The Llanbedrog Volcanic Group is an Ordovician lithostratigraphic group (a sequence of rock strata) in northwest Wales. The name is derived from the village of Llanbedrog on the Llŷn Peninsula where the strata are exposed.http://www.bgs.ac.uk/Lexicon/lexicon.cfm?pub=LIG (BGS on-line lexicon of rock units)
Outcrops This succession of rocks is exposed around the village of Llanbedrog and in a band stretching northwestwards inland.British Geological Survey 1:50,000 scale geological map (England & Wales) sheet 134 Pwllheli
Lithology and stratigraphy The Group represents an assemblage of both volcanic rocks - lavas, tuffs, breccias - and volcaniclastic sediments - mudstones, siltstones, sandstones and conglomerates. It comprises (in descending order i.e. youngest first) the Yoke House Formation, the Carneddol Rhyolitic Tuff Formation, the Foel Ddu Formation and, at its base, the Penmaen Formation.
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