The BGS Lexicon of Named Rock Units — Result Details

Sgor Mhor Sandstone Member

Computer Code: TCSM Preferred Map Code: notEntered
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Fine- to medium-grained sandstones containing no "exotic" pebbles, and displaying an abundance of horizontal-stratification (in addition to cross-stratification and soft-sediment convolution structures); detrital heavy minerals of silt to fine-grained sand grade occur commonly as dark laminae or as prominent dark beds up to 2m thick.
Definition of Lower Boundary: Base: (eg NM 3769 9147 or NG 3360 0247) : marked by the disappearance of 'exotic' pebbles characteristic of the Applecross Formation.
Definition of Upper Boundary: Top: not seen (nor defined) on Rhum.
Thickness: Minimum thickness (from NM 3698 9106 to NM 3659 9172) of 175m. (Stratigraphical top is nowhere visible; in the type locality the stratigraphical base and top are not visible).
Geographical Limits: Isle of Rhum, Sgor Mhor.
Parent Unit: Aultbea Formation (TCAU)
Previous Name(s): Guirdil Arkose (-3074)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Isle of Rhum, Sgor Mhor. 
Reference(s):
Black, G P and Welsh, W, 1961. The Torridonian succession of the Isle of Rhum. Geological Magazine, Vol.98, 265-276. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S060