43 



As far as I have observed in Australia this occurs wlere upper 

 and lower Silurian rocks are intruded upon by veins of Diorite. 

 The whole of these regions, if we include the table land, have 

 a distinct vegetation, alpine in the southern portions, and in 

 the northern more Australian and less Asiatic than the vege- 

 tation of the coast regions in the same latitudes. The third 

 region is the interior or western slopes of the dividing ranges. 

 Here the land is generally level, and more or less of a desert 

 character. Where the tertiary or desert sandstone prevails,the 

 desert is absolute. Thesoilis loose sand, supporting either open 

 forest with coarse grass, or dense shrubs of some kinds of 

 Eucalyptus or Acacia. This region extends to the centre of 

 the continent and beyond. This is also the litoral region of 

 the south coast, where not mountainous. It is more Aus- 

 tralian in its vegetation than any other portion, and possesses 

 fewer strangers, that is, plants indigenous to other countries. 

 It has very recent tertiary rocks, notably the desert sand- 

 stone, but whether marine or fresh water has not been deter- 

 mined, though probably the latter. Palaeozoic rocks are not 

 unknown, but do not often appear, though granites crop out 

 continually. It appears that the two first regions are well 

 represented in Tasmania, with, of course, certain modifica- 

 tions, which modifications I am inclined to suggest tend to 

 show that the insularity of Tasmania is at least of some 

 duration. The litoral features of the east coast of Australia 

 are very strongly marked in this Island. !Not, however, 

 confined to the east side of it, but continuing all round the 

 land which fringes the mountain ranges. The difference is, 

 however, also marked. The climate is much affected by the 

 gap of Bass Straits, and the vegetation is also less luxuriant, 

 and quite temperate in character, while its affinities are more 

 Polynesian and Neo-Zelandic, or Pacific than Asiatic. 

 Tertiary, marine, and fresh water rocks are sometimes met 

 with occasional litoral deposits. Tertiary volcanic deposits are 

 also common, but belonging all to the earlier series. The 

 light scoriaceous dolerites, trachytes, leucites, and olivines, 

 with ash tufas, which are never met at any great distance from 

 the sea in Australia, appear to be absent from Tasmania, as 

 they are from the East Coast of Australia. The second, or 

 table land region, is well represented in this Island, and with 

 great diversity of features. We have high mountainous 

 ranges, exposing precipitous rocks of various age, all however, 

 Palaeozic. The disturbance has exposed sandstone in flat- 

 topped hills, peaks, and downs of silurian age, with syenitic 

 granitic domes and peaks. The whole form of the mountains 

 appears to be mainly affected by dioritic intrusions of post 

 Devonian age or early tertiary dolerites. These show the island 



