The Idea of Glacial Erosion in America 207 
in any discussion of the sculpture of mountains by glacial agencies; 
just as the wearing of slopes and ridges by the weather goes with 
the erosion of valley bottoms by rivers. 
1907 — R. S. TARR. 
After a very detailed description of conditions observed in 
Alaska, concerning hanging valleys he says: “It is also true that 
this phenomenon is practically confined to regions of former glacia- 
tion. Together with the U-shaped valley, truncated spurs, and 
steepened main valley slopes, the condition of hanging valleys 
is reported not only from a wide area in Alaska and British Col- 
umbia, but in such other regions of former glaciation as the Sierra 
Nevada, the Rocky Mountains, the Finger lake valleys of central 
New York, the coast of Norway, the Alps, the Himalayas, and 
New Zealand. 
1908. 
Following a field study of glaciation in Scotland, Tarr’s con- 
clusions are illustrated thus: 
“Loch Ness is quite like one of the Alaskan “canals.” It is 
remarkably straight, has perfect truncated spurs, numerous hang- 
ing valleys and many waterfalls along its shores. The height of 
the hanging valleys above the lake bed varies greatly and seems 
to be proportioned to the size of the valley as one would expect.” 
“The measure of glacial erosion in many instances is hundreds 
of feet and in places perhaps as much as a thousand feet, thus being 
comparable to the erosive activity of the Alaskan glaciers and the 
continental glaciers in the Finger lake region of central New York.” 
CONCLUSION. 
The above quotations characterize the development of the idea 
of glacial erosion in this counrty; the list might be increased for 
many of the years as well as for the intervening periods. My aim 
has been to call attention only to the writings of men who have 
studied the subject most widely in the field. 
The Scottish Geographical Magazine^ vol. xxii, “The Sculpture of Mountains 
by Glaciers,” p. i. 
“Glacial Erosion in Alaska,” The Popular Science Monthly^ vol. Ixx, p. 113. 
