The BGS Lexicon of Named Rock Units — Result Details

Birdoswald Limestone Group [Obsolete: use TYLS]

Computer Code: BLG Preferred Map Code: notEntered
Status Code: Index Level
Age range: Asbian Substage (CR) — Asbian Substage (CR)
Lithological Description: [Obsolete: use TYLS] Dark blue fossiliferous limestones with passage into sandy limestones and calcareous sandstones and grits: dark blue shales and mudstones with a dozen coal horizons.
Definition of Lower Boundary: Drawn at the base of Birdoswald Group the Lanercost Limestone Member where limestone and arenaceous sediment rests conformably upon sandstone and limestone of the Craighill Sandstone Group.
Definition of Upper Boundary: Drawn at the conformable upward passage of the Birdoswald Group where it is conformably overlain by the base of the Naworth Limestone of the Lower Limestone Group. Boundary based on biostratigraphy.
Thickness: 426 metres approx.
Geographical Limits: Confined to the surrounding area of Brampton between the counties of Cumberland and Northumberland.
Parent Unit: none recorded or not applicable
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  The area between Milton Rigg, Woodhouse. 
Reference(s):
Trotter, F M, 1925. The lower part of the Carboniferous Limestone series (within the Thirwell Coal) in the Brampton and Gilsland districts. "In" Summary of the progress of the Geological Survey of Great Britain and the Museum of Practical Geology for the year 1925. British Geological Survey. 
Trotter, F M and Hollingworth, S E. 1932. The geology of the Brampton District. Memoir of the Geological Survey, Sheet 18. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E018