172 Proceedings of the Royal Society of Victoria. 



cote, Pelluebla, Glenrowan, King Valley, Springhurst, Tarrawin- 

 gee and Wooragee, and in south central Victoria, as at Bacchus 

 Marsh, and under the deep leads at Pitfield, prove that they were 

 originally very extensive. The period to which they belong 

 being now generally recognised as Permo-Carboniferous or Car- 

 boniferous makes it highly probable that during the Jurassic 

 period much larger areas were covered by them than is now the 

 case. Consequently the derivation of these peculiar pebbles from 

 such deposits seems probable. 



In general character and nature of rock the pebbles in the 

 Jurassics have such a striking resemblance to those in the 

 glacial deposits as to force the conviction that they have either 

 come from the same or similar rock masses, from which the latter 

 were derived, or that the glacials have indirectly furnished them. 



Driftwood Theory. 



Since most of the carbonaceous material and silicified trees and 

 blocks of wood present in the Jurassic strata show distinct 

 evidence of transport, and not growth t'n situ^ it follows that this 

 material must have been drifted. Whatever may have been the 

 means by which the silicitied wood — assuming it to belong to a 

 period anterior to the Jurassic — was conveyed thither, the blocks 

 and masses of carbonaceous material were probably brought by 

 rivers into the Jurassic lake, on the surface of which they floated 

 far and wide till, becoming waterlogged, they sank to the bottom. 

 These masses of driftwood probably had entangled among them 

 pebbles of various kinds, and thus may have been the means by 

 which some at least of the pebbles were distributed among the 

 Jurassic sediments. 



Surface and Ground Ice Theory. 



The Jurassic deposits, as far as yet known, appear to be 

 wholly of freshwater origin, judging by the fossils hitherto 

 recorded. The fauna is represented by three species of fresh- 

 water mussel (Unio); while the flora comprises several genera 

 and species of ferns, and representatives of cycadaceous and con- 

 iferous vegetation. The deposits were, therefore, probably 

 formed in a large lake basin, or several smaller ones. This lake 



