Mr. Buhdle's Notice of a Whin Dyke. 15 



From Walker Colliery the Dyke seems to run into South Hebburn ; 

 but it has not yet been discovered in any underground workings in that 

 colliery, nor in any other, to the South Eastward of Walker. Indeed, 

 no colliery workings, beyond Walker, have yet been extended far enough 

 in that direction, to intersect it ; and it is by no means improbable that 

 it resumes its ascent in Walker, on approaching South Hebburn, so as to 

 regain the surface at Simonside. 



It is worthy of remark, that the Basalt, in the Walker Dyke, is stated 

 to be 13 feet thick, being the same as we found it in Benwell Colliery. 

 From the quarry at Simonside being filled up, the thickness of the Ba- 

 salt there cannot be ascertained by inspection at this time ; but the men, 

 who worked it state that it crops out in Hedworth Burn, at which point 

 they commenced working. They followed it to some distance, probably 

 50 yards, in a North West direction, in which distance it thickened from 

 6 to 11 feet. It dipped considerably to the North West, which, on ac- 

 count of the influx of water, stopped their operations. 



From an examination of the map, and an attentive consideration of 

 all the foregoing circumstances, it will, I think, be admitted, that we 

 have strong grounds for concluding that the Dyke at Coley Hill, Mon- 

 tague Main, Benwell, Ouseburn, Lawson's Main, Walker, and Simon- 

 side, is the same ; and that it may probably extend to a much greater 

 distance, both to the South East and North West, than has yet been 

 traced, owing to its undulating structure. For, assuming it to be at, or 

 very near the surface at the Ouseburn, it does not again emerge to the 

 North West till it reaches Coley Hill, nor to the South East till it 

 reaches Simonside, the distance each way being five miles and a quarter. 

 So that, if we assume this to be the law of its undulations, the next ap- 

 pearance of the Dyke to the North West would be five miles and a 

 quarter further in that direction, and its next rising to the South East 

 would be under the sea. 



The greatest depth at which this Dyke has been found in Walker 

 Colliery is about 105 fathoms below the Tyne level, and at Benwell its 

 depth below the Tyne level is only between 30 and 40 fathoms ; but, 

 considering its depth relatively to the level of the seams of coal, taking 



