The BGS Lexicon of Named Rock Units — Result Details

Allt Mor Na H-Uamha Member

Computer Code: TCAM Preferred Map Code: CAM
Status Code: Full
Age range: Tonian Period (AT) — Tonian Period (AT)
Lithological Description: Cyclically interbedded "siltstones" and fine- to medium-grained cross-bedded sandstones (the "siltstones" actually consisting of siltstone and very fine- to fine-grained sandstone with subordinate mudstone); the fine- to medium-grained cross-bedded sandstone beds increase in abundance towards the top of the Member.
Definition of Lower Boundary: Upon the Diabaig Formation (TCD). Base [NM 4205 9722]: at the lowest thickly-bedded (>2 m), cross-bedded and/or convoluted fine- to medium-grained sandstone.
Definition of Upper Boundary: Overlain by the Scresort Sandstone member (TCAS). Top [NM 4108 9751]: the incoming of thickly-bedded, cross-stratified and/or convoluted coarse-grained sandstone (arkose) bed containing 'exotic' pebbles characteristic of the Applecross Formation.
Thickness: 415m. in type locality.
Geographical Limits: Inner Hebrides: Rum, Soay.
Parent Unit: Applecross Formation (TCA)
Previous Name(s): Bagh Na H-Uamha Shale [Obsolete Name and Code: Use TCDL, TCAM] (-1221)
Rudha Na Roinne Grit [Obsolete Name and Code: Use TCAS, TCAM] (-1222)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Type Area - Isle of Rum, Allt Mor Na H-Uamha [NM 420 972 to NM 411 975]. 
Reference(s):
Black, G P and Welsh, W, 1961. The Torridonian succession of the Isle of Rhum. Geological Magazine, Vol.98, 265-276. 
Emeleus, C H. 1997. Geology of Rum and the adjacent islands. Memoir (sheet) of the Geological Survey of Great Britain (Scotland) (60). (The Stationery Office for the British Geological Survey.) 171pp. 
Stewart, A D. 2002. The later Proterozoic Torridonian rocks of Scotland: their sedimentology, geochemistry and origin. Geological Society Memoir. Vol. 24. (The Geological Society.) 
Krabbendam, M. 2021. A stratigraphic framework for the early Neoproterozoic successions of the Northern Highlands of Scotland. UK Stratigraphic Framework Series. British Geological Survey Open Report, OR/21/072. 86pp. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S060