| Computer Code: |
TCA |
Preferred Map Code: |
TCA |
| Status Code: |
Full |
| Age range: |
Tonian Period (AT)
— Tonian Period (AT) |
| Lithological Description: |
Coarse to very-coarse, pebbly red sandstone, thick-bedded (0.5 - 5 m); locally medium grained. Thin subsidiary pebble conglomerates and grey siltstones. Planar and cross-bedding are common. Soft-sediment deformation is common but not ubiquitous. |
| Definition of Lower Boundary: |
Upon Diabaig Formation (TCD) or Kinloch Formation (Sleat Group - TB) via minor unconformity: elsewhere with angular unconformity upon Stoer Group (TA) or Lewisian Gneiss (L). |
| Definition of Upper Boundary: |
Conformably overlain by the Aultbea Formation (TCAU), with gradational boundary, with incoming of consistent fine-medium grained sandstone. |
| Thickness: |
c. 2500 m. |
| Geographical Limits: |
Northwest Highlands, from Cape Wrath to Rum. |
| Parent Unit: |
Torridon Group (TC)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| none recorded or not applicable |
| Reference(s): |
| Stewart, A D. 2002. The later Proterozoic Torridonian rocks of Scotland: their sedimentology, geochemistry and origin. Geological Society Memoir. Vol. 24. (The Geological Society.) |
| Rainbird, R.H., Hamilton, M.A. and Young, G.M., 2001. Detrital zircon geochronology and provenance of the Torridonian, NW Scotland. Journal of the Geological Society of London, 158: 15-27. |
| 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. |
| Stewart, A D and Donnellan, N C B, 1992. Geochemistry and provenance of red sandstones in the Upper Proterozoic Torridon Group in Scotland. Scottish Journal of Geology, Vol.28, 143-53. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
S107
S114
S071
S071
S107
S108
S081
S082
S092
S092
S101
S101
S081
S102
S113
S070
S091
|
