40 



Tlie relation and position AvLicli the younger South Australian 

 rocks occupy u^^on the upturned edges of the old pre-Silurian 

 beds are against the supposition of any very decided change of 

 sea level since the deposition of the former. It will be recog- 

 nised that no decided movement, either by way of depression or 

 elevation, can have taken place throughout the area of the Mount 

 Lofty pre-Silurian rocks since the deposition of the Torke's 

 Peninsula lower Silurian beds. These rocks, as exhibited there, 

 are resting almost in a horizontal position upon the upturned 

 €dges of the pre-Silurian beds. The seemingly massive charac- 

 ter of the beds and the manner of vertical fracturing, indicate 

 to my mind at least that no general movements have occurred, 

 either elevative or depressive, throughout the locality since 

 their deposition. The same considerations are applicable as 

 regards the horizontal condition in which the Miocene beds of 

 South Australia are invariab]}^ found resting. Therefore, 

 judging by the undisturbed condition of both the earlier and 

 the later formations, leads me to infer that no upheaval has 

 taken place in the neighbourhood of Adelaide sufficiently im- 

 portant to produce general glaciation of the surrounding 

 country since before the deposition of the lower Silurian beds 

 of Yorke's Peninsula. 



According to Dr. A. Geikie, the line of perpetual snow in the 

 Himalaya mountains is 19,000 feet above sea level. These moun- 

 beiug situated in latitude 22 degs. north, in round numbers, 

 let us say Adelaide is situated in latitude 35 degs. south, by the 

 same ratio Adelaide would require to be raised to the elevation 

 of 12,000 feet above sea level in order to bring it within the 

 influence of the permanent frost-line. Presuming Mount 

 Lofty to have stood at about the same height above the Ade- 

 laide plain at which it now stands, in that case the mount 

 would require to have stood at an elevation of nearly 11,000 

 feet above the plain to have brought it within the influence of 

 perpetual frost, which height would barely meet the require- 

 ments of the theory propounded by Eev. J. E. T. Woods ; and 

 much less would it have maintained glaciers at the present 

 coast-line. An elevation of quite 2,000 feet more would be 

 required to have brought these parts within the influence of 

 perpetual frost ; for, as already stated. Professor Tate and 

 others have detected signs of former glacial action in the 

 vicinity of our present coast-line. Besides, had any portion 

 of Australia been elevated to the extent of 12,29-1 feet about 

 150,000 years ago it coald not have been of local application ; 

 it must have extended pretty generally over the entire southern 

 portions of the continent of Australia. Had it been otherwise 

 the drainage of the present river systems would have been com- 

 pletely altered by such movements, but which, from evidence 



