126 THE GLACIER EPOCH OF AUSTRALASIA, 
the earth’s orbit with winter in aphelion occurring, according 
to Dr. Croll, 550,000 years prior to the glacial epoch of the 
Northern Hemisphere). ”. [then conclude with the observation 
(p. 256):—“The author is personally familiar with the 
various evidences of glaciation in Scotland at the higher and 
lower levels,and his knowledge of Tasmania is sufficiently 
wide to enable him to state with confidence that corresponding 
evidences in the latter place (t.e., obviously the lower levels) 
are entirely wanting within the tertiary and later periods.” 
In the recent paper already referred to, prepared by 
Messrs. Officer and Balfour, of Victoria, the authors erro- 
neously convert my statement as to the absence of evidence 
of intense glaciation into an assertion “that there is no 
evidence there (Tasmania) to show that a glacial period has 
ever taken place.” I make no such statement. I was the first 
person not to observe, but to publish evidence clearly proving 
ice action in the alpine regions of our western highlands, 
but the absence in lower levels of any evidence of ice 
action confirms my opinion as to the absence of zwéense 
glacial action during our glacier and pluvial epochs. 
In this view, regarding the absence of evidence of glaciation 
on the lower levels of Tasmania, Iam gratified to have the 
support of our able Government Geologist, Mr. Montgomery, 
for in his paper just read (‘Glacial Action in Tasmania’’), 
in referring to this very question, he states: “ In the main I 
agree with his view,” that is, with the view which I had in- 
clined to take as expressed in page 256 “Geol. of Tasmania.” 
Mr. Montgomery’s most valuable contribution to our 
knowledge of ice action, together with similarly valuable 
papers of Messrs. Dunn and Moore, now enable us to fix the 
limits of the upper and lower indications of positive ice 
action on the shoulders and slopes of our western highlands 
with a close approximation to the truth, at least sufficiently 
so to give us a fairly good base for determining the isochional 
of the névé or snow line of our western highlands, during 
the two great glacier periods already referred to. But first it 
is necessary to consider how far denudation may have reduced 
the height of our mountain tops. If we even allow in such 
situations a rate of denudation of three times that.of the 
average rate, which is estimated to be nearly one foot in 
3,000 years (that gives one foot per 1,000 years), we can 
only allow a lowering of altitude by about 850 feet since the 
beginning of the Pliocene period, at which time it is probable 
the refrigeration, due to the maximum of eccentricity in the 
earth’s orbit 850,000 years ago, might probably have caused 
the earlier glaciation of our western alpine region, which, 
even now, has a very extended surface (Great Greenstone 
Plateau) with a mean altitude of 4,000 feet. This allowance 
for denudation would bring the mean altitude of the same 
