﻿286 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



[Mar. 6, 



to make a ferruginous sandstone ; and occasionally clay-ironstone is 

 seen. Lignite is found in the sandy beds, either in small fragments 

 scattered through a sandstone or loam, or in a bed, from a fraction 

 of an inch to a foot or more thick, which does not continue for very 

 many yards ; and, again, there may be carbonaceous matter diffused 

 through a layer of loam or of clay. Loam occurs in large quantities 

 in the sandy beds ; it is in beds some feet thick, interstratified with 

 the sandstone ; the two substances interchange along the same stra- 

 tum-level, the beds varying very much within short distances. I 

 think that few continue for long of the same character, so as to be 

 recognized. Figs. 3 and 4 are two sketches of sections which show 

 plainly how the changes take place, either by the thinning off of a bed 



Fig. 3. — Section in the Tunbridge Wells Sand, near Strawberry Hill, 

 Tunbridge Wells. 



a, a. Sand in lamince. b. White Sandstone, 3£ feet. c, c. Sandstone, 

 fig. 4. — Section in the Ashdown Sand, at Biverhall, near Frant. 



a. Kock-sand. b. Loam in lamina;. c. Sandstone. d. Shaly Sandstone. 



and the wedging in of a new one, or by the overlying beds lapping 

 over its edge and occupying what would be its place if it were con- 

 tinued. 



Lastly, the sand often shows oblique lamination in different di- 

 rections ; and it probably was accumulated in that way in other 

 cases where there are no signs of it from the deposit being homo- 

 geneous. Ripples, too, are frequent, often well-marked, and striking 

 in various ways. 



But notwithstanding these changes, it holds good that the beds 

 which, on the whole, are sandy, and the beds that are chiefly of clay, 

 lie in the order which 1 have described, as represented in the section, 

 fig. 1, p. 276. 



