Page:A sketch of the physical structure of Australia.djvu/47

35 from some old very violent eruption of the volcanoes of New Zealand, or of one or more of the foci of the volcanic band between that country and New Guinea. Their occurrence above high water mark does not necessarily involve the supposition of the elevation of the coast, as a wave of sufficient magnitude to float them into their present position may have been the result of one or more earthquakes which probably accompanied the exhibition of the volcanic violence by which they were originally produced.

In the southern part of New South Wales, indeed, and in Tasmania there are evidences of elevation of the land, not only in the tertiary rocks, now high above water, but in raised beaches and in beds and accumulations of sea shells beneath the present soil to very considerable altitudes; but all along the N.E. coast of Australia I looked in vain for any conclusive evidence of such a fact, and the existence of the Great Barrier reef off that coast would, if Mr. Darwin's theory of coral reefs be the true one, involve the supposition of great depression having taken place through a long period of geologically recent time. On this subject I have spoken more fully elsewhere.

We have now to leave the eastern coast and proceed in our examination of the country towards the west.

Let me first state that the coast on the south side