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
Stratotypes:
Type Section  Craighead Quarry, 6km northeast of Girvan, Ayrshire, Scotland. Williams, 1962. 
Reference(s):
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. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S014