207 
ice of no great thickness, and therefore incapable of transporting 
stones of large size. These suggestions are only thrown out as 
possible causes for the peculiar features of these beds rather than 
any settled conviction as to their origin. 
The geological age of this furmation is doubtful. It does not 
appear to have been subjected to the metamorphic action that 
has converted the sandstones of the Mount Lofty Ranges into 
quartzites. It is free from vein quartz, which is a genera! feature 
of the latter, as well as being more friable. The derived lime- 
stones in the Breccia-beds are crypto-crystalline, and resemble 
some of the Cambrian marbles, but no fossils have been detected 
in them. 
If the Breccia-beds are genuinely glacial in their origin, they 
are certainly much older than the glacial clays and erratics more 
particularly described in this paper, for the following reasons :— 
1. No erratics at all comparable in size to those scattered over 
the surface occur in the Breccia-beds. The size of the stones in 
the latter seldom exceeded a foot in diameter. 
2. Whilst some of the glacial erratics rested on the eroded 
edges of the sandstone and Breccias, there is no lithological 
similarity between the superficial erratics and the fragments 
which make up the Breccias. 
3. At several points the boulder clay is seen to rest uncon- 
formably on the eroded edges of the Point Marsden series. 
Judging from the general appearance of the sandstone, 
together with the occurrence of derived (?) Cambrian limestones 
in its Breccias, I am disposed to regard it as belonging to one of 
the middle or upper Palzeozoic periods. The shale beds that are 
included in the series might be carefully searched fur fossils with 
some hope of success. Great interest attaches to the westward 
extension of these beds, as their junction with the older rocks 
will probably be found in that direction, and might show an 
unconformability. 
