SL ULDIMES, SHOU SIC UIDQUEIN TIES. 97 
only allows, but even demands, that a large part of the drift be 
stratified. It demands that the water issuing from the ice should 
carry beyond it such products of the glacial grinding as its cur- 
rents were able to handle. This is exactly what is taking place 
in glaciers today, andthe stratified valley drift extending beyond 
the great body of unstratified, argues that this is what took place 
when our drift was deposited. 
In searching for the explanation of the drift, therefore, if the 
facts concerning the drift and its relations are before us in their 
fullness, it would seem that there is little room for doubtful the- 
orizing. Geologists are now very generally agreed that glacier 
ice, supplemented by those other agencies which glacier ice calls 
into being, is the only geological agent which could have pro- 
duced it. But it is here repeated that this does not preclude the 
belief that at various times and places, in the course of the ice 
period, icebergs may have been formed, or that locally and tem- 
porarily they played an important role. It does not preclude 
the idea that wherever icebergs existed, berg deposits may have 
been made. It does not preclude the idea that pan-ice may have 
been an important factor locally. It does not preclude the idea 
that, contemporaneously with the production of the great body of 
the drift by glacier ice, the sea may have been at work on some 
parts of the present land area, modifying the deposits made by ice 
and ice drainage. Indeed, there is abundant evidence that such 
was the fact. There is abundant evidence that in some regions 
now covered by drift, the land stood lower than now, or the sea 
higher, when the drift was deposited, or since. 
The glacial theory does not deny that rivers produced by 
melting ice were an important factor in transporting and deposit- 
ing drift, both within and without the ice-covered territory. It does 
not deny that lakes, formed in one way and another through the 
influence of the ice, were locally important in determining the 
character of the drift. Not only does the glacier theory deny none 
of these things, but it distinctly affirms that rivers, lakes, bergs, and 
pan-ice must have co-operated with the glacier ice, each in its 
appropriate way and measure. Ro.Luin D. SALISBURY. 
