On the Triassic Rocks of Somerset and Devon

Abstract

I ntroduction . T he Triassic areas of Devon and Somerset may be divided into three lithological districts:—the first, on the north and north-east of the Polden Hills; the second, on the north-east, east, and south-east of the Quantocks; the third, comprising the rest of the Triassic area, lies between Watchet and the south coast of Devon, being bounded on the west by the Devonian and Culmiferous highlands, and on the east by the Quantock and Blackdown ranges. The first of these districts is too well known to call for more than a general description in this place. In the Geological-Survey Memoir on the Bristol Coalfield it has been already treated of, the labours of Conybeare and Phillips, De la Beche, and the late Mr. Wm. Sanders, with those of Messrs. Moore and Etheridge having left little to be desired as far as the description of the Triassic strata is concerned. With reference to the last-mentioned districts, of which we purpose to give a more detailed though far from exhaustive description, it is different, the relations of the Trias not having been before established, except so far as might be inferred from a study of the splendid section along the coast between Seaton and Torquay. Sir Henry De la Beche, in his report upon the geology of Devon and Cornwall, gives a very general description of the Trias, without attempting a classification of its component marls, sands, and conglomerates, which the greater time occupied in the resurvey of the district has enabled me