44 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Nov. 2, 



section at " Success Engine Pit," given in Mr. Poole's tables, well 



illustrates this and the preceding head. ft. in. 



Black carbonaceous sbale, with bands of clay ironstone... 64 10 

 Main coal seam, including 23 inches of ironstone, in five 



bands 3!) 11 



Black carbonaceous shale, with bands of ironstone 157 7 



Deep coal seam, including one band of ironstone 141 



inches in thickness 24 9 



287 1 



In addition to this great thickness of argillaceous and carbonaceous 

 beds, several hundreds of feet of black shales are seen to overlie 

 them, in the sections afforded by the East lUver and road-cuttings. 

 Erect trees are not known to occur in these beds ; but flattened trunks 

 of Siffillaria, Favulm'ia, and Stigmaria, and Flabellaria and Fern 

 leaves occur in the shales. There are also evidences of submergence 

 during a part of the time occupied in the accumulation of these beds. 

 Teeth and bones of fishes are found in the roof of the deep seam ; 

 remains of large holoptychioid fishes occur in one of the bands of 

 ironstone in the main coal ; and a considerable thickness of the black 

 shale overlying the main seam is filled with the minute crustacean 

 valves of a species of Cypris or Cythere. 



4. There is an apparent unconformability of the coal and its asso- 

 ciated beds with the members of the coal-formation immediately suc- 

 ceeding it in ascending order. The main coal dips to N. 45° E. at 

 the Dalhousie Pits, and its outcrop is, as represented on the Plan, 

 curved, the convex side being towards the dip. The first beds of • 

 sandstone that occur in ascending order appear to have a strike nearly 

 E. and W., and dip to the north, at least in a part of their course. 

 Thus at the quarry nearly north of the Dalhousie Pits, the sandstone 

 dips nearly N.E., and is separated from the coal by a great thick- 

 ness of shale ; but westward of this point its outcrop approaches that 

 of the coal, and at length, at the distance of about 1 180 yards west 

 of Dalhousie Pit, it approaches within a few yards of the outcrop of 

 the main seam, and overlies its roof-shales w4th a higher and more 

 northerly dip. See trial-holes, Nos. 15, 22, and 29 ; in the last of 

 these the sandstone is stated to dip N. 30°, while the shale imme- 

 diately below dips N. 20°, E. 22°. (See also Plan.) 



At the " Colin Pits" this sandstone is worm-tracked, and presents 

 other marks of littoral origin. 



To account for the apparent Avant of uniformity in the dip of the 

 sandstone and underlying coal-measures, and in the direction of their 

 lines of outcrop, it seems necessary to suppose some degree of false 

 stratification in the sandstone, and that a portion of the shale was 

 removed by denudation before its deposition ; or that during the de- 

 position of the shale, a portion of the coal-field had subsided so as to 

 allow a great thickness of shale to be accumulated over a portion of 

 the coal, while another part was but thinly covered ; or that the beds, 

 which in the eastern part of the coal-field are wholly argillaceous, 

 became very rapidly arenaceous in their continuation westward. In 



