The BGS Lexicon of Named Rock Units — Result Details

Garvock Group [Obsolete Name And Code: See Arbuthnott-Garvock Group]

Computer Code: GKG Preferred Map Code: GVK
Status Code: Index Level
Age range: Lochkovian Age (DO) — Pragian Age (DP)
Lithological Description: Sandstone dominates, interbedded with clast-supported conglomerate with well-rounded boulders/cobbles/pebbles predominantly of psammite, quartzite and lava (abundant in NE Midland Valley and near Highland Boundary Fault). Siltstone and mudstone interbedded with the sandstone, eg in Strathallan. Interbedded andesitic lavas at Laurencekirk. Calcrete near top in many areas.
Definition of Lower Boundary: Diachronous, one of two markers being used, whichever is the stratigraphically higher. Top of thick pile of andesitic lavas in south-west (Ochil Volcanic Formation) and northeast (Montrose Volcanic Formation), where conglomerate or sandstone overlies lava with apparent conformity. In the Dundee area, taken at level of highest fine-grained horizon ("fish-bed") of the Dundee Formation, where this is overlain by sandstone. Diachronous, rising to higher levels towards the south-west.
Definition of Upper Boundary: At base of bright red, massive, poorly-sorted siltstone and silty sandstone of Cromlix Formation, overlying coarser-grained sandstone or conglomerate of Garvock Group. Locally diachronous in areas adjacent to Highland Boundary Fault where conglomerate interfingers with Cromlix Formation.
Thickness: Variable, 1500-1800m over much of crop, but thinning to about 1000m in the Laurencekirk area.
Geographical Limits: Northern Midland Valley, Arran to Stonehaven.
Parent Unit: Not Applicable (-)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Valley of Bervie Water and unnamed tributary. 
Reference Section  Banks of Allan Water between Bridge of Allan and Kinbuck. 
Type Area  Forfar-Brechin area. [See also type sections of component (Melgund, Finavon Conglomerate and Tanadice) formations (in type area) and others elsewhere.] 
Reference(s):
Allan, P A. 1940. The geology of the Highland Border from Glen Almond to Glen Artney. Transactions of the Royal Society of Edinburgh. Vol.60, p.185. 
Campbell, R, 1913. The geology of south-eastern Kincardineshire. Transactions of the Royal Society of Edinburgh, Vol.48, pp.923-960. 
Armstrong, M and Paterson, I B, 1970. The Lower Old Red Sandstone of the Strathmore Region. Report of the Institute of Geological Sciences No.70/12 
Westoll, T S. 1951. The vertebrate-bearing strata of Scotland. 18th International Geological Congress, London, 1948, Vol. 9, p. 5-21. 
Carroll, S, 1995. Geology of the Auchenblae District. British Geological Survey Technical Report. WA/95/80. 
Francis, E H, Forsyth, I H, Read, W A and Armstrong, M. 1970. The geology of the Stirling district. Memoir of the Geological Survey of Great Britain, Sheet 39 (Scotland). 
Armstrong, M, Paterson, I B and Browne, M A E, 1985. Geology of the Perth and Dundee district. Memoir of the British Geological Survey, Sheets 48W, 48E and 49 (Scotland). 108pp. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S067 S066 S013 S338 S038 S049 S030