40 NOTES ON THE MOUNT LYELL DISTEICT, TASMANIA. 



existing land was depressed to the same amount very exten- 

 sive areas of what is now dry land would be overflowed by 

 the sea; that the movements of elevation which have 

 occurred from time to time in various parts of the land areas 

 of the globe have been the result of forces acting in different 

 directions — vertical and horizontal ; that extensive platforms 

 have been raised by the former, while the latter will throw it 

 into plications of which the elevated portions will form 

 mountain ranges. "Also, the largest mountain chains 

 characterise the borders of the greatest oceans, showing that 

 the lateral pressure from the direction of the oceans was ap- 

 proximately proportional to the extent of the oceanic basin." 



Now, the reason I chose to illustrate my views by South 

 American and Tasmanian mountains in preference to the 

 Urals, as Mr. Montgomery would like, was because I pre- 

 ferred to write of places I have visited, and not depend on 

 maps more than necessary. And here I would remark that 

 during my several trips to Tasmania, which have extended 

 north, south, east and west, I have been careful to note the 

 general direction of the main ranges, often climbing to lofty 

 summits in order to attain my ends. However, if Mr. Mont- 

 gomery prefers to discuss the Urals I am willing, and would 

 direct his attention to the immense tract of low-lying 

 swampy ground forming the Siberian plain to the east of the 

 Urals, and north of the Altai, Yablonoi, and Stannovoi 

 Mountains ; also to the inland seas (Caspian Sea and Sea of 

 Aral) and the numerous lakes forming a chain all the way 

 north to the Gulf of Obe. Does not all this remind us that 

 this land has at some time been submerged by the ocean, and 

 would not require much change in its level to be flooded 

 again ? We thus see that though the Ural mountains are 

 now away inland, they were once a coastal range, as were the 

 easterly and westerly mountains above mentioned, which also 

 run parallel to their former sea coast. 



Tides and currents also have their effect on moun- 

 tain building, not only on account of the sedimentation 

 which they assist, but also by their own mechanical force. 

 Thus* we find the currents of the Bay of Biscay strongest 

 opposite the Pyrenees ; where the currents impinge on the 

 Calif ornian coast we find the Sierra Nevada ; large currents 

 curl round on the Chilian coast, and there we have the 

 Andes ; while coming nearer home we have the main current 

 sweeping along the east coast of Victoria, close to our 

 Australian Alps. The enormous weight of water in our 

 oceans — 36 times the volume of land — also tends to press 

 out any inequalities that form on its bottom, and drive them 

 onward towards dry land, where they are relieved of their 

 pressure. To take another homely illustration, as if one were 

 to flatten out a portion of a sheet of paper which 



