Computer Code: |
APP |
Preferred Map Code: |
App |
Status Code: |
Full |
Age range: |
Neoproterozoic Era (AZ)
— Neoproterozoic Era (AZ) |
Lithological Description: |
Alternating units of psammite to quartzite and semipelite to pelite in Lochaber Subgroup. In the Ballachulish and Blair Atholl Subgroups, pelitic and calcareous lithologies dominate, although one clean-washed, locally pebbly quartzite in the Ballachulish Subgroup is persistent from Donegal to Banffshire. Many of the pelitic and calcareous rocks are graphitic. |
Definition of Lower Boundary: |
Generally rapid transition from monotonous psammite, generally flaggy, with thin quartzite and semipelite units of underlying Grampian Group, to better sorted psammite or quartzite and semipelite or pelite. |
Definition of Upper Boundary: |
Transition from graphitic semipelite and limestone to psammite and quartzite with rare semipelite, or locally to diamictite. |
Thickness: |
Typically 4km where untectonised, but thinned sequence (1km or less) occurs over structural highs. |
Geographical Limits: |
Connemara; North Mayo; Donegal west of Main Donegal Granite; Lismore to Glen Spean; Kinlochlaggan; Kinloch Rannoch via Glen Shee to Braemar; Glen Livet; Dufftown to Banffshire coast (Findlater Castle to Portsoy). The Appin Group is also roughly equivalent to the Scatsta Division of Shetland. |
Parent Unit: |
Dalradian Supergroup (DALN)
|
Previous Name(s): |
Lower Dalradian Group [Obsolete Name And Code: See APP]
(DA)
|
Alternative Name(s): |
Lower Dalradian
|
Stratotypes: |
Type Area |
Appin, Lismore, Loch Leven. |
Reference(s): |
Harris, A L and Pitcher, W S, 1975. The Dalradian Supergroup. "In" Harris, A L, Shackleton, R M, Watson, J, Downie, C, Harland, W B and Moorbath, S. A correlation of the Precambrian rocks in the British Isles. Geological Society Special Report, No.6. p.52-75. Scottish Academic Press, Edinburgh. |
Bailey, E B and Maufe, H B, 1960. The geology of Ben Nevis and Glen Coe (Second Edition). Memoir of the Geological Survey of the United Kingdom. (Scotland, Sheet 53). |
Harris, A L, Haselock, P J, Kennedy, M J and Mendum, J R, 1994. The Dalradian Supergroup in Scotland, Shetland and Ireland. 33-53 in Gibbons, W E and Harris, A L (editors). A revised correlation of Precambrian rocks in the British Isles. Special Report of the Geological Society, London, No.22. |
Stephenson, D and Gould, D. 1995. British Regional Geology: the Grampian Highlands (4th edition). (London: HMSO for the British Geological Survey), 67-68. |
Treagus, J E and King, G, 1978. A complete Lower Dalradian succession in the Schiehallion district, central Perthshire. Scottish Journal of Geology, Vol.14, 157-166. |
1:50K maps on which the lithostratigraphical unit is found, and map code used: |
S019
S027
S045
S045
S053
S054
S054
S055
S055
S056
S063
S063
S064
S065
S065
S075
S075
S085
S085
S086
S095
S096
S044
S036
S062
S086
S096
S053
S046
|