The BGS Lexicon of Named Rock Units — Result Details

Tillybrachty Sandstone Formation

Computer Code: TIS Preferred Map Code: TIS
Status Code: Pending Upgrade
Age range: Lochkovian Age (DO) — Pragian Age (DP)
Lithological Description: Red, friable sandstone with conglomerate bands and thin intercalated lava flows.
Definition of Lower Boundary: Change from siltstone to sandstone.
Definition of Upper Boundary: Transitional, marked by incoming of rhythmically graded siltstone/sandstone units, disappearance of conglomerate bands, and lightening of colour.
Thickness: 250 metres at type section (possibly incomplete due to faulting); increases southwards to approx. 1400 metres around Kildrummy Castle (NJ 455 164); decreases northwards to approx. 100 metres near Boghead (NJ 521 278).
Geographical Limits: Not defined.
Parent Unit: Rhynie Group (RHN)
Previous Name(s): Tillybrachty Sandstones (-1233)
Alternative Name(s): none recorded or not applicable
Type Area  Craigs of Tillybrachty, 1:50,000 Sheet 76W, Scotland. 
Wilson, J S G. 1890. Explanation of Sheet 76 Central Aberdeenshire. Memoir of the Geological Survey (Scotland). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S076 S086