The BGS Lexicon of Named Rock Units — Result Details

Lower Stromness Flagstone Formation

Computer Code: LSF Preferred Map Code: LSF
Status Code: Pending Upgrade
Age range: Eifelian Age (DI) — Eifelian Age (DI)
Lithological Description: Laminated, carbonate-rich siltstones and shales with subordinate fine-grained, thinly bedded sandstones.
Definition of Lower Boundary: Drawn at unconformity where flagstones overlie Yesnaby Sandstone Group or pre-Devonian basement.
Definition of Upper Boundary: Drawn at confromable upward passage to the Sandwick Fish Bed, upward passage being from sandstone and shale into limestone.
Thickness: c.250m
Geographical Limits: Orkney Islands
Parent Unit: Caithness Flagstone Group (CNFL)
Previous Name(s): Caithness Flagstone Series (-4751)
Lower Caithness Flagstone Group (-1642)
Lower Stromness Flags (-2923)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Western Mainland, Orkney Islands. 
Reference(s):
Mykura W, 1976 British Regional Geology: Orkney and Shetland (HMSO, Edinburgh).] 
Fletcher, T P. 1996, A review of the lithostratigraphy of the Old Red Sandstone Supergroup in Scotland north of a line from Fort William to Aberdeen. BGS Technical Report WA/96/39R. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S117 S117 S119 S119 S120 S121 S122