our rocky coasts and
rivers will satisfy the enlightened observator of this truth; and to
endeavour to prove this to a person who has not principles by which to
reason upon the subject, or to one who has false principles, by which he
would create perpetual stability to decaying things, would be but labour
lost.

In proportion as the solid bulwark is destroyed, so is the soil which
had been protected by it; and, in proportion as the solid parts of the
mass of land are exposed to the influences of the atmosphere and water,
by the ablution of the soil, more soil is prepared for the growth of
plants, and more earth is detached from the solid rock, to form deep
soils upon the surface of the earth, and to establish fertile countries
at the mouths of rivers, even in making encroachment on the space
allotted for the sea. But this production of land, in augmentation of
our coasts, is only made by the destruction of the higher country.
While, therefore, we allow that there is any augmentation made to the
coast, or any earthy matter travelling in our rivers, the land above the
coast cannot be stable, nor the constitution of our earth fixed in a
state which has no tendency to be removed.

M. de Luc, in his Histoire de la Terre, would make the mountains last
for ever, after they have come to a certain slope. He sums up his
reasoning upon this subject in these words: "L'adoucissement des pentes
arrete d'abord l'effet de ces deux grandes causes causes de destruction
de montagnes, la _pesanteur_ et les _eaux_: la vegetation ensuite arrete
l'effet de toutes les petites cause."

If all the great and little causes of demolition are arrested by the
slope of mountains and the growth of plants, the surface of the earth
might then remain without any farther change; and this would be a fact
in opposition to the present theory, which represents the surface of the
earth as constantly tending to decay, for the purpose of vegetation,
and as being only preserved from a quick destruction by the solid rocks
protecting, from the ravages of the floods and sea, the loose materials
of the land. It will therefore be proper to show, that this author's
argument does not go to prove his proposition in the terms which he has
given it, which is, that those sloped mountains are to last for ever,
but only that these causes, which he has so well described, make the
destruction of the mountains become more slow[9].

[Footnote 9: This also would appear to be a