66 



mostly destitute of stratification, and generally contain erratics. 

 Even where no stones can be seen in the face, striated stones are 

 almost invariably found on the surface of outcrop as though 

 weathered out from the bed. 



The borings put down by the Port Victor Coal Prospecting 

 Company in the Back Valley show throughout their entire depth 

 alternating dark arenaceous mudstones with sandstones and 

 boulder beds similar to those observed at the surface. The con- 

 tinuity of the glacial beds to the 960 ft. depth, as proved by 

 bores, seems beyond doubt. This gives a thickness approxi- 

 mately of 1,500 ft. of glacial deposits in the Back Valley. 



[The association of Till beds intercalated with yellow sand- 

 stones, as described above, offers a close analogy with the Bacchus 

 Marsh series of Victoria.] 



2. The very wide area over which glacial features have now 

 been proved to exist leads to the conclusion that the greater part 

 of the Cape Jervis Peninsula, with Port Victor and Normanville 

 (or even Myponga) as the base of the triangle, has been visited 

 by ice, an area of more than 300 square miles. 



3. The direction of the striae, as well as the distribution of the 

 transported material, point to the region of the Southern coast, 

 from Port Elliot to Kangaroo Island, or even much further into 

 the Southern Ocean, as the probable centre of dispersion. Blocks 

 of Port Victor granite can be traced as far North as Hallett's 

 Cove. The direction in which the ice travelled was therefore in 

 opposition to the present drainage of the land, which is, generally 

 speaking, from North to South. 



4. In the present stage of our observations it is a little difficult 

 to say definitely what form the ice took in this extensive glacia- 

 tion. Was it in the form of glaciers, icebergs, or coast ice 1 

 Many of the phenomena seem best explained by the supposition 

 of land ice as the agent — such as the great extent of polished 

 rock surfaces [as at Hallett's Cove], the depth and uniform 

 direction of the striae, and the great number of scratched and 

 facetted stones contained in the drift. If the ice was in the 

 form of glaciers, it would require a great extent of highlands to 

 the South, sufficient to form vast snowfields, from which tongues 

 of ice radiated. The transported material being essentially local 

 in its origin, is not likely to have been carried by icebergs, so 

 that the only alternative is that of ice-floes or coast-ice being the 

 transporting agent. On this theory the Bald Hills, which are 

 now 600 or 700 feet above sea level, and are capped with glacial 

 drift, must at the time of glaciation have been at or below sea 

 level. When the locality has been more thoroughly examined, 

 it is not unlikely that evidences will be found that will set this 

 question at rest. 



