Ch. XXL] SECTION OF WEALD VALLEY. 287 



superficial area occupied by each of the five formations above 

 mentioned. On the west will be seen a large expanse of chalk, 

 from which two branches are sent off; one through the hills of 

 Surrey and Kent to Dover, forming the ridge called the North 

 Downs, the other through Sussex to the sea at Beachy Head, 

 constituting the South Downs. The space comprised between 

 the North and South Downs, or e the Valley of the Weald,' 

 consists of the formations Nos. 2, 3, 4, 5, of the above table. 

 It will be observed that the chalk terminates abruptly, and 

 with a well-defined line towards the country occupied by those 

 older strata. Within that line is a narrow band coloured blue, 

 formed by the gault, and within this again is the Lower green 

 sand, next the Weald clay, and then, in the centre of the dis- 

 trict, a ridge formed by the Hastings sands. 



Section of the Valley of the Weald. It has been ascertained 

 by careful investigation, that if a line be drawn from any part 

 of the North to the South Downs, which shall pass through 

 the central group, No. 5, the beds will be found arranged in 

 the order described in the annexed section (No. 63, p. 288). 



We refer the reader at present to the dark lines of the 

 section, as the fainter lines represent portions of rock supposed 

 to have been carried away by denudation. 



At each end of the diagram the tertiary strata a are exhibited 

 reposing on the chalk. In the centre are seen the Hastings 

 sands (No. 5), forming an anticlinal axis, on each side of which 

 the other formations are arranged with an opposite dip. It has 

 been necessary however, in order to give a clear view of the 

 different formations, to exaggerate the proportional height of 

 each in comparison to its horizontal extent, and we have sub- 

 joined a true scale in another diagram (No. 61) in order to 

 correct the erroneous impression which might otherwise be 

 made on the reader's mind. In this section the distance 

 between the North and South Downs is represented to exceed 

 40 miles; for we suppose the valley of the Weald to be here 

 intersected in its longest diameter, in the direction of a line 

 between Lewes and Maidstone. 



