Two groups of rocks, designated as the Airy's Bridge group (2,500-2,850 feet) and the Lincomb Tarns formation (800 feet), have been mapped as welded tuffs occurring within the Borrowdale volcanic series, a 10,000-foot sequence of basaltic, andesitic, and rhyolitic flows and tuffs of Ordovician age in Cumberland, northwest England. The characteristics are described, and a chemical analysis is given. The deposition of welded tuffs is discussed. The occurrence of welded tuffs in Wales is mentioned.

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