OX THE CIRCULATIOX OF UNDERGROUND WATERS. 59 



CoTlyhurst {near Manchester) type. 



These beds arc believed to have been formed contemporaneously with the 

 Enville group, but in a separate hydrographical basiu, separated from that of 

 Shropshire, Staffordshire, and Warwickshire by an east and west upheaval of 

 Lower Carboniferous rocks across the plain of Choshiro. 



The Lower Permian beds of South Lancashire have been worked out in 

 great detail by Mr. Binncy, E.R.S., who gives tho following sequence in 

 descending order : — 



'Red marls, with numerous bands of fossili- 



ferous limestone, worked at Astle3 r and 



Red Marls. -^ Bedford. At "Worsley this series attains a 



thickness of 131 feet, with fifty-two thin 



^ beds of limestone 131 feet. 



j . p ( Bright red sandstone, obliquely laminated, of 

 . , J \ uniform texture, seen at Collvhurst and at 

 Sandstone. j Sto(kj) oTt .... 1500 feet. 



On the southern edge of the Lancashire coalfield these beds are slightly 

 unconformable to the underlying Coal-measures between Manchester and 

 Sutton, allowing the reappearance of the "Spirorbis Limestone " at Whiston. 

 North of the coal-field the unconformity is much more marked ; at Skillaw 

 Clough, near Bispham, Roach Bridge on the River Darwen, near Plea- 

 sington Station on the Blackburn Railway, the Permian rests directly on 

 tho Millstone Grit ; and in the wide spread of Lower Permian Sandstone, 

 found by your Reporter to underlio the low drift-covered plain of Garstang, 

 between Preston and Lancaster, the underlying rocks are of Lower Toredale 

 age, as is also the case in the deep borings of tho Furncss district, on the 

 opposite side of Morecambe Bay, carried out by the Diamond Boring Company. 



There are a few wells in the Garstang Permian Sandstone, the deepest of 

 which is at Higher Crookey. 



In Cumberland the same series obtains, but is overlaid by the St.-Bees 

 Sandstone, so finely developed in the cliffs of that name, and referred by Sir 

 Roderick Murchison to Permian age, though formerly referred to the Trias. 

 The Collyhurst Sandstones are described by Prof. Harkness in the Yale of 

 Eden, under the name of " Penrith Sandstones," as attaining a thickness of 

 nearly 3000 feet. 



Durham type. 



In Durham and the north-cast of England the sequence is widely different. 

 That at Durham is described by Prof. King as follows : — 



G. Crystalline and Concretionary limestone. 



5. Brecciatcd limestone. 



4. Fossiliferous limestone. 



3. Magnesiau limestone. 



2. Marl slate. 



1. Lower Red Sandstone (with Coal-plants). 



