The BGS Lexicon of Named Rock Units — Result Details

Drumwhirn Member

Computer Code: DRWN Preferred Map Code: notEntered
Status Code: Pending Upgrade
Age range: Courceyan Substage (CF) — Courceyan Substage (CF)
Lithological Description: A white-buff and yellow medium- to fine-grained, thinly planar bedded sandstone intercalated with finely laminated grey calcareous siltstone, calcareous mudstone, grey silty mudstone and rare thin non-marine, dolomitic muddy limestone ("cementstone").
Definition of Lower Boundary: The basal contact is faulted in the type area. The presence of grey silty mudstone and dolomitic limestone ("cementstone") interbedded with sandstone distinguishes this basal member of the Ballagan Formation from the underlying sandstone-dominated Kinnesswood Formation.
Definition of Upper Boundary: Mapped as a conformable contact on NS20SE in the Lindsaystone Burn section at (NS 2824 0080), but not actually exposed. Defined as the lithological change from yellow sandstone with grey silty mudstone to red-purple sandstone with conglomerate and pedogenic carbonate typical of the Lindsayston Burn Member.
Thickness: At least 275m at the type area, but the base is faulted. The unit is interpreted to be laterally variable in thickness.
Geographical Limits: On sheets Ayr 14W and Carrick 8W, NS20SE, part of NS30SW near Dailly, South Ayrshire. The full lateral extent of the unit is not yet confirmed.
Parent Unit: Ballagan Formation (BGN)
Previous Name(s): Basal Sandstone (-4007)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  In the hills east and south of Lindsayston Burn southeast of Dailly between Craig and Drumwhirn farms, and east of Whitehill Farm. Eyles et al., 1949; Floyd, 1999; Monaghan, 2004. 
Reference(s):
Monaghan, A. 2004. Geology of the Dailly area, Ayrshire. BGS Internal Report, IR/04/035. 
Eyles, V A, Simpson, J B and Macgregor, M C. 1949. Geology of Central Ayrshire. Memoir of the Geological Survey of Scotland, British Geological Survey, Sheet 14 (Scotland). 
Floyd, J D. 1999. Geology of the Carrick - Loch Doon district. Memoir for 1:50 000 geological sheets 8W and 8E (Scotland). [London: The Stationery Office for the British Geological Survey.] 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S014 S008