Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/270

 notice here. All along the southern margin of the coal-field it consists of red calcareous marls and earthy limestones, with fossils of Permian genera, resting on the Lower Red Sandstone. At Leigh, west of Manchester, these beds have been proved by borings to reach 131 feet in thickness, with 52 courses of limestone ; but their thickness in different localities is found to vary considerably, in proportion to the amount of overlapping of the Bunter Sandstone. At Stockport this overlapping is so great that the conglomerate beds of the Bunter rest directly on the Lower Permian Sandstone itself.

At Skillaw Clough, near Ormskirk, the occurrence of Magnesian Limestone in the upper member of the formation introduces a more typical feature into the succession of the beds, such as they present near Furness Abbey and Barrow Mouth, as described by Mr. Binney*, and enables us to recognize in them the representatives of the great calcareous formation of Durham, Yorkshire, and Notts. Mr. Kirkby, on palaeontological evidence, refers the upper member of the Permian series in South Lancashire to the " Lower Limestone " of Yorkshire†.

In the "Lower Sandstones " of Penrith, estimated by Professor Harkness to attain a thickness of 5000 feet‡, we have the apparent representative of the Lower Permian Sandstone of south Lancashire, but more fully developed in a northerly direction, as is usually the the case with sandstone rocks of the Triassic and Permian ages in this part of England.

Durham, Yorkshire, and Nottinghamshire. — It is not within the scope of this paper to refer to the Permian formation of the Northeast of England, except to point out the relationship of this series of beds to those of the midland counties and Lancashire, as far as regards original deposition. I will therefore only remark that, as regards their relations to the Lancashire series, though so different in mineral character, they really belong to the same type. Here we have the development of the calcareous member on the one hand, and of the sedimentary member on the other, being an illustration of the law of development, in opposite directions, of calcareous and sedimentary strata, which I believe may be observed in the case of all natural groups of rocks. And as it has been shown in a former paper that the elevation of the Carboniferous rocks along the meridional axis of the Pennine chain has taken place since the Permian period, there is every reason to suppose that the Permian beds, both on the North-west and North-east of England, were deposited within the limits of the same hydrographical basin, and that there was a gradual variation of mineral character taking place across the North of England. This view seems to be held by Mr. Kirkby with reference to the Upper Permian series§ in both districts.


 * Mem. Lit. and Phil. Soc. Manchester, vol. xii. pp. 45, 46.

† Quart. Journ. Geol. Soc. vol. xvii. p. 320.

‡ Ibid. vol. xviii. p. 210.

§ Quart. Journ. Geol. Soc. vol. xvii. p. 321. Mr. Kirkby remarks, "The fauna of the Lancashire area appears to have existed on the argillaceous and semical-