342 DRIFT ICE AS AN ERODING 



for many days the upturned edges of the ice floes as they were 

 driven on shore, I saw very few with debris thus frozen in. The 

 deposits seen by me were often very unequally laid on, and 

 frequently absent near the bottom, where they naturally should 

 be. Sometimes an overturned ice pan showed sand, but for the 

 old idea that field ice obtained most of its debris from overhang- 

 ing precipices I could find no evidence. 



Conclusions. 



After having spent two months surrounded by ice fields, and 

 often beset on all sides with its difficulties, I have concluded 

 that very little of all the debris seen on the ice in polar regions 

 ever reaches the latitude of the Straits of Belle Isle, and also 

 that the Grand Banks are only receiving a fraction of the amount 

 of material formerly supposed. Consequently the Banks from- 

 Newfoundland westward aie almost solely the products of the 

 period of the greatest extension of ice erosion when the source 

 of the debris was our own provinces. It appears, therefore, 

 that those submerged banks are but the marine representatives 

 of the sand dunes and flats of New Jersey, Long Island, Cape 

 Cod and other places, and are principally the natural result of 

 greatly prolonged wave action on true glacial moraines ; with,, 

 however, this difference, that while the western deposits were 

 formed almost solely from the detritus from Apalachian and 

 local glaciers, the eastern have been added to in the later Pleis- 

 tocene by an Arctic current. The paucity of transported material 

 on the ice in the latitude of the Straits of Belle Isle convinces 

 me that it takes but a short time for storm and surf to clean 

 thoroughly all the ice brought down by the Greenland current. 

 Therefore, we cannot look farther north than Eastern Labrador 

 and Newfoundland for the source of any debris that may have 

 been added to the Grand and Sable Island Banks. In regard to 

 Sable Island, a recent paper by Dr. A. H. MacKay, on a fresh 

 water sponge found there, may furnish food for speculation as 

 to its origin. This, however, I do not think would affect my 

 conclusions. The sponge, if not an evolution from a marine 



