SUBTERRANEAN GEOLOGY OF SOUTH-EASTERN ENGLAND. 157
learn that various public-spirited persons interested in geology were
thinking of raising money to be spent in deep borings in this and
other counties to aid in solving this most interesting geological
problem. For as no person, society or corporation is likely to bore
in Essex with a view of getting a large supply of water from the
Lower Greensand, or cheaper coal than can now be obtained there,
subscriptions such as enabled the Sub-Wealden boring to be carried
on seem to be the only available resource.
But whatever additions may be made to our knowledge of the
subterranean geology of South-eastern England before the close of
the nineteenth century, and however feeble and imperfect our
present knowledge may seem to the geologists of the future, enough
has already been ascertained, as we have seen, to demonstrate the
general truth of Godwin-Austen's forecast, and to furnish a most
striking illustration of his geological knowledge and insight, and of
the economical importance which may sometimes belong to purely
scientific speculations.
As it is natural that the borings ending in Palaeozoic or Triassic
rocks should seem to possess much greater interest and importance
than those of equal depth which end in the middle of the Oolites,
it becomes the more necessary to point out the scientific value of
those at Chatham and Battle, which might otherwise seem simply to
show that Palaeozoic rocks are not to be met with at certain depths
in those localities. The great distances apart at which the outcrops
of particular formations may often be seen have tended to make
geologists forget the fact that as almost all the sedimentary rocks
have been formed in seas more or less shallow, the belts of ground
they occupy may be of no great width, though frequently of very
great length.8 It does not therefore follow that because the outcrop
of a particular formation is traceable for hundreds of miles in a
certain general direction, the belt of ground it underlies in the
direction of its dip need be very broad, apart from the existence of
ridges of older rocks like that beneath the Cretaceous beds around
London. It may be remembered that the Sub-Wealden and
Chatham borings alike ended in a Middle Oolite Formation, the
Oxford Clay. The distance between the two borings is only 32
miles, yet in that distance 1,840 feet of beds have disappeared,
though the bottom bed in each was the same Mid-Oolite rock, and
the Great Oolite—found at Meux's and Richmond—would in all
8 See "Island Life," by A. R. Wallace, pt. I, chapter vi.