ON THE GEOLOGY OF THE ISLAND OF AQUIDNECK. 621 
The fact noticed in the paper on the Topography of Aquidneck 
Island (see Vol. vi, page 518), that the streams on this island 
have the arrangement natural to a local water system, shows that 
the channels which separate it from the main land had been exca- 
vated before the last glacial period. Now, as we have already 
seen, these channels have a shape which can only be accounted for 
by supposing that they were formed by the excavating power of ice. 
Therefore we are compelled to suppose that there was an ice action 
anterior to the glacial period which gave way to make our present 
time. If this be true of this section of our fiord zone, it is likely 
to be true for a large part of the topography of our shores which 
is dependent for its shape upon ice action. It would be imprudent 
to rest so large a determination upon such a small basis of obser- 
vation; the question is, however, one which invites the consid- 
eration of all those who are interested in working out the 
history of our continent. Nor is the problem one of local 
interest alone; our whole conception of the conditions under 
which life has been developed and the successive sheets of 
strata laid down will be greatly modified by such a view of the 
past as would be forced upon us when we recognized glaciation as 
a constant factor in the evolution of the physical and vital his- 
tory of our earth. e need some conceivable agent whereby the 
life of the past could have been subjected to ever varying conditions. 
If it has been driven in endless chase from equator to poles 
by the alternating changes of heat and cold, these variations would 
have succeeded each other with startling rapidity. This view is 
consonant with all we know of life in the past ; it furthermore seems 
in the highest degree fitting that life, the product, the localization 
of solar energy, should find the spur that drove it onwards an 
upwards in the changes of its motive force. 
