reat wasting of the surface and solid parts of our
land, and the unequal degradation of this surface, by which means the
shape of the earth is so changed, that it would often be impossible,
from the present state, to judge of the course in which many bodies had
been travelled by water.

M. de Saussure has described a very curious appearance of this kind:
It is the finding the travelled materials of Mont Blanc, or fragments
detached from the summit and centre of the Alps, in such places as give
reason to conclude that they had passed through certain openings between
the mountains of the Jura. This is a thing which he thinks could not
happen according to the ordinary course of nature; he therefore ascribes
this appearance to some vast _debacle_, or general flood, which had with
great impetuosity transported all at once those heavy bodies, in the
direction of that great current, through the defiles of the Alps, or the
openings of those mountains.

In giving this beautiful example of the wasting and transporting
operations of this earth, this naturalist overlooks the principles which
I would wish to inculcate; and he considers the surface of the earth, in
its present state, as being the same with that which had subsisted while
those stones had been transported. Now, upon that supposition, the
appearances are inexplicable; for, How transport those materials, for
example, across the lake of Geneva? But there is no occasion to have
recourse to any extraordinary cause for this explanation; it must appear
that all the intervening hollows, plains, and valleys, had been worn
away by means of the natural operations of the surface; consequently,
that, in a former period of time, there had been a practicable course
in a gradual declivity from the Alps to the place where those granite
masses are found deposited. In that case, it will be allowed that there
are natural means for the transportation of those granite masses from
the top of the Alps, by means of water and ice adhering to those masses
of stone, at the same time perhaps that there were certain summits of
mountains which interrupted this communication, such as the Jura, etc.
through the openings of which ridges they had passed.

In this case of blocks of alpine stones upon the Jura, the question is
concerning the transportation of those stones; but, in other cases, the
question may be how those blocks were formed.

That many such blocks of stone are formed by the decay of t