Climatic Changes Indicated by Glaciers.—Russdl. 358 
retreated considerably.” It is known that-the glaciers of Green- 
Jand were much more extensive during a former epoch than at 
present, and left records at an elevation of 3,000 feet above the 
present ice surface.* It may be suggested that the observations 
referred to by Dufour possibly relate to these ancient records. 
Weight of the Evidence: The observations summarized in this 
paper in reference to the Cordillera region, although unsatisfac- 
tory in many ways, indicate with a single exception which seems 
to have a special explanation, that the ice bodies in that region are 
retreating. This conclusion not only rests on direct observa- 
tions of several individuals, but is sustained by negative evidence 
as well. An advance of a glacier, especially in a forested country, 
is apt to be strongly marked, and would attract the attention of 
even a casual observer, but in no instance, with the exception 
reported by Dr. Hayes, and the slight extension on the border 
of the Malaspina glacier already mentioned, has a recent advance 
of the glaciers been reported. 
The fact that the glaciers at the head of Yakutat bay have re- 
treated several miles within the past one hundred years, as well 
as the still greater recession of the glaciers of Glacier bay during 
the same period, indicates the present general recession of the 
olaciers of the Pacific coast has probably been in progress for more 
than a century. During this time there must have been many 
minor oscillations which our imperfect observations do not de- 
tect but the fact that the general movement has been backward 
is well sustained. 
The shrinking of the glaciers of the west coast of North 
America, together with the conclusions reached by Prof. Dufour 
to the effect that the glaciers of both Kurope and Asia are reced- 
ing, indicate that the Greenland ice sheet is the only one in the 
Northern Hemisphere which is not now diminishing. 
Climatic changes: The advance and retreat of glaciers depends 
on climatic change. Glaciers, like enclosed lakes, record the 
result of the sum total of climatic changes which favor the re- 
tention of moisture on the land. In general it is safe to assume 
that increased precipitation will favor their growth and a rise of 
temperature lead. to their retreat. A general decrease in the 
glaciers of the Pacific coast suggests that other evidence of a 
secular climatic change should be found in the same region. ‘To 
*Am. Jour. Sci. 3rd ser., Vol. 24, pp. 100-101. 
