Mr. N. Wood on the Geology of Northumberland, ^c. 319 



Fa. Ft. In. Fa. Ft. In. 



Brought forward, ... 11 34 2 9 



Hard White Sandstone, 2 3 



Black Plate, 3 3 



Shale, 2 3 



Grey Beds, 5 10 



Plate, 3 3 



4. Coal, Midgeholme Seam, 



Soft Thill, 







17 



1 



^ 



... 



... 



5 







... 



... 







6 





53 



3 



H 



These beds of Coal are of good quality, particularly the Midgeholme 

 Seam ; being Bituminous, or Coking, with beds of Clay Ironstone in the 

 sti'ata between the seams. As remarked with respect to the other detached 

 basins, this one is characterised by the absence of beds of Limestone above 

 the Coal, and by corresponding strata of Grit and Limestones underly- 

 ing the Measures ; which, together with the thickness of the seams of 

 Coal, and their similarity to the lower beds of the regular Coal Mea- 

 sures, prove their position in the series. 



It is somewhat singular that so narrow a strip, or tongue, of the Coal 

 Measures, should stretch to such a distance into the midst of the Moun- 

 tain Limestone ; for in no place does it exceed a mile in breadth, one- 

 half being probably the average width, and that interrupted and cut off 

 by all the ravines which cross the line ; while its length, from the great 

 body of the Coal Measures at Hedley Fell, is above 27 miles. This is 

 occasioned, as before explained, by the depression of the strata on the 

 north, or dip side of these Dykes, along the whole of their course. The 

 extent of the throw will, no doubt, vary in different parts ; but we find 

 the Millstone Grit, and upper beds of the Limestone, successively crop 

 out to the west, on the south or rise side of the Dykes. 



Throughout a great part of the course of these Dykes, as far west as 

 Stublick, they are common Slip Dykes ; but west of Whitfield they are 

 not only of that kind, but are accompanied by a Basaltic Dyke ; and at 



