W. M. Mulchings — Clays, Shales, and Slates. 



309 



at the upper part of the cliff in a perpendicular position. These 

 are beyond a doubt effects of the same cause. Ou the lighthouse hill 

 at Cromer also, the chalk is forced up to the surface, 200 feet 

 above its natural level, and a limekiln is worked on the spot. 

 The valleys of Norfolk are such as are denominated ' valleys of 

 elevation ' ; that is, they were formed by the upheaving of the chalk 

 and its consequent fracture. This is demonstrated by the agree- 

 ment of the ' salient ' with the ' re-entering angles ' of their 

 borders, and from the fact of the layers of flint in the chalk, on each 

 side of the valley, being found to decline from its line of fracture." 

 In describing the general results of his inquiries, S. Woodward, 

 inter alia, urges that the chalk was disrupted subsequently to the 

 period when the great mammals lived in Norfolk, when, he argues, 

 this country was separated from the continent, at the same time 

 forming the valleys of Eastern Norfolk and the drainage of the 

 county. (Op. cit., pp. 6-9.) 



V. — Clays, Shales, and Slates. 

 By W. Maynard Hutchings, F.G.S. 



IN pursuance of my studies of clays, shales, and slates, I have 

 recently been examining some specimens to which a good deal of 

 interest attaches. Some of them are Carboniferous shales from deep 

 collieries in South Wales. Another, also a Carboniferous shale, is 

 from a deep boring in the Isle of Man. 



The object in view, in examining these specimens, was, in the 

 first place, to see how far they agree in general nature and 

 chemical composition with the very numerous Carboniferous clays 

 and shales which I have investigated from other districts. In the 

 second place, it was desired to see whether these shales from 

 considerable depths had made any perceptibly greater advance 

 towards becoming slates, than those derived from points very much 

 nearer the surface ; whether they were harder and more compact ; 

 and whether they showed a corresponding change in the nature 

 of their minei'als, or of the arrangement of these in the structure 

 of the rock. 



As regards the chemical composition, I have made the following 

 analyses. A is the deepest of the Welsh shales, from 1300 feet. 

 B is the specimen from the Isle of Man, but I do not know the 

 exact depth from which it was taken. 



A. B. 



