The BGS Lexicon of Named Rock Units — Result Details

Gleaston Formation [Obsolete Name And Code: Use AG]

Computer Code: GTGP Preferred Map Code: GlF
Status Code: Index Level
Age range: Brigantian Substage (CX) — Brigantian Substage (CX)
Lithological Description: Variable sequence of thinly interbedded dark grey to black limestone, shaly mudstone and subordinate sandstone. Limestones richly fossiliferous in places with coral-brachiopod fauna. A bed containing abundent algal nodules 'Girvanella Nodular Bed' commonly occurs just above the base.
Definition of Lower Boundary: Point where thickly bedded pale limestone of Urswick Limestone Formation passes up into the predominantly dark grey Gleaston Formation.
Definition of Upper Boundary: Taken at base of the Cravenoceras leion Marine Band.
Thickness: Variable 80-180m+
Geographical Limits: South Cumbria and North Lancashire, from Duddon estuary to Carnforth area.
Parent Unit: Yoredale Group (YORE)
Previous Name(s): Gleaston Group (-1576)
Yoredales (-1577)
Alternative Name(s): Alston Formation
Reference Section  Gleaston Castle Farm Borehole (SD27SE/51) depths 124.27m to bottom at 165.36m. Borehole at c.44m OD, c.700m north-west of Gleaston Castle. Proved top and upper 41.09m of the formation. 
Reference Section  Harbarrow No.1. Borehole SD27SE/37. Borehole, at c.52m OD, c.1000m north-west of Gleaston Castle, proved probably the whole formation, c.97m thick but not logged in detail. 
Dunham, K C and Rose, W C C. 1941. Geology of the iron-ore field of south Cumberland and Furness. Geological Survey of Great Britain, Wartime Pamphlet, No.16. 
Lexique Stratigraphique International. 1971. Volume 1, Europe, Fascicule 3a, England, Wales and Scotland, Part 3a VII, Lower Carboniferous (Dinantian). 
Rose, W C C. 1977. Geology and Hematite deposits of South Cumbria. Economic Memoir for 1:50,000 Sheet 58 and southern part of Sheet 48. Memoir of the geological Survey of Great Britain. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E059 E058 E048