Bouve.J 
224 
[April 17, 
about inches, its shortest 4 inches. Transversely, it is quite 
circular. It is of granite, not unlike that of the surrounding coun- 
try. There is no reason to question the truth of the tradition. 
To account for the phenomena presented by the pot holes de- 
scribed, it is necessary to recognize that when the great glacier 
lay over the land, many hundreds of feet in depth, during the 
summer, particularly towards the close of the period, rivers flowed 
over its surface, as they now do over the glaciers of the Alps. 
As there, crevasses were formed in the ice, into which the water 
poured and worked passages to the bottom of the great sheet, dis- 
charging itself in torrents, often conveying stones and other mo- 
raine matter to the rock surfaces below. Such passages in modern 
glaciers become somewhat circular in form and are hence called 
wells. They are also called moulins, the latter name from the 
noise made by the rushing waters in the ice, being not unlike 
that of a mill. The water, and the material conveyed by it through 
such wells of the great glacier of our continent, must have smoothed 
and worn rapidly away the rock surface on which they impinged, 
often causing, by the same kind of action as is witnessed under 
falls of water in some of our rivers, holes in the rocks of like char- 
acter as those now under consideration. Of course the action 
of the water and material conveyed by it would be immensely more 
rapid in forming such holes, falling, as they undoubtedly did, 
from a great height and striking upon the rocks below with intense 
force. This would lead to the abrasion of the rock, by any ro- 
tating stones lodged in the hollows, so much more powerful than 
any action we know under falling waters of the present day, as to 
render estimation of the result incalculable. 
It is doubtful, however, to the mind of the writer, if circum- 
stances often favored the formation of pot holes directly beneath 
such a fall and where its full force would be felt. He is impressed 
with the view that if this were the case they would not be found 
having the form they horizontally present. 
It has, indeed, been thought strange that, as the ice moved con- 
tinuously on, the holes were not found generally elongated in the 
direction of the movement of the glacier rather than circular. 
Such thought, however, is only consistent with the presumption 
that the holes were made just where the water first fell upon the rock 
surface below. Far more reasonable is it to suppose that the holes 
were formed somewhat distant from this place, where the masses of 
