Page:A sketch of the physical structure of Australia.djvu/56

44 the rocks is said to be N.N.E., dipping sometimes westerly, sometimes easterly at high angles. At Tarratta we again meet with granite, and in the plains beyond with porphyry, while near Regent's Lake, Sir T. Mitchell mentions trap and calcareous conglomerate like the tufa of caverns. We then come to Peel's Range on the south of the river Lachlan, which Mr. Oxley says is sandstone resting on granite, and to other hills on the north of the river, of which Mount Grarnard is one, among which Sir T. Mitchell mentions the occurrence of hornstone (granular feldspar)? trap and quartz rock. The most westerly hills of this range, which runs north and south, are however, all ferruginous sandstone, and from them the view is uninterrupted to the west, and extends over the apparently boundless plains which spread round the junction of the rivers Murray, Murrumbidgee, and Lachlan, and stretch thence to the banks of the Darling. We have now only to follow Captain Sturt and Sir T. Mitchell, in their course down the Macquarrie, the Bogan, and the Darling. On the former river Captain Sturt describes decomposed mica slate, feldspar and schorl rock as occurring at the falls a little north of 32&deg;, and basalt at Mount Harris and Mount Foster in about 33&deg;. On the Bogan, Sir T. Mitchell met with mica schist, and quartz, whinstone, granite and porphyry, near where Mr. Cunningham was killed about lat. 32&deg; 10′ and long.