n a hard state, there appears
no reason why any connexion should be apparent between the energy of
_undulation_ and these _broken_ rocks. If the continuous waves were
caused by convulsive movements of the earth's surface while its
substance was pliable, and were left in repose for so long a period as
to become perfectly hard before they were broken into cliffs, there
seems no reason why the second series of shocks should so closely have
confined itself to the locality which had suffered the first, that the
most abrupt precipices should always be associated with the wildest
waves. We might have expected that sometimes we should have had noble
cliffs raised where the waves had been slight; and sometimes low and
slight fractures where the waves had been violent. But this is not so.
The contortions and fractures bear always such relation to each other as
appears positively to imply contemporaneous formation. Through all the
lowland districts of the world the average contour of the waves of rock
is somewhat as represented in Fig. 16 _a_, and the little cliffs or
hills formed at the edges of the beds (whether by fracture, or, as
oftener happens in such countries, by gradual washing away under the
surge of ancient seas) are no higher, in proportion to the extent of
surface, than the little steps seen in the centre of the figure. Such is
the nature, and such the scale, of the ranges of hills which form our
own downs and wolds, and the French coteaux beside their winding rivers.
But as we approach the hill countries, the undulation becomes more
marked, and the crags more bold; so that almost any portion of such
mountain ranges as the Jura or the Vosges will present itself under
conditions such as those at _b_, the precipices at the edges being
bolder in exact proportion to the violence of wave. And, finally, in the
central and noblest chains the undulation becomes literally contortion;
the beds occur in such positions as those at _c_, and the precipices are
bold and terrific in exact proportion to this exaggerated and tremendous
contortion.

[Illustration: FIG. 16.]

Sec. 21. These facts appear to be just as contrary to the supposition of
the mountains having been formed while the rocks were hard, as the
considerations adduced in Sec. 15 are to that of their being formed while
they were soft. And I believe the more the reader revolves the subject
in his thoughts, and the more opportunities he has of examining the
existing fact