The BGS Lexicon of Named Rock Units — Result Details

Ardmillan Group

Computer Code: AMN Preferred Map Code: notEntered
Status Code: Full
Age range: Caradoc Series (O4) — Ashgill Series (OA)
Lithological Description: Turbiditic sandstone, siltstone and mudstone with conglomerate at its base. Lateral impersistence and occurrence of similar lithologies at different horizons cause difficulties with stratigraphy.
Definition of Lower Boundary: Drawn at the base of the Ballatchie Formation where blue grey nodular mudstone,siltstone,fine-grained sandstone and conglomerate rest conformably upon boulder conglomerate with matrix supported clasts of basalt, dolerite and gabbro of the Benan Conglomerate Formation.
Definition of Upper Boundary: Overlain unconformably by the Silurian Mulloch Hill Conglomerate Formation.
Thickness: c.2000m.
Geographical Limits: The Girvan area from Girvan south to Glen App.
Parent Unit: Not Applicable (-)
Previous Name(s): Ardmillan Series (-4429)
Ardmillan Group (Upper Part) [Obsolete Name And Code: See AMN] (AMNA)
Ardmillan Group (Lower Part) [Obsolete Name And Code: See AMN] (AMNC)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Girvan. 
Reference(s):
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. 
Lapworth, C, 1882. The Girvan Succession. Quarterly Journal of the Geological Society of London, Vol. 38, 537-666. 
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. 
Peach, B N and Horne, J. 1899. The Silurian Rocks of Britain, Volume 1. Scotland. Memoir of the Geological Survey of the United Kingdom. 
Ingham, J K, 1978. Geology of a continental margin 2: Middle and late Ordovician transgression, Girvan. "In" Bones, D R and Leake, B E. Crustal Evolution in North Western Britain and Adjacent Regions. Geological Journal Special Issue, No.10. p.163-176. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable