42 



no doubt but that it has continued up to a very recent jjeriod, 

 if it be not now going on. The extent of this movement 

 also proves its slow and steady character ; and that it has 

 not been j^roduced by a sudden alteration in the relations of 

 sea and land is fully established by the sections exposed at 

 Table Cape, on the islands in Bass' Straits, and in the various 

 sections lying between Cape Leuwin and Cape Howe. If we 

 turn to New Zealand we have there evidence of the movement 

 in a direction southward and eastward ; and we may be sure 

 it is far within the mark when it is stated that the upward 

 tendency of the floor of the ocean in the southern portion of 

 Australia must have affected not less than 3,900,000 square 

 miles of the earth's surface. This is quite contrary to the 

 popular notion which represents Australia as a vast, aged 

 continent, which, in its inert senility, is slowly disappearing 

 below the waters of Oceania. No doubt the exposure of 

 such a large extent of palaeozoic rocks in Australia, together 

 with the great number of salt lakes and salt pans in the ter- 

 tiary districts, may have given some color of foundation to 

 this wide-spread impression. 



The vertical movement of the earth's crust is often con- 

 fused with other influences which help in determining the 

 boundaries of laud and sea. For example : the continuous 

 action of rivers hollow out channels, and cause extensive 

 deltas to be formed, which may conceal, to a great extent, 

 the actual vertical movement. The natural waste around 

 our coasts permitting a horizontal advance of the sea may 

 -often be mistaken for a sinking of the land ; and the gradual 

 wearing away of some rocky headland, or the effect of the 

 prevailing winds, may produce such extensive modifications, 

 in the shape of sand dunes on land and sandbanks in the sea, 

 as to make it very confusing to those who are not skilled in 

 tracing cause and effect in geology. Even to the latter the 

 signs are not always so apparent that they can at once be 

 recognised. It requires a patient exp.mination of particular 

 districts, and a careful collation of what, often at first sight, 

 may seem conflicting evidences. 



These observations are sufficient to exj^lain the local en- 

 croachment of the sea on our North- West Coast (as reported 

 to this Society many years ago by Mr. Gunn), and to show 

 that a local encroachment of the sea may be in perfect har- 

 mony with a slow vertical movement of the land upward. 



The following islands were recently visited by me : — 

 Waterhouse, Swan, Barren, Long, Flinders, Grreen, Kangaroo, 

 and Badger. The various islands are under lease to different 

 persons. Barren and Badger are now the homes of the half- 

 castes. The original home of the aboriginals, " The Settle- 



