A HISTORY OF LANCASHIRE 



POST-CARBONIFEROUS CHANGES 

 The causes which have operated in altering the character of the Lancashire Coal Measures 

 since their deposition are of three kinds, viz. flexures or folding, denudation, and faulting. 



FORMATION OF SYNCLINES AND ANTICLINES 



1. Careful mapping has shown that the whole of the Carboniferous system of Lancashire has 

 been thrown into a number of anticlines and synclines along a line running west of north and east 

 of south, the axes of the folds being north of east and south of west. This folding caused the 

 separation of the Burnley Coalfield from that of South Lancashire, the crest of the intervening arch, 

 ' the Rossendale Anticlinal,' being afterwards denuded down to the Millstone Grit Series. The 

 former field owes its preservation to the formation at this time of the Pendle Hill Range, in which 

 the lower beds are brought up again to the north of the coalfield in a line parallel to the Rossendale 

 anticlinal. 



The approximate age of this system of folds is indicated by the occurrence of Permian deposits 

 in the Pendle range lying upon the upturned and denuded edges of the Coal Measures, and even 

 overlapping on to the Millstone Grit.^ 



This evidence shows that the development was post-Carboniferous and pre-Permian, and that 

 denudation of the Coal Measures preceded the deposition of the Permian. 



2. The high ground on the east of the Lancashire Coalfield, in which the Millstone Grit Series 

 outcrops, owes its origin to a simple fold formed subsequently to those we have considered, and 

 developed along a north and south line. The fold as a whole gave origin to the Pennine chain of 

 hills now forming the main axis of elevation in the north of England. 



This huge fold cuts off the Lancashire Coalfield on the west from that of Yorkshire on the east. 

 That the two were formerly continuous is abundantly proved by the close correlation which can be 

 established between them, and the regularity of succession upon each side of the axis of upheaval. 



The age of this north and south flexure is not by any means clearly determinable. That it was 

 formed before the deposition of the Trias is proved by the latter lying upon the Lower Carboniferous 

 along the southern extremity of the Derbyshire hills,' but that it was post-Permian, as is supposed by 

 Professor Hull, rests upon the belief that a great anticlinal fault traversing Lancashire and contem- 

 poraneous in its development with the upheaval of the Pennine chain is older than a second fault 

 which it meets to the south of Staffordshire. The anticlinal fault fractures the Coal Measures, and 

 passes under the Trias in Staffordshire without fracturing them, but the second fault which it joins 

 fractures both. 



Immediately to the south of the Lancashire Coalfield the anticlinal fault is accompanied by a 

 parallel series, one of which, known as the ' Red Rock Fault,' throws in the Permian Sandstone 

 against the Carboniferous. 



If the anticlinal fault and the parallel system above mentioned are of the same age, as seems 

 most probable, it follows that the former, as well as the latter, is of post-Permian age ; and since the 

 anticlinal fault is directly connected with the upheaval of the Pennine Chain, the age of the latter 

 appears to be established as post-Permian and pre-Triassic. It would thus appear that the dominant 

 features of the topoL^raphy of Lancashire were determined by the formation of two systems of folds 

 and the denudation of their crests before the commencement of the Mesozoic. 



FAULTING 



3. The third change which was induced in the Lancashire Coal Measures was caused by the 

 great system of faults which strike across the coalfield from N.N.W. to S.S.E. That these are 

 post-Triassic is shown by their continuance into the Trias of the Cheshire plain. That they are 

 possibly post-Jurassic is assumed, because the continuity of deposition was not interfered with from 

 the top of the Trias to the close of the Jurassic so far as is known. The more important of these 

 faults will be dealt with under their respective districts. 



Oldham District 



Several faults start in the neighbourhood of Ashton-under-Lyne and range north-west as far as 

 Rochdale and Heywood, with downthrows of from 100 to 200 yards. Immediately to the east of 

 this district in the Millstone Grit country runs the great Pennine Fault, passing almost north and 

 south, and bringing up the Pendleside (' Yoredale ') shales against the Millstone Grits. 



1 Hull ' Observations on the Relative Ages of the Leading Physical Features and Lines of Elevation of the 

 Carboniferous District of Lancashire and Yorbhire,' Quari. Joum. Geol. Soc, xxiv. 323 (1868). 



2 Hull, op. cit., p. 329. 



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