Type Group Overlies Dwyfach Formation Named for Llanbedrog | Underlies Nod Glas Formation Primary tuffs | |
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Sub-units Yoke House Formation, Carneddol Rhyolitic Tuff Formation, Foel Ddu Formation, Penmaen Formation Other lavas, volcaniclastic sediments | ||
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 Llyn Peninsula where the strata are exposed.
Contents
Outcrops
This succession of rocks is exposed around the village of Llanbedrog and in a band stretching northwestwards inland.
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.
References
Llanbedrog Volcanic Group Wikipedia(Text) CC BY-SA