During this time of comparative rest, rhyolites were extruded locally in county Antrim; and there is very strong evidence that the granite of the Mourne Mountains, and that which cuts the Carlingford gabbro, were added at the same time to the crust.
We may note the pre-Cambrian lavas and tuffs of the Wrekin district in Shropshire and the somewhat later volcanic rocks of Charnwood; the porphyrites, andesites, tuffs and rhyolites of the Borrowdale volcanic centre, erupted in the Ordovician period, and the Silurian granites of the same region.
The Devonian rocks at Yalwal are sharply folded and are associated with a series of rhyolites and basic lavas.
The whole of this consists of tuffs and lavas, andesites prevailing in the west and rhyolites and dacites in the east.
Rhyolites were erupted locally near Tardree, Ballymena and Glenarm.