Character of the soil connected with geological formation.

From what has been advanced, however, it will appear that the physical structure of the southern parts of the colony is as varied, as that of the western interior is monotonous, and we may now pursue our original observations on the soil of the colony with greater confidence.

In endeavouring to account for the poverty of the soil in New South Wales, and in attributing it in a great degree to the causes already mentioned, it appears necessary to estimate more specifically the influence which the geological formation of a country exercises on its soil, and how much the quality of the latter partakes of the character of the rock on which it reposes.  And although I find it extremely difficult to explain myself as I should wish to do, in the critical discussion on which I have thus entered, yet as it is material to the elucidation of an important subject in the body of the work, I feel it incumbent on me to proceed to the best of my ability.

I have said that the soil of a country depends much upon its geological formation.  This appears to be particularly the case in those parts of the colony with which I am acquainted, or those lying between the parallels of 30 degrees and 35 degrees south.  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.  The consequence is that on such occasions the rivers are subject to great and sudden rises, whereas they have scarcely water enough to support a current in ordinary seasons.  At one time the traveller will find it impracticable to cross them:  at another he may do so with ease; and only from the remains of debris in the branches of the trees high above, can he judge of the furious torrent they must occasionally contain.