176 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 10, 



notice here. All along the southern margin of the coal-field it con- 

 sists 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 thick- 

 ness in different localities is found to vary considerably, in pro- 

 portion 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 Purness 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 York- 

 shire f. 



In the '' Lower Sandstones " of Penrith, estimated by Professor 

 Harkness to attain a thickness of 5000 feet J, 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, YorTcshire, and Nottinghamshire. — It is not within the 

 scope of this paper to refer to the Permian formation of the North- 

 east 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 meri- 

 dional 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. 

 t Quart. Journ. Geo! 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- 



