Page:A sketch of the physical structure of Australia.djvu/42

30 with granite to the eastward of the river which forms the division between them (p. 244), after which scarcely any other rock but granite is mentioned till they began to descend the river Lynd, north of the Kirchner range in lat 17&deg; 20', north of that point nothing but sandstone is mentioned or psammite (large grains of quartz mixed with whitish red or yellow clay), till they got down to the sandy plains of the Gulf of Carpentaria.

The only points of the coast of the main land which I visited north of Cape Melville were Cape Direction, which was composed of granite fronted by sand, and Cape Grenville, where the only rock seen was a brown quartz rock with dark compact feldspar. The islands near the latter Cape, were either sand banks on coral reefs or rocky islets, like Sunday Island, and Sir C. Hardy's Islands, which were composed either of compact feldspar, of quartz rock, or of brown feldspathic and siliceous slates and schists. Around Cape York as well as in all the adjacent islands, Mount Adolphus, the Possession Islands, Prince of Wales's Islands, and Booby Island, no other rock was seen than a heavy compact dark coloured porphyry or greenstone.

E.—Torres Straits.

North of Cape York a narrowing chain of high rocky islands stretches right across Torres Straits up to the coast of New Guinea. Of these I believe Mount Augustus and Mount Ernest to be granite though I did not land on them, Saddle Island was