A HISTORY OF LANCASHIRE 



St. Helen's (continued) 



Wigan (continued) 



of poorer quality and contain dirt bands. 



Northwards of St. Helens, a great slice of the Middle Measures is cut out by the great Up- 

 Holland Fault, which has a throw of 700 yards. This fault, like all great faults in the Lancashire 

 area, ranges approximately N.N.W. and S.S.E., and is roughly parallel to the Irwell Valley Fault 

 already mentioned. It brings in the Lower Coal Measures on its eastern side. 



(D) BURNLEY COAL FIELD 



This area of Middle Coal Measures is surrounded by the lower series and overlaid by Glacial 

 drifts, no upper series being present. The best section obtainable is that of Fulledge, which, omitting 

 detail, is as follows : 



FULLEDGE SECTION 



Ft. 



77 

 3 

 23 



2 



62 

 2 



44 

 4 

 116 



2 



9 6 

 2 



Strata 



Low Bottom Coal 



Strata 



Cannel 



Strata 



Fulledge Thin Bed Coal 



Strata 



Great Mine Coal . . . 



Strata 



China Bed Coal . . . 

 Strata, with thin coal . 

 Dandy Bed Coal . . . 



Strata 



Arley Mine Coal . . . 

 Neglecting thin coals, the section shows about 40 feet of coal lying in a dozen seams. Of 

 these, the Arley Mine is most valuable and has the greatest development, outcropping around the 

 whole Coalfield. One seam, the Californian or Thin Bed, possesses a strong shale roof which 

 is remarkably fossiliferous, no less than 26 species being recorded from it, most of which are fishes. 



When surveying the Burnley Coalfield prior to 1874, Professor Hull calculated the Arley 

 Mine to have an area of about 23 square miles. Allowing 5,000 tons per acre, he estimated 

 the total yield as 73,600,000 tons, of which about one-tenth had been extracted, leaving, after 

 deduction for loss and waste, 65,000,000 tons to be mined in the future. 1 The total yield 

 to 1874 of the whole coalfield was estimated at 18,500,000 tons, leaving 89,000,000 tons 

 to be mined. 8 



1 'Geology of the Burnley Coalfield,' Mem. Geol. Survey (1875), P- 7$. 

 8 Op. tit., p. 83. 



18 



