The BGS Lexicon of Named Rock Units — Result Details

Asaphus Ash Formation

Computer Code: ASA Preferred Map Code: notEntered
Status Code: Pending Upgrade
Age range: Abereiddian Stage (O2) — Llandeilian Stage (O3)
Lithological Description: Silicified andesitic tuffs and agglomerates with interbedded mudstones and siltstones containing a rich shelly fauna, particularly trilobites
Definition of Lower Boundary: Data unavailable.
Definition of Upper Boundary: Data unavailable.
Thickness: To 25m
Geographical Limits: none recorded or not applicable
Parent Unit: Not Available (!)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
none recorded or not applicable
Reference(s):
Strahan, A, Cantrill, T C, Dixon, E E L and Thomas, H H. 1909. The Geology of the South Wales coalfield. Part 10. The country around Carmarthen. Memoir of the Geological Survey of England and Wales. [London: HMSO.] 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E229