GEOLOGY 



As a whole it covers a tract ot country thirty-two miles long from east to west, and averaging 

 six miles in breadth. 1 To the north it runs out upon the Lower Coal Measures, to the south it dips 

 under a narrow band of Permian sandstones and marls, the whole being faulted down beneath the 

 Trias of the Cheshire plain, which extends into the margin of the coalfield in a few broad 

 triangular tongues. To the east, as to the north, the measures run out upon the Lower Series, 

 whilst to the west they are faulted down to a great depth under the Trias, which here forms a low, 

 flat maritime plain. 



Although it would thus appear that the coalfield is compact, yet faulting and denudation 

 have been so extensive that no complete correlation of the coal seams has yet been established. 



Whilst also some of the seams are fairly persistent, others thin or swell out, whilst hundreds of 

 feet of shale in one place are represented by a few feet of sandstone in another. 



It is possible that some of the thicker and more valuable coals are persistent over a great part of 

 the coalfield, being known under different names in different districts, and altering somewhat in their 

 character. The extreme east of the coalfield we may define as the 



(A) OLDHAM AND DUKINFIELD AREA 

 The best general section is that given by Professor Hull 2 and reproduced here. 



COAL SERIES OF OLDHAM AND MIDDLETON 



Bardsley Colliery 



Ft. In. 



The two sections are practically continuous, the interval between the base of the Bardsley 

 Colliery section and the Blenfire rock of Glodwick being occupied by a series of shales and sandstones. 



1 Hull's Coalfields of Great Britain, ed. 4 (1881), p. 197. 



3 'Geology of the Country around Oldham,' Mem. Geol. Survey, p. ^\, 1864. 



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