Ordovician (Caradoc) marginal basin volcanism in Snowdonia (north-west Wales) /
Howells, M. F.(Malcolm Fletcher)
Reedman, A. J.
Campbell, S. D. G.
British Geological Survey.
London : HMSO,
1991.
Prepared for the British Geological Survey.
Includes bibliography and index.
Volcanism
Volcanic ash, tuff, etc.
Geology, Stratigraphic