The summit of the granite pyramids of Mont-Blanc, the summit of the Breven, that of the Saleve[19], and of every little hillock upon the surface of the earth, attest this truth, that there is no other natural means by which this end may be attained.  It is true, indeed, that geologists every where imagine to themselves great events, or powerful causes, by which these changes of the earth should be brought about in a short space of time; but they are under a double deception; first with regard to time which is limited, whereas they want to explain appearances by a cause acting in a limited time; secondly, with regard to operation, their supposition of a great debacle is altogether incompetent for the end required.  How, for example, accumulate the debris of the Breven, as we have now seen, upon the summit of that mountain, by the force of running water?  But this is only one of a thousand appearances that proves the operations of time, and refutes the hypothesis of violent causes.

[Footnote 19:  See Part II. chap. 30.]

From the top of those decaying pyramids to the sea, we have a chain of facts which clearly demonstrate this proposition, That the materials of the wasted mountains have travelled through the rivers; for, in every step of this progress, we may see the effect, and thus acknowledge the proper cause.  We may often even be witness to the action; but it is only a small part of the whole progress that we may thus perceive, nevertheless it is equally satisfactory as if we saw the whole; for, throughout the whole of this long course, we may see some part of the mountain moving some part of the way.  What more can we require?  Nothing but time.  It is not any part of the process that will be disputed; but, after allowing all the parts, the whole will be denied; and, For what?—­only because we are not disposed to allow that quantity of time which the ablution of so much wasted mountain might require.

CHAP.  X.

The Theory illustrated with a view of the Valleys of the Alps.

Such is the summit of the Alps, a body wasting by the influence of the elements, slowly changing, but in actual decay.  This mass of granite is arrived at such a perfect state of degradation as leaves no trace of its original shape or height, from whence we might compute the quantity which has been lost, or time which had flowed in bringing about that event.  We are now to take a view of the valleys that are formed at the same time that the mountains are degraded.

To the valleys of ice succeed those formed by water upon the same principle by moving the hard materials procured from the summits.  Let us now begin at the bottom of one of those fertile valleys, and ascend, tracing the marks of time and labour in those operations by which the surface of the earth is modified according to the system of the globe.