THE PERMIAN FORMATION. 201 



THE PEEMIAN FOBMATION IN THE NORTH-EAST 

 OF ENGLAND, 



WITH SPECIAL PREFERENCE TO THE PHYSICAL CONDITIONS 

 UNDER. WHICH THESE ROCKS WERE FORMED. 



BY E. WILSON. F.G.S. 



(Continued from page 191.) 



Development of Calcareous and Sedimentary Members in opposite 

 (viz., North and South) Directions, (a) 

 The Magnesian Limestone attains its maximum development 

 in the extreme north. In South Durham vertical sections 

 have proved these rocks to exceed 600ft. in thickness, (b) "Where 

 most fully developed in Yorkshire, they are not more than 450ft. 

 In extreme South Yorkshire and North Notts they do not 

 materially exceed 150ft. or 200ft. ; and in the extreme Southen 

 portion of their range, through the latter county, we find these 

 dolomitic rocks, along with the other members of the Permian forma- 

 tion of the North-east of England, gradually fade away one after 

 another — going South. The Upper Magnesian Limestone disappears 

 near "Worksop. The Lower Magnesian Limestone rapidly attenuates 

 south of Mansfield, and eventually dies out near Nottingham. South 

 of Nottingham the Permian Kocks are absent at the surface, and 

 explorations for coal at various points in and South of the Trent 

 Valley, e.g., "Wilford Colliery sinking, and the Clifton, Highfields, 

 Chilwell, and Owthorpe borings, have conclusively shown that they 

 do not set in again further South, for at all these points the New Red 

 Sandstone has been found resting directly on Coal Measures. In 

 tracing the Magnesian Limestone southwards, we observe not only 

 that the group of rocks bearing that name gradually dies away as a 

 whole, but we also notice that the formation, which is almost wholly 

 calcai*eous on the North, becomes intercalated with sedimentary 

 deposits, and that the latter become relatively more and more 

 important the further south we go. In South Durham the 600 odd 

 feet of Permian rocks consist entirely of dolomitic limestone ; in 

 South Yorkshire there cannot be more than 200ft. or 300ft. of Lime- 

 stone ; in North Notts the maximum thickness of Limestone falls 

 short of 100ft. ; south of Mansfield the Lower Magnesian Limestone is 

 less than 50ft. in thickness ; at South Scarle the two Limestones 



(a) Professor Hull and others have supposed that in the North of England 

 a mutual replacement of calcareous and sedimentary deposits of Permian age 

 took place in an East and West direction, and that a sedimentary series in 

 Lancashire and Cumberland balance a calcareous series in Notts, Yorkshire, 

 and Durham. (See Q.J.G.S., vol. xxv., p. 176 ; Geol. Mag., 1879, p. 574 ; Jukes' 

 School Manual of Geology, Permian Formation.) This cannot be so, however 

 for there is abundant evidence to show that these East and West Permian 

 areas were physically disconnected. (See "Age of the Pennine Chain, "Mid. 

 Nat, vol. iii., pt. 1, 1880.) 



(b) Note.— 632ft. of Magnesian Limestone dolomites were passed through in 

 Castle Eden Colliery. 



