Climatic Changes Indicated by Glacters.— Russell, 335 
above may be valid, but it seems to me for various reasons, that 
but little weight should attach to it. 
The comparison of the retreat of glaciers on the west coast 
with the rise and fall of the lakes of that region, more especially 
of the enclosed lakes, would be instructive, but here again, as in 
the case of the weather records, no records covering a suffi- 
cient length of time are available. Observations on the rise and 
fall of Great Salt lake show many fluctuations, but no general 
decrease which is comparable with the retreat of the ‘Cordilleran 
glaciers. * 
The geological records of lakes Bonneville and Lahontan show 
two maxima separated by a minimum, which latter indicates a 
period of desiccation, and followed by a second minimum which 
extends to the present day. The retreat of the glaciers on the 
west coast seems in harmony with this record. The desiccation of 
the lakes referred to has accompanied the retreat of the glaciers 
on neighboring mountains, but -has been more rapid. It is be- 
lieved that the lakes of the Great Basin had their last maximum 
at the time the Sierra Nevada was covered with glaciers. A gen- 
eral decrease in the glaciers appears to have accompanied the de- 
siccation of the lakes and is still in progress. 
The retreat of the glaciers on the Pacific coast, as shown by 
rough quantitative determinations at Yakutat and Glacier bays, 
has been in progress for not less than one hundred years. The 
character of the forests about the extremities of the glaciers of 
Lynn canal, show that the ice streams have not advanced beyond 
the barren areas in which they now terminate, within at least one 
hundred and fifty or two hundred years. In the case of David- 
son glacier, the barren area intervening between the ice and the 
encircling forest is about half a mile wide. If this retreat was 
accomplished within one hundred years it would show that the ice 
foot receded at the rate of about two feet per year. + 
Similar conclusions have been reached in reference to other 
glaciers in the same region and, although definite measurements 
*The fluctuations of Great Salt lake have been discussed by G. K. 
Gilbert, who shows that they coincide but imperfectly with observed 
variations in temperature and precipitation in the same region. U.S. 
Geol. Surv., Monograph No. 1, pp. 280-248. 
TThis is an exceedingly rough estimate for the reason that the breadth 
of the barren area about the foot of Davidson glacier has not been 
ee The statement that it is half a mile wide is from eye estimate 
simply. 
