GEOGRAPHICAL UNITY OF EASTERN AUSTRALIA. 421 



I. Introduction. 

 Definition of title.— By the term geographical unity 

 as employed in the present paper, the writer wishes to 

 convey the idea that during the Pliocene, Pleistocene 

 and Historic Periods, the whole eastern side of the con- 

 tinent moved in the main as a unit, thus giving rise to 

 tectonic and erosional forms practically identical, when 

 considered in strips parallel to the coastline from Thursday 

 Island to the Murray River in Western Victoria. The 

 inference from this is not that each strip has arisen or 

 subsided exactly in the same degree, but rather that the 

 movement of the eastern continent, as a whole, has been 

 similar during each successive period. For example, it is 

 not here considered that the Miocene shoreline corres- 

 ponded with the present one. On the other hand the idea 

 is here advanced that Eastern Australia was a peneplain 

 raised but little above sea level toward the close of the 

 Miocene, and that its shore line doubtless lay considerably 

 to the eastward. The present shore line is here considered 

 as belonging to the Human Period, while the plateaus and 

 the main outlines of the continental shelf are considered 

 as being due to agencies which closed the Tertiary Period- 

 Again, the peneplain of Eastern Australia was so warped 

 and faulted at the close of the Pliocene, or the commence, 

 ment of the Pleistocene, as to be carried upwards to 

 heights varying from 1,500 to 7,300 feet above sea level, 

 with the production of great block faulting in its south, 

 eastern knot ; nevertheless upon a broad view the High- 

 lands appear to be a flat arch, somewhat like a boomerang 

 in plan (Fig. 1), the long curve of which parallels the 

 coastline. Considered as a whole the plateau surfaces 

 slope away east and west from a sub-horizontal surface f 

 yet the local plateau surfaces may slop.- to the north-west, 

 as at the heads of the Barwon, to the north-east 1 as to the 



