DISCUSSION OX NOTES ON THE MOUNT LYELL DISTRICT. 37 



1. " The presence of the ocean is the greatest of these." 



2. " We have not only the horizontal pressure of the ocean, 

 but also the vertical pressure, and the force varies with the 

 tides, this movement being more effective in shifting the 

 earth's crust than a direct pressure." 



3. " 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." 



The nearest approach to Mr. Power's suggestions which I 

 have been able to find, is that of some American geologists, 

 viz. : — " That the removal of rock by denudation from one 

 area, and its accumulation in another affects the equilibrium 

 of the earth's crust, and causes subsidence where deposition 

 takes place, while the denuded area being relieved of weight 

 rises ;" this, however, has been fully met by proof that 

 "should the removal and deposit of a few thousand feet of 

 rock so seriously affect the equilibrium of the crust as to 

 cause it to rise and sink in proportion, it would evince such 

 a mobility in the earth as could not fail to manifest itself in a 

 far more powerful way under the influence of lunar and solar 

 attraction." If, then, the pressure of a few thousand feet of 

 rock be incapable of raising the level of neighbouring dis- 

 tricts to any appreciable extent, still less can the pressure of 

 water, which has only about one-third the specific gravity of 

 rock, be capable of slowly raising land, and sending it rolling 

 inland " like immense fossil waves." If such were the case 

 still greater would be the mobility and the influence of lunar 

 and solar attraction. With regard to the Iron Blow I have 

 found some difficulty in following Mr. Power's theory ; but in 

 view of the close neighbourhood of the iron pyrites and the 

 hematite, of the fact that each is schistose in structure, that 

 each contains much barytes, and that the hematite is on the 

 footwall of the vein or deposit, I am still of the opinion 

 expressed some time back in reply to Mr. Thureau : that the 

 Iron Blow itself is the result of the decomposition of some of 

 this large deposit of iron pyrites. I will only allude to the 

 question of "fissure" veins to point out that Mr. Power 

 quotes no authority against and suggests no substitute for 

 "this fissure theory," as he terms it. In conclusion I can 

 only agree with Mr. Montgomery that Mr. Power, notwith- 

 standing his disclaimer, has drawn on his imagination for his 

 theories. . 



