Ch. XXI.] 
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 i 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. 
