BY R. M. JOHNSTON, F.L.S. 101 
ment Geologist, which has been read to us this evening, I 
had the privilege of reading beforehand. It contains a very 
interesting account of his recent geological observations, many 
of which are new and extremely interesting ; but, above all, 
it not only greatly extends our knowledge of glacial phenomena 
in Tasmania, but we have also a valuable examination of all 
collateral evidences, which bear directly or indirectly on the 
possible extent of glaciation in Tasmania generally during the 
glacial epoch, its intensity, and its cause; and upon the 
whole Iam gratified to find that his extended and independent 
inquiries lead him to a conclusion similar to my own, Viz., 
that although refrigeration of our climate was sufficiently 
intense during the glacial epoch to produce streams of glaciers 
upon our alpine regions in the west, and possibly in other 
mountains further south, he is inclined to believe that the 
refrigeration was not so intense as to cause the ice to invade 
the levels of our lowlands. He seems disposed, however, to 
expect the initiation of snowfields and glaciers in isolated 
mountains further east, but I have given my reasons already 
why I incline to think that the smaller amount of precipita- 
tion, and possibly the milder local climate of the eastern part, 
may have combined to turn the balance of summer melting 
against winter precipitation, and so cause a pluvial epoch, at 
most, in Hastern Tasmania. This inference, in my opinion, 
would harmonise more closely with all the known facts, and 
particularly with the total absence of any clear signs of glacial 
phenomena among our pluvial terrace drifts in the lower 
levels of Hastern Tasmania. 
_ Mr. Montgomery is also inclined to ascribe a greater de- 
nuding power to glaciers in the formation and deepening of 
mountain valleys and ravines than Iam myself disposed to 
allow. I admit they are very important agents in iutensify- 
ing the great work of denudation in mountain valleys, whose 
channels have already been deeply cut by flowing water; but, on 
the whole, the real carver of valleys and ravines, and the great 
waster of land surfaces is great precipitation, the more mobile 
gravitation, and the infinitely greater dissolving power of 
water in motion. Valleys originally formed by water agency 
determine the course which glaciers have followed, rather than 
that glaciers have determined and cut out the channels 
of valleys in which they have been known to occur. 
I am also of opinion that the greater denudation of the 
western slopes of the great greenstone plateau—which, in 
my work, “The Geology of Tasmania,” I inferred that it 
extended, probably at the close of the Mesozoic age, west- 
wards as far as the West Coast Range, which it partly 
embraced—was effected, and the leading features carved 
out, much as they are now found, long prior to our glacier 
