AND TRANSPORTING AGENT—PREST. 343 
form, may have been transported from the continent in a block 
of river ice. 
As to the period of this age of transportation, it probably 
coincided with the retirement of the continental ice-cap and the 
elevation of Canada and the Arctic regions. Before this, the 
glacier ice was shed directly into the ocean in front. The 
elevation of the polar sea-bottom probably greatly strengthened 
the otherwise weak Greenland current, thus turning the debris- 
laden Labrador and Newfoundland ice to the southward. 
In connection with this, the beautifully precise theories of 
oceanic currents do not seem to apply fully to the Labrador 
and other northern currents, as the constant outpouring of polar 
waters is not met by an equal inflow. Even the most northern 
branch of the Gulf Stream is stopped at Spitzbergan, and returns 
by way of the east coast of Greenland, apparently forced to do 
so by the current which carried the “ Fram” in a southwesterly 
direction. The rapid rise of the north Polar regions seems to 
contribute largely to all the currents which flow outward from 
that point. The great depth of the Polar ocean as proved by 
Nansen would supply the surplus water needed, through the 
‘constant rise of its bottom. 
With the increasing amelioration of the climate of the north 
temperate zone, came the gradual retirement of the Labrador 
glaciers and the consequent cessation of the supply of the build- 
ing material to the Newfoundland banks. Therefore, the trans- 
portation of sea-borne detritus has been gradually lessening 
owing to the retirement of the source of ice supply, in spite of 
the fact that the power of the Greenland current had been 
probably increasing until it reached its maximum a few centuries 
ago, when the flow of ice to the southward was much larger 
than it is now. 
The building, or increase of submarine banks, is doubtless still 
going on, but the work in now confined to the neighbourhood of 
Greenland and northern Labrador. 
How long this ice-bearing Arctie current will continue to 
flow, must depend largely on the rise of the land in the polar 
