| Computer Code: |
TCSM |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Tonian Period (AT)
— Tonian Period (AT) |
| Lithological Description: |
Fine- to medium-grained sandstones without "exotic" pebbles, thick-bedded. Abundant cross-bedding and convolute, soft-sediment deformation structures. Detrital heavy minerals of silt to fine-grained sand grade common. |
| 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: |
Inner Hebrides: Rum. |
| Parent Unit: |
Aultbea Formation (TCAU)
|
| Previous Name(s): |
Guirdil Arkose [Obsolete Name and Code: Use TCAS, TCSM]
(-3074)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Type Area - Isle of Rhum, Sgor Mhor: Guirdial Bay to Camas na h-Atha [NG 315 011 to NM 301 996]. |
| Reference(s): |
| 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. |
| 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
|
