DISCUSSION ON NOTES ON THE MOUNT LYELL DISTRICT. 35 



Each of these subjects was quite large enough to require a 

 separate paper for its elucidation. Taking the new theory 

 of mountain elevation first, the writer referred to Mr. John- 

 ston's supposition that many of the Tasmanian mountains 

 are due to the shrinkage of the earth's crust, and dismissed 

 the whole contraction theory with the cursory remark that 

 " it has long since been proved " that that explanation was 

 insufficient. He thought that many other geologists would 

 agree with him (Mr. Montgomery) in denying that any such 

 thing had long since been proved. While it might be con- 

 ceded that other agencies were at work, he did not think either 

 that many would agree that the mere presence of the ocean was 

 the greatest. The subject of the rate of the cooling of the 

 earth and the contraction consequent thereon was a most 

 abstruse one, and there had been great difference of opinion 

 expressed about it. In his mention of the higher mountain 

 ranges, the writer left out of account the great range of 

 mountains extending from the west of Europe to the east of 

 Asia, and right away from any large body of water. The 

 theory enunciated was that the mere weight of huge bodies of 

 water pressing on the crust of the earth forced up a part of the 

 solid crust to a higher level, and he failed to see how such a 

 thing could happen. Water could only raise water to its own 

 level, and could not raise a heavier substance to a higher 

 level. The theory brought forward to account for Mounts 

 Lyell and Owen was a curious one, and he could not see the 

 probability of it, unless indeed the change was ascribed to 

 some grabbing influence from outside the earth altogether, 

 that being the only sort of force that could rake up the 

 material from the valleys and give the country a " dragged 

 out appearance." This and the further reference to the effect 

 of " the great weight of these accumulations " which are no 

 sooner raised up than they begin to settle down again, pre- 

 sumably directly against the force that has just raised them, 

 led one to think that the writer must have based his theory 

 on the supposition that the whole crust of the earth was a jelly, 

 and he suggested that this theory might be known as the Jelly 

 Theory, to contrast it with those generally accepted. The 

 "homely illustration" of the pamphlet was not a good one, 

 as the forces there applied were two lateral ones in opposite 

 directions, while that to be illustrated by it was one force 

 acting vertically. The writer stated that the " fissure theory, 

 which has been applied to the majority of lodes, is fast dying 

 out;" but his impression was that 999 out of every 1000 

 geologists or men connected with mining would hold that 

 theory as one that met the greater number of cases, and assert 

 that true lodes were almost universally found to be fissure 

 deposits. It was a fact that such packed spaces as alluded to 

 by the writer as being sure to occur if lodes had once been 



