The BGS Lexicon of Named Rock Units — Result Details

Gartartan Conglomerate Member

Computer Code: GACO Preferred Map Code: GCO
Status Code: Full
Age range: Early Devonian Epoch (DL) — Early Devonian Epoch (DL)
Lithological Description: A poorly sorted, matrix supported, planar bedded, conglomerate with clasts of quartzite, quartz and igneous lithologies.
Definition of Lower Boundary: A sharp contact with the purple and reddish-grey, sublithic sandstone of the undivided Ruchill Flagstone Formation.
Definition of Upper Boundary: A sharp contact with the Cromlix Mudstone Formation, which comprises a poorly sorted silty sandstone around Gartartan, commonly with a thin conglomerate bed 30 - 40 m above the junction. North-eastwards, basal Cromlix beds exhibit a transition to a fine-grained, massive, well-sorted sandstone, eg; at Over Shannochil [NS 5428 9930].
Thickness: From 20 - 25 m between Gartmore House and Shannochill, increasing to 100 m thickness at Lochan Balloch [NN 592 043].
Geographical Limits: Gartmore to Lochan Balloch, north-east of which it virtually coalesces with Ben Dearg Conglomerate to form A'Chrannach Conglomerate (lower leaf) near Callander.
Parent Unit: Ruchill Flagstone Formation (RLF)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Outcrop 100m west of Over Shannochill Farm. 
Type Section  Roadside section on A81 beside Gartartan Cottage. 
Reference(s):
Browne, M A E, Smith, R A and Aitken, A M. 2001. A lithostratigraphical framework for the Devonian (Old Red Sandstone) rocks of Scotland south of a line from Fort William to Aberdeen. Version 3. British Geological Survey Research Report RR/01/04. 
Phillips, E R and Aitken, A M. 1998. The petrology and composition of the Lower Old Red Sandstone exposed in the Aberfoyle Area (Sheet 38E), Central Scotland. British Geological Survey, Technical Report, WG/98/10. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S038