| Computer Code: |
CGMG |
Preferred Map Code: |
CM |
| Status Code: |
Full |
| Age range: |
Neoproterozoic Era (AZ)
— Neoproterozoic Era (AZ) |
| Lithological Description: |
Flaggy to blocky feldspathic and micaceous psammites. Minor semipelite interbeds and calc-silicate rock lenses. Rare feldspathic quartzite. |
| Definition of Lower Boundary: |
Sharply transitional - marked by incoming of flaggy psammites above semipelite-psammite interbeds of the Ardair Semipelite Formation. |
| Definition of Upper Boundary: |
Sharply transitional into overlying fissile, schistose semipelites of the Clachaig Formation. |
| Thickness: |
500m - 765m maximum. |
| Geographical Limits: |
Southern Monadhliath Mountains: Glen Roy - Laggan - Glen Banchor districts. |
| Parent Unit: |
Corrieyairack Subgroup (GRCO)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
East side of Beinn a' Chaorainn in Coire na H-uamha, North Glen Spean. |
| Reference Section |
Roadcuts on A86 and small quarry north of Lower Loch Laggan. |
| Reference Section |
Markie Burn, 700m upstream from Spey Dam. |
| Reference(s): |
| British Geological Survey. 1995. Glen Roy, Scotland sheet 63W. Solid Geology 1:50 000 (Keyworth, Nottingham: British Geological Survey.) |
| Key, R M, Clark, G C, May, F, Phillips, E R, Chacksfield, B C and Peacock, J D, 1997. Geology of the Glen Roy district. Memoir of the British Geological Survey, Sheet 63W [Scotland]. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
S074
S063
S063
|
