Geoscience Reference
In-Depth Information
Landscape B: The Wealden margin
South of the spectacular Chalk hills of the North Downs, there is a distinct belt of hills
formed because of the resistance to erosion of the Lower Greensand of Early Creta-
ceous age. The Greensand is rich in quartz grains held together by mineral cement,
and seems to have resisted erosion more effectively than the overlying and underlying
mudstones. In fact, the Greensand has resisted erosion so well in this Area that Leith
Hill (
b1
) has an elevation of about 290 m - distinctly higher than the Chalk hills of
the North Downs (Landscape
D
), which reach a height of only 173 m at Box Hill (
d4
).
The Greensand has again resisted erosion to the east of the River Mole, south of the
M25 and M26 motorways, and the resultant hills reach over 200 m in elevation south
of Sevenoaks.
FIG
199.
View from Westminster over central and eastern London, looking along the
Thames towards the sea. (Copyright London Aerial Photo Library)
