34 On the Geology of Northumberland and Durham, 



ing in a geological point of view ; not only from the great 

 number of strata passed through, but owing to the shafts, by 

 which the coal was won, being sunk on the south side of the 

 main dyke, and the coal obtained by a drift driven due north 

 through it. This mode of coming at the coal, I believe, was 

 adopted for the purpose of avoiding the water supposed to be 

 accumulated in the rents and fissures in the strata towards the 

 north, while the coal-field on the south side of the dyke was 

 known to have been drained, by the Heaton and other engines, 

 to the dip of the Gosforth mine. The true inclination of the 

 dyke, and the depth to which the strata have been depressed 

 by it, have never been so accurately ascertained as at this place; 

 and the following particulars, obtained on the spot, are to be 

 relied upon. The distance of the West Pit to the south brow 

 of the dyke is three hundred and fifty yards. The breadth of 

 the fissure, which is filled with soft blue metal (argillaceous 

 shale), having irregular pieces of white post (hard sand- 

 stone) imbedded in it, is four feet. The fissure hades towards 

 the north at an angle of 37°, and ranges nearly from east to 

 west. For the first three hundred yards from the pit, the strata 

 rise at a pretty uniform and moderate rate towards the north ; 

 they then begin to bend down, and continue to dip gently close 

 up to the fissure. — The following is the section of the beds 

 where they come in contact with the south side of the dyke. 



Feet. Inches. 



White post next the roof 1 



Blue metal 5 



Coal 9 



Thill (fire-clay) 2 



Coal 2 



Thill 3 5 



The height of the drift 7 9 



Immediately on the north side of the fissure the following 

 beds presented themselves : — 



Feet. Inches. 



Coal at the top of the drift 3 3 



Thill 8 



White post 3 6 



The height of the drift 7 5 



The high main coal was first cut at the distance of five hun- 

 dred and eighty-four yards from the pit, and it was here found 

 rising to the north at the rate of nine inches in a yard, or an 

 angle of 14-° with the horizon. The strata are here thrown 

 down to the north not less than one hundred and sixty fa- 



