The BGS Lexicon of Named Rock Units — Result Details

Laimhrig Shale Member

Computer Code: TCDL Preferred Map Code: notEntered
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Laminated dark-grey "shales" (actually consisting of laminated mudstone, siltstone, and very fine- to fine-grained sandstone), with intercalated beds of pale grey fine-grained sandstone that increase in thickness and abundance towards the top of the member.
Definition of Lower Boundary: Highly variable gradational and/or interdigitating transition from the underlying Fiachanis Gritty Sandstone Member. (NM 3730 9366 or NM 3695 9905).
Definition of Upper Boundary: The 'first' (stratigraphically lowest) thickly-bedded, cross-stratified and/or convoluted fine- to medium-grained sandstone bed greater than 2 metres thick. (NM 4186 9604).
Thickness: 275m minimum in type-locality (stratigraphical base not visible).
Geographical Limits: Isle of Rhum, Laimhrig.
Parent Unit: Diabaig Formation (TCD)
Previous Name(s): Bagh Na H-Uamha Shale (-1221)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Isle of Rhum, Laimhrig. 
Reference(s):
Black, G P and Welsh, W, 1961. The Torridonian succession of the Isle of Rhum. Geological Magazine, Vol.98, 265-276. 
Nicholson, P, 1991. NERC/BGS mapping contract F60/62/38 Geological Mapping Sheet 60, Isle of Rhum. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S060