30 
NOTE. 
THE POST-GLACIAL PERIOD. 
Professor WARREN UPHAM, Assistant Geologist of the. 
United States Geological Survey, mm a paper “On the Cause 
of the Glacial Period,” makes the following remarks :— 
‘“‘ Measurements of the gorge and falls of St. Anthony show that 
the length of the post-glacial or recent epoch to have been about 
8,000 years. From surveys of Niagara Falls, Mr. C. K. Gilbert 
- thinks it to be 7,000 years, more or less.* From the rates of wave 
cutting along the sides of Lake Michigan, Dr. HE. Andrews estimates 
it at not less than 7,500 years. Prof. Wright obtains a similar 
result from the rate of filling of kettle holes among the gravel 
knolls and ridges called kames. Prof. B. K. Emerson, from the 
rate of deposition of modified drift in the Connecticut Valley, thinks 
that the time cannot exceed 10,000 years. A similar estimate 
is formed from the study of the Lakes Bonneville and La Hontan. 
The last great rise was contemporaneous with the last extension 
of ice sheets. Prof. James Geikie maintains that man in Europe 
made neolithic implements before the recession of the ice sheet 
from Scotland, Denmark and the Scandinavian peninsula, and 
Prestwich suggests that the dawn of civilization in EHgypt may 
have been coeval with the glaciation of north-western Europe, 
and D. Mackintosh cites the boulders in Wales and Yorkshire as 
proof that a period of not more than 6,000 years has elapsed.t Dr. 
Robert Bell refers to the preservation of the glacial striation and 
polishing. The striz are as fresh looking as if the ice had left 
them only yesterday. According to the astronomical theory which 
Croll and James Geikie have advocated, the glacial period was 
from 240,000 to 80,000 years ago, but it is wholly untenable in view 
of the geological evidence.’ 
* See also Victoria Institute Transactions, on these Surveys, vol. xix, p. 93. 
+ In a paper read before the Victoria Institute ; Zrans., vol. xix, p. 73. 
t American Antiquarcan. 
