Soils are thus formed, either by the resolution of the surface of that land upon which they are to rest, or by the transportation of those solid parts to be again deposited upon another basis.  In this manner soils are constantly changing upon the same spot; sometimes they are meliorated, at other times impoverished.  From the tops of the mountains to the shores of the sea, all the soils are subject to be moved from their places, by the natural operations of the surface, and to be deposited in a lower situation; thus gradually proceeding from the mountain to the river, and from the river, step by step, into the sea.  Countries are thus formed at the mouths of rivers in the sea, so long as the quantities of materials transported from the land exceeds that which is carried from the shore, by tides and currents, into the deeper water.

The soil, with which the surface of this earth is always covered more or less, is extremely various, both with respect to quantity and quality; it is found resting upon the solid parts; and those solid parts are always more or less affected by the influences of the atmosphere near the surface of the earth.  Those parts of the strata which approach the surface are always in a decayed state; and this sometimes may be observed for very considerable depths, according as the quality of the materials, and the situation of the place dispose to that effect.  This general observation however may be formed, that, cet. par. the strata become always more solid, or are found in their sound and natural state, more and more in proportion as we sink into the earth, or have proceeded from the surface.

There is nothing of which we have more distinct experience than this, That, universally upon the surface of the earth, the solid parts are dissolving and always going into decay; whereas, at a sufficient depth below, they are found in their natural consolidated state.  The operations of man in digging into the ground, as well as the sections of the earth so often formed by brooks and rivers, affords such ample testimony of this truth that nothing farther need be observed upon this head only that this is a most important operation in the natural economy of the globe, and forms a subject of the greatest consequence in the present Theory of the Earth, which holds for principle, that the strata are consolidated in the mineral regions far beyond reach of human observation.

Consistently with this view of things, the strata or regular solid parts, under the soil or travelled earth, should be found in some shape corresponding to the represented state of those things, when affected by the powers which have acted upon the surface of the earth.  Here, accordingly, the strata are always to be observed with those marks of resolution, of fracture, and of separation, which have most evidently arisen from the joint operation of those several causes that have been now explained.  But though every operation of the globe be necessarily required for the explanation of those appearances which we now examine, it is principally the action of the sun and atmosphere, and the operations of the waters flooding the surface of the earth, that form the proper subject of the present investigation.