The BGS Lexicon of Named Rock Units — Result Details

Upper Stromness Flagstone Formation

Computer Code: USF Preferred Map Code: USF
Status Code: Pending Upgrade
Age range: Eifelian Age (DI) — Givetian Age (DV)
Lithological Description: Laminated carbonate-rich siltstones and shales with subordinate fine-grained thinly bedded sandstones.
Definition of Lower Boundary: Drawn at the base of the Sandwick Fish Bed, where limestone rests conformably upon laminated siltstones and minor sandstones of the Lower Stromness Flagstone Formation.
Definition of Upper Boundary: Drawn at the conformable upward passage from the flaggy siltstones of the Rousay Member to fluvial sandstone of the Lower Eday Sandstone Formation.
Thickness: c.560m
Geographical Limits: Orkney Islands
Parent Unit: Caithness Flagstone Group (CNFL)
Previous Name(s): CAITHNESS FLAGSTONE SERIES
UPPER STROMNESS FLAGS (USF)
Alternative Name(s): UPPER CAITHNESS FLAGSTONES
Stratotypes:
Type Area  Northern and western parts of the Mainland and island of Rousay, 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 Orcadian Old Red Sandstone Supergroup of northern Scotland. British Geological Survey 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