390 Canadian Record of Science. 
the upper limits of glaciation in the mountain ranges of 
America indicate the thickness of a continental ice-sheet. 
They probably indicate only the upper limit of the abrasion 
of local glaciers. (2.) Hence it 1s computed that the thick- 
ness of a continental glacier flowing radially outward in 
all directions from the Laurentian highlands of Canada, 
amounted to two miles; and in connection with this it is 
stated that the maximum thickness of a continental glacier 
of the great Cordilleran glacier of the west has been 
estimated to be about 7,000 feet, an entirely different thing 
and referring to the maximum depth of a local glacier 
traversing deep valleys. (3.) It is admitted that the 
assumed continental glacier could not move without an 
elevation of the Laurentian highlands to the height of 
several thousand feet, of which we have no evidence, for 
the cutting of the deep fiords referred to in this connection 
must have taken place in the time of Pliocene elevation of 
the continents before the glacial period. (4.) The Upper 
and Lower Boulder drift, so different in their characters, 
are accounted for on the supposition that the former comes 
from material suspended in the ice at some height above 
its base, the other from that in the bottom of the ice. In 
like manner the widely distributed interglacial beds holding 
remains of land plants of North temperate character, are 
attributed to such small local occurrences of trees on or 
under moraines as appear in the Alaska glaciers. (5.) The 
rapid disappearance of the ice is connected with a supposed 
subsidence of the land under its weight, though from other 
considerations we know that if this was dependent on such 
a cause, it must have been going on from the first gathering 
of the ice, so that the required high land could not have 
existed. All the evidence, however, points to subsidence 
and elevation owing to other and purely terrestrial causes, 
and producing not produced by the glaciers of the 
Pleistocene. 
The paper is short and clearly written, and I think will 
convince any intelligent reader that the writer could not 
have arrived at the conclusions he indicates except by as- 
suming the continental glacier as a foregone conclusion. 
