286 Mr. M. Dunn's Notice on the 



sketch, Plate XIV., Fig. 2, leaving the drift 4 feet 3 inches high, and 4 

 feet wide, the intermediate space A being for air-way and strength. The 

 process was carried on by horizontal piling, followed up by close timbering ; 

 and after the bottom-stone disappeared the flooring was also close planked ; 

 without going further into detail, we pursued the drifting through Gravel, 

 Quick-sand, and water, to the distance of 82 yards, Avhen we found it ex- 

 pensive and impracticable, and, moreover, without any signs of coming to a 

 termination. At intervals the drifting was interrupted by large gushes of 

 water and sand, which, together with a most severe pressure, alarmed us 

 not only for the safety of the drift, but also of the colliery ; so that at the 

 above distance we abandoned the attempt on the 1st October, 1832. 



The sketch, Plate XIV., Fig. 3, will shew the arrangement of the metals 

 passed through in the drifting. 



A box of specimens accompanies this notice, exhibiting several varieties 

 of rounded fragments which do not belong to the neighbourhood, and which 

 tend to shew that this was once the bed of a rivulet or lake, and that many 

 of the specimens have been rolled from afar. 



It may perhaps be worth mentioning that in the neighbourhood of the 

 Barras Bridge, Newcastle, where the said High Main Coal has cropped out, a 

 similar Gravel formation exists to a very considerable extent, but we have no 

 evidence that it is connected with that at Saint Lawrence, although in the 

 same line of country, and upon the same rivulet. 



With regard to the extent of this Gravel Bed we are ignorant, fur- 

 ther than the proofs we have gone into at Saint Lawrence, in the working 

 of the Colliery, and having bored down upon it at the west side of the 

 Ouseburn at A, therefore we have no doubt that the Main Coal is entirely 

 displaced throughout that extent ; but we have reason to believe that it ter- 

 minates shortly to the westward, where the coal is ascertained to be covered 

 by a very thick stratum of clay. There have been sinkings and borings in 

 the neighbourhood of the Lead Factory, further up the burn, but no 

 symptoms of Gravel. 



There is no reason to believe that the lower seams are at all affected by 

 the Gravel, as we are now prosecuting the Low Main Seam, under the part 

 B, without any such symptoms. 



