and around the Warwickshire Coal-field. 551 



the shales, including two sheets of igneous rock. The Pre-Carbon- 

 iferous age of the igneous intrusions, which might have been inferred 

 from their absence in the Carboniferous rocks and abundance in the 

 Lower Silurian shales, is thus placed beyond doubt. 



On passing Merevale the lower beds of the Coal-measures again 

 thicken out rapidly, with the development of a pebbly sandstone at 

 the base as before. The best section of this basement bed is found 

 in the Baddesley Mineral Eailway, but it may be traced from Mere- 

 vale Brook to a little north of Waste Hill. 



Dosthill. 



While Professor Lapworth was investigating the neighbourhood 

 of Nuneaton and Atherstone, the igneous rocks of Dosthill, on the 

 opposite side of the Coal-field, were visited by Mr. W. J. Harrison, 

 F.G.S., with the result of finding that shales similar to those of 

 Atherstone occurred here also. 1 The shales are first seen where the 

 footpath to Dosthill intersects the road to the Ford. They are 

 immediately overlain by a pebbly sandstone which forms the base 

 of the Coal-measures, and which may be traced southwards along the 

 west side of the lane, through the churchyard and neighbouring farm- 

 buildings. Immediately to the south of the village this sandstone 

 thins rapidly out, and the coal-seams come nearly, if not quite, into 

 contact with the diorite. But after passing the most southerly of 

 the igneous rocks, this sandstone reappears. There is no good 

 section in it, but its course can be followed without difficulty across 

 the ploughed land. 



The shales are seen in the side of the high road a quarter of a 

 mile south of Dosthill ; in a small pit near Stockall Barn ; in the 

 side of the high road again near the word ' mill ' ; and lastly in the 

 brook which comes down from the Brick Works. 2 The dip is in all 

 cases towards the south-west, at angles varying from 20° to 40°, and 

 therefore in nearly the same direction as on the east side of the 

 Coal-field. The dip of the Coal-measures, on the other hand, is 

 towards the east, and generally at a high angle (from 50° to 80°), 

 so that the unconformity is most conspicuous. The shales are highly 

 altered grey and olive-coloured sandstones. No red beds are seen, 

 and at present no fossils except worm-tracks 3 have been found. 

 There is a strong resemblance, however, in these shales to the 

 Nuneaton and Atherstone beds, and there can be little doubt that 

 they also are of Lower Silurian age. 



The Base of the Coal-measures continued. 

 The nature of the evidence, on which the base of the Coal- 

 measures has been drawn upon the map (now for the first time), has 

 been given above. It has been shown that the actual base is formed 

 in some cases of a conglomeratic sandstone, with a considerable 



1 Geol. Mag. 1882, New Series, Dec. II. Vol. IX. p. 565. 



2 The position of the boundary fault of the New Ked Marl is marked in this brook 

 by a rubble of diorite resting against red and white clay. Lumps of a white siliceous 

 vein-stuff containing specks of galena may be picked out of the white clay. 



3 Harrison, Midland Naturalist, vol. viii. 1885. 



