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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



[Mar. 6, 



The continued researches that have been pursued of late years in 

 the Permian strata of Durham have carried our knowledge of their 

 palaeontology and geology much in advance of that of the Permian 

 formation of Britain generally ; and nowhere is the contrast greater 

 than with the Yorkshire portion of that formation, more particularly 

 in regard to its palaeontology : and it is with a desire to add 

 something to what we already know of the Permian strata of the 

 district specified that I make the following observations. The ex- 

 haustive investigations of Prof. Sedgwick, however, have left little to 

 add to the full account of the lithology of this district given in his 

 memoir ; so that I am obliged to confine my attention chiefly to its 

 palseontology. It is a delicate, and certainly a difficult, matter to 

 notice its geology at all after Prof. Sedgwick ; and I only clo so some- 

 what briefly in order to show how it would seem best to co-ordinate 

 the subdivisions of strata with those of the Durham series, and for 

 the sake of more fully explaining some of the facts relating to the 

 fossils. 



§ II. Permian District in South Yorkshire. — Before proceeding 

 further, it may be remarked that, in examining a geological map, the 

 Permian strata of Yorkshire are seen to traverse the centre of the 

 county in a long narrow stripe, running about N.N.W. and S.S.E., 

 apparently almost wearing out in the former direction, and gradually 

 increasing in width towards the south until a maximum of about five 

 miles is attained, at which width they continue into Nottinghamshire. 

 Their western boundary — most abty described by Sedgwick — usually 

 forms a well-marked escarpment, often of comparatively great eleva- 

 tion above the low-lying plain of the coal-measures to the west*. 

 Their eastern boundary, where they dip beneath the Triassic strata, 

 is more difficult of determination, being often masked by alluvium or 

 marsh-land. As the general dip of the strata is easterly, their order 

 of succession can easily be examined by passing transversely across 

 their outcrop. This I did repeatedly during my peregrinations in 

 this region, and always found the same sequence of beds. 



Sections near Doncaster. — In going west from the town of Don- 

 caster, which stands on the alluvium-covered western edge of the 

 New Bed Sandstone, the first rocks we meet with arc some thin flaggy 

 beds of Limestone, with occasional bands of red and green marls, 

 which, as a group, we readily recognize as the " Brotherton Beds " 

 of early geologists. After passing extensive quarries of this lime- 

 stone (which, by the sinking of wells and other artificial excavations, 

 is known to have a deposit of marl and gypsum at its base) we come 

 to an extensive series of thick and irregular beds of limestone of a 

 whitish or yellowish colour and a subcrystalline texture. These beds 

 form a group of much greater thickness than the preceding member, 

 and are described by Prof. Sedgwick under the name of the " Small- 

 grained Dolomite." Still further west we meet with a series of piso- 

 litie, cellular, arenaceous, and compact limestones, some of which are 

 fossiliferous. The lower beds of this latter group rest immediately 



* As at Bamborough Cliff, Ilooten Pagnell, and several other places, where 

 the prospect westward is most magnificent. 



