182 PROCEEDINGS OF THE GEOLOCHCAL SOCIETY. [Feb. 10, 



somewhat as shown in the accompanying section (fig. 2 ; see also map, 

 page 183). 



The Coal-measures on each side of the supposed Axis. — As there is 

 no evidence of any similar axis, we may suppose that the coal-field 

 extends from the northern flank of the Cheshire axis to the borders 

 of the Lancashire Coal-field on the north, which, with that of Flint- 

 shire on the west and Poynton on the east, must form one con- 

 tinuous sheet (see map). To the south of the axis the coal-measures 

 may also be supposed to stretch for a considerable distance, and to 

 be continuous with those of Denbighshire and North Staffbrdshire. 

 The southern limits of this coal-tract are in all probability very 

 irregular and indented, owing to the proximity of the ancient margin 

 of the Carboniferous area. Should the plains of Mid-Cheshire ever 

 be pierced in search of coal, which from the enormous thickness of 

 the overlying secondary rocks appears hopeless, care will be required 

 to avoid striking upon the rocks below the coal, in the line of the 

 antichnal axis and along the southern margin, indicated by the 

 lighter shading on the map. 



The Permian Beds on each side of the supposed Axis. — The exist- 

 ence of such an axis of elevation as is here indicated, formed at the 

 close of the Carboniferous period, and belonging to the ** Pen die 

 system " of flexures, serves, I think, to explain the difference in 

 the character of the Permian formation to the north and to the 

 south of such a line in a more satisfactory manner than any other 

 hypothesis. The elevation of the Lower Carboniferous rocks into 

 ridges, from which the coal-measures were swept away partly by 

 atmospheric, partly by marine, denudation, would produce a ridge, or 

 ridges, of land-surface dividing the Permian basin on the north from 

 that on the south. That the Carboniferous rocks were thrown into 

 such ridges flanking the Permian sea, is clear from the position of 

 the beds at the northern base of the Pendle range at Clitheroe. To 

 admit of this hypothesis, we are not required to adopt a specu- 

 lation which has no example in this part of the country ; while 

 it helps to solve the problem why the Permian beds on either 

 side of this ridge belong to two distinct types, the Salopian and the 

 Lancastrian. 



CoNCLTJSIOSr. 



In conclusion, I regard the axis under the Cheshire plain as 

 merely the prolongation of the Carboniferous barrier which sepa- 

 rated the Permian basin of the north of England from that of 

 the Midland counties and Shropshire. The barrier was apparently 

 prolonged towards the district of Charnwood Forest, where it was 

 composed of Cambrian rocks, and was formed for the most part of 

 Mountain Limestone, Yoredale beds, and Millstone Grit, on either side 

 of the barrier. The Permian formation itself gives evidence of the 

 proximity of land ; for on the north side the Magnesian Limestone 

 becomes deteriorated both in composition and thickness towards 

 Nottingham, and on the other the Permian beds along the skirts of 

 the Leicestershire Coal-field are evidently marginal representatives 



