Glaciers and Glacial Radiants — GlaypoU. 75 
by a glacier so that on the disappearance of the ice small lakes 
may occasionally appear or fiords of no great depth ensue, there 
is not sufficient evidence that lakes and fiords are generally due 
either entirely or chiefly to glacial erosion. And when the 
theorist advances to the position that most of the lakes in 
glaciated districts owe their origin to this cause and even main¬ 
tains a similar view regarding the beds of the great lakes of 
North America his position becomes very unsafe. He is then 
carrying the effects of a small cause beyond all due bounds. 
His zeal and enthusiasm have got the better of his judgment. 
In like manner the advocacy of an ice-cap covering the pole 
and extending far down toward the equator can scarcely be re¬ 
garded as the product of, calm calculation. There are no data 
of sufficient importance yet brought forward to warrant so vast 
a deduction. The past history of the earth reveals many start¬ 
ling facts but none that justify the construction of a shell of 
ice 6,000 feet thick at the pole and the consequent lowering of 
the sea-level by the conversion of so vast a quantity of its 
water into cloud, snow and ice. 
On the other hand it is impossible to explain the observed 
phenomena, especially those of the North American Continent, 
by the existence of mere local glaciers. The marks of the ice- 
chisel are too numerous, too wide-spread and too nearly uniform 
in direction to allow of so partial a cause. Local glaciers on 
the highlands could never produce a general striation from the 
northward on the rocks in the middle and northern United 
States. Marks so produced would necessarily radiate from the 
centre of production and would not usually become confluent. 
Nor on this theory can we explain the existence of ice-printing 
on the surface of the rocks in the midland states — an almost 
level district, where no mountains and few hills can be found 
to afford gathering-ground for ice and snow. This difficulty 
has led to the advocacy of floating ice as the glaciating agent in 
regions where it was apparently impossible that water in suffi¬ 
cient quantities could exist. 
The wisest course will therefore be to abandon both extremes 
and seek some middle ground. In so doing several conditions 
must be taken into account. 
One of the chief conditions necessary for the production of a 
