96 RANDELL'S VOYAGE UP THE DARLING AND BARWAN. [April 23, 1860. 



500 feet in height, so unbroken that it was only here and there that Mr. Eyre 

 was able to scramble down some of the minor gullies, in order to supply himself 

 with the water that oozed out just at the base. There was not a single river 

 course nor a single valley which could give a channel to a river course between 

 the palaeozoic rocks of South Australia and the palaeozoic rocks of Western 

 Australia. Mr. Eyre described the geological formation of this great expanse 

 always in the same terms, which proved that they were horizontal beds of 

 tertiary rocks. He described them sometimes as chalk, and sometimes as 

 oolite, with flints, and containing oyster and other shells. There was flat land 

 on each side of the ridges of South Australia, likewise composed of horizontal 

 tertiary rocks, as was the case also round Port Phillip. There was another 

 expanse of flat land to the north of Western Australia running for hundreds of 

 miles between North- West Cape and the hilly ground of Cumberland Inlet. 

 The only information we had about it was derived from the marine surveys. 

 No large river came out there ; the coast was very low, fronted by sand-hills ; 

 and the view of the interior showed a great plain covered by salsolaceous plants. 

 Coming next to the Gulf of Carpentaria, all the accounts agreed in showing that 

 the land was very flat all round the head of the gulf. No fossils were ever 

 found there, therefore it could not be said positively that these plains were 

 tertiary ; but this was known, that no large river came out anywhere round the 

 Gulf of Carpentaria. Large river mouths were passed ; but Leichhardt always 

 said they were full of salt-water. There were certain rocks making the flat 

 land about Port Essington, resembling lithologically the rocks on the opposite 

 side of the continent, those round Port Phillip especially. Putting all these 

 facts together — that wherever you found these flat lands, and could identify 

 the rocks underneath them, you found horizontal tertiary rocks, and connecting 

 these great flat plains, which we knew existed on these three parts of the coast, 

 with the great plains of similar rock that Sturt passed over when he penetrated 

 into the interior, and that in the plains about the junction of the Darling and 

 the Murray you got similar tertiary rocks — it did seem to him in the highest 

 degree probable that all the interior of Australia was a continuation of the same 

 flat plain, made of the same horizontal tertiary rocks. These tertiary rocks 

 were all more or less porous. The beds of limestone were tolerably thin, and 

 interstratified with beds of sand, so that water would readily sink through 

 them. 



Next, as to the water that fell upon this ground. No doubt in certain 

 seasons — he did not mean in certain parts of the year, but in certain groups of 

 years — there were large falls of water over a great part of the country. Ac- 

 cordingly, after two or three wet years all the low lands would be saturated 

 with water, either on the surface or beneath it. Lakes would then be filled 

 with water, broad lagoons would be formed, and actual streams, occasionally, 

 when great floods ran off the land. But this did not give any permanent 

 supply of water or permanent navigable rivers. The water rushed off as a 

 flood, formed a river for a time, and the remainder then sank below the surface. 

 When once it sank to a considerable depth, where it was protected from subse- 

 quent evaporation, there would be a supply, which might be reached by digging 

 wells ; but it would be below the surface, not upon it. That the general cha- 

 racter of the climate of the country showed this alternation of wet and dry 

 periods he thought might be proved by going a little back into history. Tracts 

 of country which were once covered with water were now dried up and con- 

 verted into farms, and what were described as inland seas had disappeared when 

 the country was visited by subsequent explorers. An instance of the uncertain 

 nature of the rivers occurred to himself at Swan Eiver, since in riding up the 

 upper part of the Swan he had at one part a long reach of water on his left 

 hand, and a few miles farther on he found a reach of water on his right hand, 

 without having had to cross any water. He at first thought it was a second 

 stream ; but he remembered that he had a little way back ridden across a 



