372 77/6 American Geologist. jmie. isoa 
Mr. Cushiug has recently well shown that it is quite incompetent 
to explain the whole difference between eight or ten feet and sixty- 
five feet.* 
3. • Actual Difference of Motion of the Glacier. 
A. Mr. Cushing first pointed out the connection between the 
reduced rate of motion found in 1890 and the remarkable changes 
of condition which had taken place since 1886,t and Mr. Upham 
has quite recently' attributed the apparent discrepanc}- in part to 
that same cause,+ but the extent of these changes and of their 
effect seems not to have been f ulh' shown. 
So much evidence of recent recession of the glacier has been 
given in all late accounts, and Mr. Cushing has so clearly pre- 
sented that evidence to the readers of this magazine? that little 
comment is necessar}-. Suffice it to saj' that the glacier has been 
retreating very rapidly for the last fift}- or one hundred 5'ears, 
leaving long stretches of moraine upon which no soil has formed 
and no plant grows, although the region is very favorable to vege- 
tation. The eastern half of the glacier seems to have very little 
motion, and to receive very little re-enforcement from winter snows. 
In fact, it is entirel}^ cut off' from its sources of supply, and re- 
treats down its valleys instead of up. Where we should expect 
neve we find a lake and the melting end of the glacier. Mr. Cush- 
ing saj's: "Hence the ice lying in Granite canon presents the same 
features as that in Main valley. The ice is inert. It has no 
feeders. It has disappeared from the upper portions of the A'al- 
ley while yet 13'iug in considerable force in the lower portion. It 
diminishes in altitude toward the head of the caiion, the highest 
point in the vicinit}' h'ing nearl}' three miles south of the entrance. " 
Again: "If there is the present slow flow of ice in Main valle}- 
alread}' spoken of, a flow in both directions from the highest point 
of the ice, there must be a corresponding slow flow of the ice back 
into Granite canon. " That this remarkable diminution is quite 
recent is evident from the moraines which extend from Granite 
*American Geologist, April, 1893, pp. 276-8. 
fAMERiCAX Geologist, Oct., 1891, p. 21G. 
:]: "Com pari son of Pleistocene and Present Ice-sheets," Ottawa meeting 
of G. S. A., Dec. 29, 1892. 
See also "Muir Glacier," S. P. Baldwin, Scientific American, April 9, 
1891, p. 227, and "Review of Prof. Reid's Studies of the Muir Glacier," 
in Amekican Geologist, Nov., 1892, p. 326. 
^AMEmcAx Geologist, Oct., 1891, pages 210-216. 
