39 



line. In connection with this subject it might be well to con- 

 sider that during the peroid of extreme glaciation of the 

 southern hemisphere, the permanent frost-line would stand 

 from eight to nine degrees nearer our shores than it does at 

 present, which would facilitate the passage of icebergs north- 

 ward to a similar degree as the permanent frost-line extended 

 in that direction. At the same time the eccentricity of the 

 earth's orbit was at a high value, according to Dr. Croll's 

 theory, and cold greatly predominating in the southern hemi- 

 sphere, whilst the southern shore-line of South Australia we 

 may suppose as submerged to the extent of from 800 to 1,000 

 feet. Judging from the dimensions of icebergs, noted by navi- 

 gators in the Southern Ocean at present, the southern shore- 

 line of Australia would then just be about the depth at which 

 bergs of such dimensions might be expected to strand. The 

 watery parts of which they were composed would soon give 

 way to the action of the surrounding warmth, which would be 

 considerably above the freezing point ; consequently, the more 

 coherent materials of these stranded bergs would soon drop to 

 the bottom of the sea, and as the land rose the greater portion 

 of this transported debris would emerge with it, as a puzzle for 

 the future geologist to determine its origin. It is not at all 

 improbable but that some, at least, of the boulders transported 

 n this manner may have been striated by the action of ice on 

 lands far away, long ere they started on their journey to be 

 exposed afterwards on a distant Australian shore-line. 



In his geological work on South Australia the Kev. J. E. T. 

 .Woods, (since the date in question I believe the rev. gentleman 

 ^has altered his mind on the subject of Australian glaciation) — - 

 attributes the primary cause of the glacier action he had ob- 

 served in the Mount Lofty Eange to the great altitude of the 

 chain during the glacial epoch. If any extraordinary elevation 

 of the chain ever existed, it must have been long anterior to 

 the date of the glacial enoch to which the rev. gentleman re- 

 fers. The pre-Silurian rocks, constituting the Adelaide chain^ 

 since their deposition have been subjected to vast contortions 

 and denudations ; nevertheless, I can discover no evidence to 

 show that the chain ever attained a much greater altitude 

 above sea level than it now attains. It seems to me a much 

 more probable hypothesis that the axial elevation of the range 

 was first determined by some slight undulation of the beds, and 

 for ought we know might have arisen in the ancient sea-bed, 

 which by a succession of upheavals ultimately would become 

 dry land. Denudation then would begin to operate, and the 

 slowly-rising land soon afterwards would become furrowed into 

 inequalities, and as the slopes of the first undulations enlarged, 

 the primary sketch of a mountain chain, with rivers, gullies, 

 and gorges, would be developed. 



