Page:Australia, from Port Macquarie to Moreton Bay.djvu/27

 Facts such as these will appear almost incredible to the English, or even the Canadian agriculturist; several causes may be assigned for this more than ordinary richness in alluvial soils in some situations on the east coast of Australia. First, the more than ordinary quantity of renovating substances which have been deposited on them during heavy floods. For in those districts in which we find the most of this rich brush land, (the Illawarra country, the Williams and Paterson rivers which join the Hunter, and all the northern rivers), the mountain ranges are eminently formed, from their height, steepness, and narrow shelving ravines and gullies, to effect the rapid transportation of rain-water to the lower grounds; and as the Australian climate is characterised by long intervals of fine weather, followed by sudden and violent rains, the decayed vegetation on the ranges becomes desiccated and pulverized by the heat during the dry weather, or else is reduced to ashes by the frequent bush fires, and is therefore in a state most favourable for being easily washed away by heavy rains, and subsequently deposited on the alluvial lands.

The geological formation of the basins of different rivers in Australia, exercises also a most