ation of caves, we would expect
them to occur in river valleys, and this is the case, though in some
instances there have been such immense changes in the surface level of
the country that we can now find no trace of rivers near them. This is
exactly similar to some gravel deposits, which, as we have seen,
are occasionally found where is now no running water. The most noted
caverns, however, are found high up on the banks of existing rivers. We
can not doubt that the rivers were the cause of the caves. But having
excavated their beds below the level of the then existing caves, they
ceased to flow in them, and left them to be occupied by savage animals
and the scarcely less savage men. But at times, swollen by floods, the
river would again assert its supremacy and roll its waters through its
old channels.

These floods would not only tear up and rearrange whatever _debris_
had already accumulated, but would introduce quantities of sediment and
animal remains. In some such a manner as is here pointed out (though
exactly how geologists are not agreed) caves were invaded, after being
long occupied by men or animals, by floods of water. In many cases the
evidence would seem to indicate that after such a visitation by water
the cave and its water-rolled and water-arranged contents were left to
silence, visited by neither man nor beast. In such instances stalagmitic
coverings would gradually form over the confused _debris,_ and in some
places acquire a thickness of several feet. In some instances several
such floors are found one above the other, pointing to a prolonged
period of usage, and then a quiet stage, in which the drip of falling
water alone broke the silence, and nature sealed up another chapter of
cave biography beneath the layer of stalagmite.

One of the most important caves of England is Kent's Cavern, before
mentioned. This cave was carefully explored under the direction of a
committee appointed by the British Association, and to show the care and
thoroughness of the work we need only state that this work occupied the
greater portion of sixteen years, and hence the results obtained may
be regarded as, in a general way, illustrative of the life of the cave
dwellers. "This cave is about a mile east of Torquay harbor, and is of
a sinuous character, running deeply into a hill of Devonian limestone,
about half a mile distant from the sea. In places it expands into large
chambers, to which various distinctive names h