86 THE GLACIER EPOCH OF AUSTRALASIA. 
of the South Australian province by as much as 1,000 
feet, and of this submergence he rightly adds, “‘ That 
the known facts do not warrant such assumption.” But 
is there any necessity that the advocates of the hypothesis 
of “floating ice” as the agent of abrasion and transport 
should assume any depression whatever? On the contrary, it 
seems to me that an elevation of, say, 70 to 100 feet of the old 
sea-bed at the time of glaciation would answer all the condi- 
tions which the phenomena of glaciation and _ present 
elevation (40 feet above present sea level) demands; and this 
would allow a depth of from five to ten fathoms of sea over 
the channel along whose course the glacial phenomena have 
been traced. It would, in the latitude of St. Vincent 
Gulf (85° S. latitude), require an elevation of the whole 
land to a height of 12,000 to 14,000 feet, with a subsequent 
final depression of about from 11,600 to 13,600 feet to 
account reasonably for the present level of the glacial pheno- 
mena at Black Point, and for the present altitude of the higher 
members of the old tertiary marine beds; and this double 
assumption is of a far more serious character, and is far less 
warranted by known facts than the submergence of 1,000 
feet, for which, also, there is not the slightest necessity for 
assuming, unless it be also insisted upon that the very 
doubtful appearances of gkaciated surface on the heights of 
the Adelaide range are also to be explained as having been 
eaused by the same agency which produced the glacial 
phenomena. Notwithstanding my very high appreciation of 
the judgment of Professor Tate, better evidence than has yet 
been produced will be required before such a conclusion can 
be satisfactorily established. 
Until such evidence is produced, I shall be inclined to 
favour the hypothesis of “ partly stranded polar drift ice,” 
carrying debris in summer from neighbouring southern shores, 
not necessarily polar, where the ice drift may have been 
stranded for some time during the long severe winter. The 
period when such action took place is likely to have been at 
a time when the eccentricity of the earth’s orbit combined 
with winter in aphelion attained its greatest limit subsequent 
to the deposition of the rocks of miocene age. According to 
Dr. Croll’s published tables showing the varying amounts of 
eccentricity for three million years back, it would appear that 
the periods of high eccentricity have been exceedingly 
numerous in that time, and one or two of them far higher 
than that which is supposed to have been the principal cause 
of the great glacial epoch of Europe and North America in 
the pleistocene period. 
Now most of the Australian geologists incline to believe 
that the period of greatest glacial action in Australasia 
