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north,—to that of the Great Australian Bight on the south, and to stretch along the N.W. coast, from Northwest Cape to Collier Bay.
As minor, but sufficiently important features, may be mentioned,—
4. The mountain chain of South Australia running north from Cape Jervis to the singular horse-shoe shaped depression of Lake Torrens.
5. The high land of Western Australia, running north from Point D'Entrécasteaux and King George's Sound to the neighbourhood of Shark Bay.
6. The high land which forms the coast from Collier's Bay to Wickham's Victoria River, and seems to stretch in an east and west direction across the interior of Arnhem Land, south of Port Essington to the western shores of the Gulf of Carpentaria.
I shall endeavour to describe the structure of each of the districts above named somewhat in the above order.
I.—The Eastern Coast.
The mountain chain of the eastern coast is, apparently, a rather irregularly formed and complex one, but, it seems to preserve the same or very similar features throughout its extent. It is no where, so far as is known, a single ridge of mountain, but is made up of many masses of various
