Sandstone, porphyry, and granite, succeed each other from the coast to a very considerable distance into the interior, on a N.W.line.

The light ferruginous dust that is distributed over the county of Cumberland, and which annoys the traveller by its extreme minuteness, to the eastward of the Blue Mountains, is as different from the coarse gravelly soil on the secondary ranges to the westward of them, as the barren scrubs and thickly-wooded tracts of the former district are to the grassy and open forests of the latter.
As soon as I began to descend to the westward it became necessary to pay strict and earnest attention to the features of the country through which I passed, in order to determine more accurately the different appearances which, as I was led to expect, the rivers would assume.

In the course of my examination I found, first, that the broken country through which I travelled, was generally covered with a loose, coarse, and sandy soil; and, secondly, that the ranges were wholly deficient in that peat formation which fills the valleys, or covers the flat summits of the hills or mountains, in the northern hemisphere.

The peculiar property of this formation is to retain water like a sponge; and to this property the regular and constant flow of the rivers descending from such hills, may, in a great measure, be attributed.

In New South Wales on the contrary, the rains that fall upon the mountains drain rapidly through a coarse and superficial soil, and pour down their sides without a moment's interruption.