GEOLOGY OF PABT OF SOUTH DURHAM. 



185 



Intimately connected with 

 southern termination of the 

 coal-field is a series of great 

 dislocations, which traverse 

 the county in a general east 

 and west direction. The first 

 and most northerly of these is 

 the well known Butterknowle 

 "Dyke," which is a downthrow 

 to the south of from eighty to 

 over one hundred fathoms. 

 Near the outcrop of the Coal 

 Measures the course of the 

 fault is about east, but in tra- 

 versing the coal-field it soon 

 becomes gradually deflected to 

 the north until its direction is 

 nearly north-east. In the Eth- 

 erley district the throw appears 

 to be greatest to the east. At 

 Butterknowle it is from eighty 

 to ninety fathoms. At Ether- 

 ley, where it has been lately 

 proved, it is found to reach 

 one hundred and six fathoms ; 

 and a little to the north-east 

 of Coundon it is one hundred 

 and twelve fathoms. 



Less known than the Butter- 

 knowle fault is the great dislo- 

 location already mentioned as 

 having been proved at New 

 Copley Colliery, where it is 

 known as the Wiggle sworth 

 fault. The downthrow of this 

 dislocation is again to the 



fee 





■"ault, down 

 outh, 70-80 

 fathoms. 



