The BGS Lexicon of Named Rock Units — Result Details

Crugan Mudstone Formation

Computer Code: CRMU Preferred Map Code: CM
Status Code: Full
Age range: Rawtheyan Stage (OW) — Rawtheyan Stage (OW)
Lithological Description: Brown-grey and green siliceous mudstones.
Definition of Lower Boundary: Disconformally overlies the dark grey graptolitic mudstones of the Nod Glas Formation.
Definition of Upper Boundary: Not present in the area.
Thickness: 600m+
Geographical Limits: Area around Pwllheli, northwest Wales.
Parent Unit: Not Applicable (-)
Previous Name(s): Crugan Mudstones (-3329)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Crugan Lane Quarry, near Pwllheli. 
Reference(s):
Price, D, 1981. Ashgill trilobite faunas from the Llyn Peninsula, North Wales, UK. Geological Journal, 16, 201-216. 
Matley, C A, 1938. The geology of the country around Pwllheli, Llanbedrog and Madryn, southwest Carnarvonshire. Quarterly Journal of the Geological Society of London, Vol.94, 555-606. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E134