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
Stratotypes:
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. 
Reference(s):
Lexique Stratigraphique International. 1971. Volume 1, Europe, Fascicule 3a, England, Wales and Scotland, Part 3a VII, Lower Carboniferous (Dinantian). 
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. 
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