Remarks upon the relations and grouping of the Permian and Triassic rocks / by Horace B. Woodward.

  • Horace Bolingbroke Woodward
Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: Remarks upon the relations and grouping of the Permian and Triassic rocks / by Horace B. Woodward. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    No. 9, September, 1874.] KEMAEKS UPON THE EELATIONS AND GROUPING OF THE PERMIAN AND TRIASSIC ROCKS. By Horace B. Woodward, F.G.S., Of the Geological Survey of England and Wales. The physical history of the Permian and Triassic rocks of Great Britain has been told by Professor Ramsay, who has pointed out that the beds were deposited in great inland lakes, for the most part salt.^ Without entering into the consideration of this subject, there seems to be much that requires to be unravelled in regard to the structure of the beds individually, and much that has yet to be explained in regard to the relations and grouping of the rocks. In their general lithological characters there is a marked simi- larity throughout the Permian and Triassic series, consisting as they do of red sandstones, conglomerates, and marls, with occasional beds of limestone. Originally, the whole of these rocks were classed as New Red Sandstone, and the name “ Poikilitic,” subsequently sug- gested by Conybeare, as an equivalent term, is one that possesses many advantages to recommend it. The ideas that as students we derive from our text-books are that the Permian beds form a group overlain unconformably by the Trias, and sufficiently distinct in their palaeontological aspect to be classed as Paleozoic; whilst the Triassic beds (classed as Mesozoic) are divided into Bunter and Keuper, and are regarded as equivalents of the same beds on the Continent—the Muschelkalk being considered to be absent in the British area, and the Keuper beds to rest unconformably upon the Bunter. The exact evidence upon which these ideas are based appears, however, to be conflicting when it comes to be examined into, and frequently to have but a very local signiflcance, as more recent re- searches have tended to show. It may therefore be interesting to draw attention to some of tbe points of the case, and to notice some of the later opinions expressed. The history of the researches into the Permian and Triassic beds has been given at length by Professor Hull in a work detailing the investigations of the Geological Survey in the midland counties of England: it will suffice therefore to refer to his Memoir* in regard to this part of the subject. * Quart. Journ. Geol. Soc., vol. sxvii. pp. 189, 241. I'ublished by tbe Geological Survey.