80 



Island, we have probably reached the extreme southern limits of 

 our observations in the direction of their source. Beyond this 

 point the sea shrouds the rest in its eternal mysteries. 



General Geological Notes 

 Observations on the geology of Kangaroo Island have been 

 published by the French navigator and explorer, Peron ;* the 

 late Professor Ralph Tate,t Mr. H. Y. L. Brown |(Government 

 Geolof^ist), and the present writer.i^ Whilst the principal object 

 of my late visit to the Island had reference to the occurrence of 

 (^lacial evidences, a few general observations were made, and I 

 take the present opportunity of placing them on record. 



Arch^an or Paleozoic. 

 On the southern side of the Cygnet River the land rises to a 

 low ridge, which forms the geological axis and watershed of the 

 Island. This elevated land shows an exposure of older Palaeozoic 

 rocks, consisting of soft, easily decomposed flaggy quartzites, 

 somewhat rarely interbedded with clay slates. The beds have 

 an E.jST.E, and W.S.W. strike, the latter being very persistent in 

 direction, so far as ray observations extended on the Island. The 

 older rocks, which form the geological axis of the Mount Lofty 

 Ranges, gradually curve westerly as they approach Cape J ervis^ 

 whilst the strike slowly changes from approximately north and 

 south to a direction more nearly east and west. This occidenta- 

 tion of the strike is still further accentuated on Kangaroo 

 Island, the geology of which must be regarded in its main axis 

 as simply a continuation of the ranges which constitute the 

 physiographical backbone of South Australia. 



On both sides of this quartzose range, and on its lower slopes, 

 the subsoil is a yellowish clay, usually covered with a few inches 

 of loose sand and small ironstone gravel. 



The south side of the Island is included within the highly 

 metamorphic zone which is characteristic of the eastern side of 

 the Mount Lofty Ranges, the rocks of which follow a similar 

 westerly curve as the less altered beds already described. This 

 metamorphic belt takes in the bed rocks of the Murray Plains, 

 the coast line of Port Elliot, Port Victor, and the principal head- 

 lands on the south side of Kangaroo Island. It is to the existence 

 of these granite headlands that Kangaroo Island owes its preser- 

 vation from complete marine denudation. Unfortunately, great 

 thicknesses of recent deposits overlie these plutonic rocks along 



*Voyage de Decouvertes aux Terres Australes. 

 tTrans Roy. Soc, S.A., v. VI., p 116. 

 JReport, Dec. 13, 1898. 

 §Loc. cit. ante. 



