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18 a semi-bituminous deposit which has been taken for coal. Tin and zinc have also been reported as existing in several places, but have not yet been discovered in workable quantities. Mr. Brown attributes the argillaceous clays, shales, and schists to the Silurian period, the bituminous shales to the Carboniferous, the sandstones and limestones to the Oolitic, but the coast limestone, evidently a more recent concretion, must be excepted, which, with its accompanying beds of calcareous grit and sandstone, he attributes to the Tertiary period. Some of the fossils which these limestones contain, differ but little from species still existing on the shores of the Colony; but Mr. Brown seems to think that the clays and laminated rocks found at the base of the hills may underlie them.

This outline sketch of the Geology of Western Australia may be sufficient to account for its most apparent physical features, but some further Geological notices will be required in considering them more in detail. On examination, the coast line of Western Australia will be seen to present three deep indentations—at King George's Sound on the South, Shark's Bay on the West, and King's Sound on the North coast, all trending to the Westward of North. To the West of King's Sound there is an extensive bight, reaching nearly to the N.W. angle of the Colony, while, on the South coast, the Great Australian Bight stretches Eastward from Cape Arid; and lines drawn from Fowler's Bay (beyond the Eastern limit of the Colony) to King's Sound, and, parallel to it, Northward from Cape Arid and Southward from Shark's Bay, will divide the Colony into three districts, trending about N.N.W. and S.S.E.


 * 1. The Desert district, continuous beyond the Eastern limit of the Colony.