The BGS Lexicon of Named Rock Units — Result Details

Pen-Ychain Rhyolitic Complex

Computer Code: PCR Preferred Map Code: PC
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Rhyolitic domes, sills and tuffs associated with the Pitts Head Tuff and Llwyd Mawr Tuff.
Definition of Lower Boundary: Overlies sandstones, tuffs and siltstones of the Cwm Eigiau Formation.
Definition of Upper Boundary: Overlain by sandstones, tuffs and siltstones of the Cwm Eigiau Formation or ash-flow tuffs and breccias of the Lower Rhyolitic Tuff Formation.
Thickness: Up to 700m (including the Pitts Head Tuff).
Geographical Limits: Pwllheli area, northwest Wales.
Parent Unit: Snowdon Volcanic Group (SV)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Pen Ychain, near Pwllheli. 
Reference(s):
Young, T P, Gibbons, W and McCarroll, D. 2002. Geology of the country around Pwllheli. Memoir of the British Geological Survey, Sheet 134 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E134