| Computer Code: |
ACHN |
Preferred Map Code: |
symb |
| Status Code: |
Full |
| Age range: |
Tonian Period (AT)
— Tonian Period (AT) |
| Lithological Description: |
Psammite and semipelite, interbanded. Semipelite is muscovite-rich and locally migmatitic. |
| Definition of Lower Boundary: |
Not exposed. |
| Definition of Upper Boundary: |
Likely conformable contact with the overlying Tarve Psammite Formation (Loch Eil Group), via a transitional boundary. |
| Thickness: |
Not known. Likely > 1000 m. |
| Geographical Limits: |
Northern Highlands, along NW shore of Loch Ness from Invermoriston to Muir of Ord. Restricted to the Sgurr Beag Nappe. |
| Parent Unit: |
Glenfinnan Group (GLEN)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| none recorded or not applicable |
| Reference(s): |
| Strachan, R A, May, F and Barr, D, 1988. The Glenfinnan and Loch Eil Divisions of the Moine Assemblage. 32-45 IIV Winchester, J A (editor). Later Proterozoic stratigraphy of the Northern Atlantic regions (Glasgow and London: Blackie). |
| British Geological Survey. 1993. Invermoriston, Scotland. Sheet 73W. Solid Geology, 1:50 000 (Keyworth, Nottingham: British Geological Survey.) |
| 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: |
|
S073
S073
S083
|
