284- Transactions.— Geology. d 
Авт. XLVIL— On the Formation of Mountains ; a Reply to the Rev. 
О. Fisher. By Capt. F. W. Ноттох, F.G.S, 
[Read before the Wellington Philosophical Society, lat September, 1873.] 
Havina, at the last meeting, been requested by the President to lay before the 
Society my reply to the Rev. O. Fisher's critique, which appeared in the June 
number of the Geological Magazine, on my previous lecture on the formation 
of mountains,* I have now the honour to do go. 
I have, in the first place, to thank Mr. Fisher for recaleulating— more 
correctly, no doubt, than I have done—my table of the altitude of domes, and 
also for explaining several points which I had not clearly conceived before. 
Nevertheless, I think that I shall be able to show that his arguments against 
the theory that I have advocated are not well founded. 
For the sake of conciseness I will, in what follows, call the theory that 
Mr. Fisher advocates the “contraction theory,” meaning thereby the theory 
of the formation of mountains by the secular cooling and contraction of the 
earth ; while I will call the theory аё I advocate the “ deposition theory,” 
by which I mean the theory of the formation of mountains by the removal of 
matter from one portion of the earth and its deposition on another portion. 
In my lecture I called this latter the “ Herschel-Babbage” theory, but I have 
since ascertained that Mr. Scrope was the first to suggest it, and it has there- 
fore no right to the name that I applied to it. 
(a.) The first argument that Mr. Fisher adduces against the deposition 
theory is, that any lateral pressure of expansion must be taken as strictly 
- horizontal, and could not cause an upward rising. But the pressure relied on 
by Mr. Fisher to produce mountains is just as horizontal as the pressure 
produced by expansion, and if a cube foot of rock would be simply compressed 
by the horizontal pressure caused by expansion, why should not the effect 
be the same if the horizontal pressure was produced by the contraction of the 
nucleus? Practically we know that a perfectly horizontal sheet of dry paper 
stretched on a board will wrinkle when its dimensions are increased by 
damping; and the crust of the earth must do the same unless it crushes, 
From observation we know that anticlinal curves have been formed, and that 
the crust therefore does not always crush up. 
Mr, Fisher also says that “we have no right to consider the crust rigid 
when regarded in proportions of sufficient dimensions to admit of these lateral ` 
pressures being otherwise than sensibly in the same Straight line, but in 
opposite directions.” In "his first paper, however, on the formation of moun- 
tains (Trans, Camb. Phil. Soc., 1869), he not only says that the portion of the 
* See Trans, N.Z. Inst, Vol, V., App., p. xxv. 
