386 PHYSICAL STRUCTUEE A?fD GEOLOGY OF AI'STEALIA, 



gentle elevation, the tracts available for agi-iculture are consider- 

 able. Towards the north of a line parallel with the head of St. 

 Vincent's Gulf, the rainfall is small and uncertain, which renders 

 proprietors, both agricultural and pastoral, subject to great losses 

 from drought. The geological age of this range has never been 

 exactly ascertained. It is undoubtedly paleozoic, but so singularly 

 destitute of fossils throughout its whole extent that nothing 

 more definite can be stated. 



New South Wales and Queensland are relatively in the same 

 position with reference to the table land. The capitals of the 

 colonies are built on the slopes between the plateau and the sea. 

 The portions of the upper part of the high lands included in both 

 colonies have much of the volcanic areas of great richness. The 

 lower lands are poor and sterile, except, as already stated, in the 

 river valleys. In the southern portions of Xew South "Wales 

 these are very numerous. 



It has been noticed that the actual amount of the rainfall on 

 the interior slopes must be largely in excess of the drainage by 

 the rivers, and that therefore a great portion soaks into the 

 ground and drains along the incline towards the interior. On 

 this account the structure of the central basin must be especially 

 favourable for the formation of artesian wells. This was drawn 

 attention to by me in a paper read for me by Sir Eoderick 

 Murchison, at the meeting of the British Association at Newcastle- 

 upon-Tyne, in 1863. In 1866, in a series of papers furnished to 

 the Australasian, I have advocated the same view. But it did 

 not receive much attention until recently, when the subject has 

 been revived with most beneficial results to the settlers of the 

 interior. One fact in the physical structure of the continent 

 should have indicated such stores of water in the interior. In 

 the central depression of the Continent there is a line of groups 

 of thermal and cold springs covering several hundred square 

 miles. These send forth water from great depths, and are, no 

 doubt, derived from a central underground reservoir whose sources 



