On the Occurrence of Angular, Subangular, Polished, and Striated Fragments and Boulders in the Permian Breccia of Shropshire, Worcestershire, &c.; and on the Probable Existence of Glaciers and Icebergs in the Permian Epoch

Abstract

The sedimentary strata which contain the fragments of striated and polished rocks to which I am about to call attention belong to the inferior portion of that which has been defined as the “Permian Group” by Sir Roderick Murchison, the true geological horizon of which in England was first explained by Professor Sedgwick, in his celebrated memoir, “On the geological relations and internal structure of the Magnesian Limestone and the lower portions of the New Red Sandstone series,” &c. It is of the last-named division of this series that they probably form a part. The speciality of the subject of this memoir scarcely requires me to enter upon points connected with descriptive geology further than may be needful to explain the true position of the Breccias alluded to; and the detailed sections subsequently given, having that object in view, should therefore be considered chiefly as explanatory of the general relations of the subdivisions of the Permian and Bunter strata to each other. It is, however, proper to state that the general position of the Permian rocks skirting the coal-fields of North Wales, Coalbrook Dale, and Staffordshire was first indicated in Sir Roderick Murchison's Map, published in 1839. They are there coloured as Lower Red Sandstone with subordinate calcareous conglomerates; and their lower boundary he defined by the outcrop of the Coal, while the upper he shaded off into the New Red or Trias properly so called. The line of demarcation between the Permian and Bunter rocks has, however, lately been