l88 TJic American Geologist. September, i898 
trans-Greenland journey of Nansen in 1886. While adding 
something to glacial science, the work of these and other ex- 
plorers was more particularly along lines of geographic and 
meteorologic science. The close geologic study only began with 
the work of Chamberlin in 1894. This work has been carried 
on by Wright, 1894; SaHsbury, 1895; Barton and Tarr. 1896. 
In accumulating literature upon the living glaciers of the 
continent the papers by H. F. Reid and I. C. Russell, relating 
to the physics and phenomena of Alaskan glaciers, deserve 
special mention, with those of professor Chamberlin descrip- 
tive of the structure and behavior of the Greenland ice. Two 
writings of professor Russell of a general or descriptive char- 
acter, bring down to date a summary of our knowledge of the 
glaciers of the continent; the first on "Existing Glaciers of the 
United States," 1884, and the second a book of the past year, 
entitled, "Glaciers of North America." 
Down to a few years ago our knowledge of glacial physics 
was almost entirely derived from European study. However, 
the glaciers of the Alps gave but small or unsatisfactory help 
toward the explanation of some of the most important phe- 
nomena produced by the continental ice sheets, for example, 
the general sheet of till, drumlins, and the various aqueo-gla- 
cial deposits as eskers, kames, loess. The interpretations were 
largely inferential. More has been learned of the structure, 
behavior and work of our ancient ice sheets by the study of the 
Alaskan glaciers during the last ten years, and especially by 
the study of the Greenland ice cap during the last four years, 
than by all the study of the Alpine glaciers for the seventy 
years since they have been observed. 
The North American continent is recognized as the theater 
of the greatest display of glacial activity, not in the past only, 
but also in the present. It must become the Mecca of the 
foreign glacialist. Though much has already been ac- 
complished the work in America has only begun, and there is 
large opportunity for future investigation. 
About 1850 the Agassizian hypothesis became the glacial 
theory. Now the glacial geologists understand that the glacial 
genesis of the "drift" is no longer a theory but an established 
fact. They will do well to cease paying the deference to 
doubt, implied in the word "theory," and abandon its use in 
