Page:A sketch of the physical structure of Australia.djvu/64

52"where, in a thickness of 25 feet, are seen several beds of a light-coloured, compact, hard, earthy limestone, separated from each other by layers of fine loose sand. Both in the sand and in the limestone are many marine shells, especially ostrea and pecten. Casts of shells, apparently venus or lucina and turritellæ, are also frequent, and some spatangi, of exactly the same species as those near Port Phillip and those I have seen from the banks of the Murray. I was struck with the perfect state in which the oysters were found in these quarries at Adelaide, and had mentioned in my notes their little altered condition, before I remembered that the same fact was mentioned by Sturt and Mitchell on the rivers Murray and Glenelg."

We will now briefly follow Captain Sturt in his last desperate attempt to penetrate into the central portion of Australia. Going up the Darling from the Murray he speaks merely of plains which we have seen reason to believe are all composed of the tertiary formation until we approach the Barrier or Stanley range, which rises in lat. 32&deg;; there he speaks of the surface being covered with fragments of white quartz, which together with a conglomerate rock cropped out of the ground where it was more elevated (p. 151.)

In this range, the hills of which are in some cases nearly 2,000 feet high, he describes the occurrence of fine hepatic iron ore in great quantities, and speaks of soapstone, of gneiss, of granite, of coarse ferruginous sandstone, and a siliceous rock, p. 166. He afterwards mentions in this range trap, coarse grey granite, "immense blocks," and "huge masses" of granite, p. 175, &c. He then