Crawrorp.—On the Probabilty of finding Extensive Coal Deposits. 888 
The above quotation fully disposes of the question of the formation of 
coal from an increase of vegetation caused by a supposed greater internal 
heat at the time of deposition, on the theory of secular cooking of the 
earth, 
I should not have entered upon the question at all, had I not found, in 
the course of conversation, that many persons were fully persuaded of, and 
held as an article of faith, the idea of the growth of the coal plants from 
the effect of internal heat. 
I hope that I have succeeded in showing the fallacy of that view, and 
that we must fall back upon the rays of the sun as the true producers of 
the coal vegetation. The existence of animal life in the palwozoic ocean 
proves that changes in the temperature of the ocean since that time, if any, 
must have been confined within narrow limits. 
Art. LY.—On the Cause of the former great Extension of the Glaciers in 
New Zealand. By Captain F. W. Hutton, F.G.S. 
[Read before the Otago Institute, May 11, 1875.] 
Tue former great extension of our glaciers is too interesting a topic to have 
escaped discussion, and, consequently, we find that it has formed the sub- 
ject of several papers read to the various scientific societies in New Zealand, 
in addition to the notices that occur in some of the reports of geological ex- 
plorations in the South Island. Nearly all the authors of these papers are 
now agreed that the extension of the glaciers was owing to the elevation of 
the land ; but this opinion, which I believe to be correct, has been arrived 
at in a very loose manner, and at the present time even it is not entitled to 
greater weight than that of a shrewd guess. In a former paper on the 
subject* I advanced a few arguments in favour of it; but I now know that 
these arguments are fallacious, as many of the shells there taken as sub- 
tropical forms range to the southernmost part of New Zealand. 
Not liking to leave the question in this unsatisfactory state, I have lately 
turned my attention to it again, and think that I am in possession of suffi- 
cient information to put the subject on a tolerably sure foundation, and I 
wish, therefore, now to place my reasoning before you, in order that it may 
be discussed and corrected, if necessary. 
In order to arrive at any definite conclusion, it is, in the first place, 
necessary to ascertain approximately the present height of the snow line in 
New Zealand. This is not an easy thing to do, for although the theoretical 
* “Trans N.Z. Inst.,” Vol. V., page 384, 
