148 A Physical Description 



east of New South Wales. The outline of the country around 

 Lakes Bathurst and St. George in that colony is very 

 similar to the lake districts of Tasmania. They are of good 

 elevation, and the geological structure of the rocks is the 

 same. 



But though the elevation of the island of Tasmania has 

 resulted in a certain extent of elevated plateaux, yet it has 

 produced in far the greater portion of its extent an uneven 

 surface, composed of broad or narrow mountain ridges or 

 isolated hills. There are three phenomena which are 

 visible here as elewhere: — 1. Elevation; 2. Intrusion, or 

 overflowing of volcanic rock ; 3. Denudation, or weathering. 

 All these causes may have been in operation until recently, 

 and the last is still going on. The results of endless change, 

 breaking up, and redistribution have produced such altera- 

 tion in the strata that it is next to impossible to assign 

 any particular appearance to its original cause. Thus 

 a mountain which is now a pinnacle may originally have 

 been a dome, and a sharp or jagged range may have been the 

 edge of a tableland. There are many and various chains of 

 mountains running through the island, some on the edges of 

 the plateaux, and some running actually through their midst. 

 Thus different directions have been traced by Count 

 Strzelecki and others. It must be borne in mind when 

 studying them that they are not certainly axes of elevation, 

 and do not correspond in every respect with the general 

 configuration of the coast line. 



Beginning at the north-east extremity of the island — Cape 

 Portland — we find a small ridge about 700 feet high. At a 

 point called the Black Ridge the commencement of the 

 great area of elevation is reached, and the land suddenly rises 

 to above 3000 feet. The chain then takes a south-west direc- 

 tion, and sends off three long branching spurs. The first is 

 the source of the River Boobiala, and terminates in a 

 cluster of conspicuous granite hills, of which the most 

 prominent is Mount Cameron. Next to that is the green- 

 stone of Mount Horror, Mount Barrow, Mount Arthur, and 

 Mount Direction. This spur continues as far as the mouth of 

 the Tamar and ends with Mount Royal. The last spur is the 

 highest part of the mountain system of this side of 

 Tasmania, including the lofty summit Ben Lomond. " It 

 is impossible," says Count Strzelecki,* " to give an adequate 



* Physical Features of N, S. Wales, <$'c, p. 66. 



