58 REV. PROF. G. F. WRIGHT, ON THE INFLUENCE OF THE 
than Niagara as the time required for the retreat of the ice 
from the Mississippi watershed to its removal from the valley 
of the Mohawk in Central New York, amounting perhaps to 
1.000 or 2,000 years. 
Upon measuring a section of the eroded valley 5,000 feet 
long, I was able to determine the total amount of work done by 
the stream since the beginning of its flow. Twelve years ago 
the village, in constructing waterworks, turned the course of 
the stream into a new channel, cut for it 500 feet long, so that 
we are now able to estimate the rate at which this stream 
under favourable circumstances is carrying away material from 
the valley. As the full calculations and results are soon to 
be published elsewhere, I shall not go into details here, but 
will simply say that they are entirely inconsistent with a 
supposition of more than 10,000 or 12,000 years as the period 
of the stream’s activity. The calculations fully corroborate 
those which have been made concerning the age of Niagara 
Falls. The supposition that this creek has been at work for 
100.000 or even 35,000 years is erroneous in view of its present 
known activity. 
3rd. The small extent to which the innumerable lakes, ponds, 
and kettle-holes which dot the glaciated region have been filled 
up leads to the same conclusion. Such are the forces at work 
to drain and fill up these depressions, that a few thousand years 
is all that is required to bring them into their present condition. 
Many of them have been already obliterated, while the others 
show that the obliterating forces cannot have been in operation 
many thousand years.* 
4th. Another confirmatory witness to the short time which 
has elapsed since the Glacial Epoch is found in the small extent 
to which the surface of limestone strata, which were once 
highly polished through the action of glacial ice, have since that 
time been disintegrated and eroded by sub-aerial agencies. 
The activity of these agencies can be seen on the tombstones in 
any ancient cemetery and in the exposed walls of old buildings. 
Now, in the glaciated region, where polished limestone surfaces 
have been exposed, there are frequently in close proximity 
areas that have been protected by superincumbent large boulders 
which are standing on a low pedestal left in the process of 
surrounding sub-aerial erosion. But these pedestals are never 
more than two or three inches in height, showing that a few 
thousand years would be amply sufficient to produce the results. 
* See Author’s Ice Age in North America. 
