The BGS Lexicon of Named Rock Units — Result Details

Craighead Limestone Formation

Computer Code: CRDL Preferred Map Code: CRDL
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Massive limestone, with conglomeratic base resting on irregular surface of pillow lava.
Definition of Lower Boundary: Irregular unconformity on pillow lavas. The latter are possibly Balcreuchan Group (Arenig) but could be of much younger (Carodoc) age.
Definition of Upper Boundary: Not seen (faulted), but thought to be overlain by the Plantinhead Member of the Ardwell Farm Formation.
Thickness: To 90m
Geographical Limits: Area around the south and east side of Craighead Hill. Girvan, Ayrshire, Scotland.
Parent Unit: Ardwell Subgroup (AWL)
Previous Name(s): Craighead Limestone (-3955)
Alternative Name(s): none recorded or not applicable
Type Section  Craighead Quarry, 6km northeast of Girvan, Ayrshire, Scotland. Williams, 1962. 
Fortey, R A, Harper, D A T, Ingham, J K, Owen, A W, Parkes, M A, Rushton, A W A and Woodcock, N H. 2000. A revised correlation of Ordovician rocks in the British Isles. Geological Society Special Report, No.24. 
Williams, A, 1962. The Barr and Lower Ardmillan Series (Caradoc) of the Girvan district, southwest Ayrshire, with descriptions of the Brachiopoda. Memoir of the Geological Society of London, No.3. 
Murchison, R I. 1851. On the Silurian rocks of the south of Scotland. Quarterly Journal of the Geological Society of London, Vol.7, p.137. 
1:50K maps on which the lithostratigraphical unit is found, and map code used: