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L. F. HARPER. 



In the colliery workings at Coal Oliff the following 

 instances were noted. 



CoaJ Cliff Colliery 



(a) A dyke ten inches wide intersects the Bulli coal seam 

 vertically, and on reaching the roof spreads out horizontally 

 as a sill, eight inches thick, having failed to pass into the 

 sandstone roof. 



About eight feet from the dyke, a fault with a downthrow 

 of eleven feet has thrown the sandstone roof opposite the 

 coal seam, thus preventing the sill from extending beyond 

 the coal. On the downthrow side of the fault the coal is 

 unaltered, and no sill rock is present. 



(b) In another portion of the same colliery, a dyke five 

 inches wide is seen occupying a fault plane, the amount of 

 displacement caused by the fault being twenty-one feet. 



(c) In the Metropolitan Colliery, a fault with a displace- 

 ment of over two hundred feet has been proved, which 

 resulted in No. 4 coal seam being thrown opposite No. 1. 



No. 1 seam consists of about twelve feet of coal absolutely 

 unaffected by volcanic agencies, whereas No. 4 is almost 

 totally destroyed by a sill up to seven feet in thickness, and 

 which has been driven on for approximately half a mile. 



