) exposures, Maryport, Cumbria. 
Reference Section  Hawcoat Quarry, Barrow in Furness. 
Reference(s):
Jackson, D I, Mulholland, P, Jones, S M and Warrington, G, 1987. The geological framework of the East Irish Sea Basin. 191-203 in Brooks J and Glennie, K (editors), Petroleum Geology of North West Europe. [Graham and Trotman.] 
Barnes, R P, Ambrose, K, Holliday, D W, and Jones N S. 1994. Lithostratigraphical subdivision of the Triassic Sherwood Sandstone Group in west Cumbria. Proceedings of the Yorkshire Geological Society, Vol. 50, 51-60. 
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:
E024 E058 E018 E022 E037 E011 E017 E023 S006 S011 E040 E028 E012 E031