Geoscience Reference
In-Depth Information
Figure 10.2 Geology of the Weald, southeast England, showing the
extension of the strata across the English Channel into France. Chalk
(2) forms the hills of the North and South Downs while older softer rocks
are exposed inbetween (from C. Lyell, Manual of Elementary Geology
(1855), p. 273).
he took the Wealden district for a very particular purpose: his opposi-
tion to the conclusions on the age of this area announced a year earlier
by Charles Darwin (Figure
10.3
) in the first edition of Origin of
Species.
In his book Darwin had set out the problem (in the text between
pages 285 and 286): picturing himself standing on top of the chalk
North Downs, Darwin could visualise the high anticlinal form of the
rocks that had once overlain the Weald district between the escarp-
ment on which he stood and the South Downs thirty miles further
south. The area was now of lower elevation than the Downs, but was
known since the days of John Farey to have once been an anticline
of folded rocks that extended across the English Channel into the
Bas Boulonnais district of France. Darwin wondered how much rock
must have been removed to produce its present-day physiographical
