52 Proceedings of the Royal Society of Victoria. 



on land. The mudstones containing the pebbles and sandstones 

 between them at locality 1, and as far as noticed elsewhere, are 

 essentially part of a continuous series extending both above and 

 below them, under generally similar conditions, undoubtedly 

 marine. We are therefore limited to transport by floating ice, 

 not by land ice. With this agrees the disturbance of the fine 

 sandstone near the top of the series at locality No. 1, which 

 would be ascribable to stranding of the floating ice. The 

 disturbance is quite different from that which I have before 

 ascribed to differences of rigidity under folding in the Ordovician 

 rocks. ^ 



While icebergs from extensive ice sheets and glaciers often 

 carry little foreign material compared with their bulk, the case is 

 essentially different with shore ice and river ice. Nor are the 

 glaciated stones sufficiently numerous or distinct to regard the 

 ice as the only agent operating. 



The following description of the Yukon by Mr. I. C. Russell 

 seems to fulfil the conditions of this case. 



The Yukon " freezes deeply during the winter and the ice near 

 its borders, especially when it is broad and shallow, rests on the 

 bottom and has large quantities of stone and boulders attached 

 to it. All except the largest of the tributory streams freeze to 

 the l^ottom and also furnish vast quantities of pebbles for ice 

 transportation. When the rivers break up in the spring, the ice 

 with its loads of stone is floated down stream, and melting, as it 

 goes, distributes pebbles and boulders over the bottom of the river 

 and in places where at other times fine sediment is deposited. 

 In this way it is conceivable that a clay filled with boulders 

 might be formed which would simulate true boulder clay in 

 many ways. Certain boulder clays along the Yukon and the 

 Lewes are described elsewhere in this paper, which, as there 

 stated, may have been formed in the manner here suggested. "- 



Now, it will be evident that the formation of such a deposit 

 resembling boulder clay will not he limited to the course of the 

 river i)ut may occur as far as the ice can reach in floating out to 

 sea and that shore ice may behave in just the same manner. The 



1 Proc. Royal Society Vic, vol. xiv., pt. ii ii.s. 



2 Bull. Geol. Soc. Amer., vol. i., 1890. 



