The Aran Volcanic Group is a geological group in Wales. It preserves fossils dated to the Ordovician period.[1] It is laterally equivalent with sedimentary rocks of the Ogwen Group, parts of which are interbedded with it.[2]

Aran Volcanic Group
Stratigraphic range: Ordovician
TypeGroup
Sub-unitsAran Fawddwy Formation, Benglog Formation, Brithion Formation, Craig Cau Formation, Craig y Ffynnon Formation, Cregennen Formation, Llyn y Gafr Volcanic Formation, Melau Formation, Offrwm Volcanic Formation, Pen-y-gadair Volcanic Formation, Pistyllion Formation, Rhiw Bach Volcanic Formation
UnderliesCeiswyn Formation
OverliesMawddach Group, Rhobell Volcanic Group
Thicknessup to 2.5 km
Lithology
PrimaryBasalt, Rhyolite, Volcaniclastics and Sedimentary rock
Location
CountryWales
ExtentHarlech Dome
Type section
Named forAran mountain range

See also

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References

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  1. British Geological Survey. "Aran Volcanic Group". BGS Lexicon of Named Rock Units. Retrieved 20 May 2025.
  2. Rushton, A.W.A.; Howells, M.F. (1999). "Stratigraphical framework for the Ordovician of Snowdonia and the Lleyn Peninsula" (PDF). British Geological Survey Research Report. Retrieved 21 May 2025.