26 NOTES ON THE MOUNT LYELL DISTRICT, TASMANIA. 



east coast, the Pacific again being larger than the Indian 

 Ocean. In Tasmania, however, matters are somewhat 

 different, for there is an unbroken stretch of water from its 

 west coast to South America ; while on its east coast, some 

 twenty degrees distant, New Zealand acts as a breakwater, 

 and braces up the ocean, so to speak, relieving the east coast 

 of Tasmania of much pressure from the main body of water. 

 Therefore we are not surprised to find that the backbone of 

 Tasmania is on the western side, especially when we find a 

 map in Wallace's " Island Life " showing the deep water on 

 the west coast at 2,600 fathoms, against 2,000 fathoms on 

 the east coast. We not only have the horizontal pressure of 

 the ocean, but also the vertical pressure, and the force is not 

 a steady one, but varies with the tides, this movement being 

 more effective in shifting the earth's crust than a dead 

 pressure. The pressure of the immense bodies of water in 

 the oceans are working as bard to-day in the building up, 

 and indirectly in the pulling down, of our mountain systems 

 as they have in the past, and it makes its pressure felt second- 

 hand by the enormous weight of the rocks that they pile up, 

 which in their turn exert a vertical pressure. We generally 

 find that the actual coastal range is not so high as the next 

 inland one, as if the force causing the mountain system had 

 limited the area on which the range nearest to it could draw ; 

 also that the ranges following the main one are lower and 

 further away from each other as they go inland. So in the 

 case of Tasmania we find the West Coast Eange compara- 

 tively low. Then comes the Main Range, including the 

 Frenchman's Cap, Eldon Eange, and the Cradles, which are 

 among the highest mountains of Tasmania, These are 

 followed up further inland by the King William Eange. 

 These ranges are like immense fossil waves rolling inland. 

 They have a long slope on their western side and a steep one 

 on their eastern, just as if they had been pushed up by the 

 sea. Having taken a flying survey of the physical features of 

 Tasmania we will now make a few remarks relative to the 

 mineral wealth of the West Coast, and more particularly to 

 the Mount Lyell district. 



GrEOLOGY. 



The West Coast of Tasmania is rich in the variety of its 

 minerals, among which ores of the following metals are 

 found: — Tin, gold, silver, lead, zinc, copper, iron, chromium, 

 nickel, bismuth, wolfram, iridium, antimony, manganese, and 

 mercury ; also other minerals of commercial value — e.g., 

 marble, serpentine, asbestos, lignite, etc. 



Mount Lyell (named after the celebrated geologist, Sir 

 Charles Lyell) — and its district is a most interesting one from 

 a geologist's point of view, for here we [have two or three 



