I.—The Rocks of the Volcano of Rhobell Fawr

Abstract

The conclusions as to the stratigraphical relations of the volcano of Rhobell Fawr, north of Dolgelley, in Wales, which were arrived at by Mr. T. H. Holland and myself, have received kindly recognition from Sir Archibald Geikie in his Presidential Address to the Geological Society of London in 1891; and we may now consider that the great ring of Arenig volcanoes, Cader Idris, the Arans, Arenig Fawr, and Moelwyn, rose upon an area already shattered by sporadic Cambrian outbursts. After again visiting Rhobell Fawr in 1892, in company with Mr. Mervyn Marshall, I feel able to give some account of the rocks that build up that volcano and its outlying fort-like masses.