196 The American Geoloqist. March, 1892 
« 9 
The gravels forming these deposits vary in size from sand to pieces as 
large as one’s fist, rarely being much larger; so it is probable that the 
glacier is now somewhat more extended than when they were laid down, 
and that the upper end of the cone where larger and more angular rocks 
would be found, is still under the ice some distance higher up the valley. 
The highest part of the bluff overlooking the Inlet is about 150 feet 
above tide, and occurs about where the glacier ended at the time of 
Prof.Wright’s visit in 1886 (see map in “Studies of Muir glacier,” shortly 
to be published in the National Geographic Magazine.) According to 
Mr. Russell’s idea they should become higher as we ascend the valley; 
as a matter of fact they become lower, being almost at water level at the 
point where the ice-point stood in 1890. Hence if Mr. Russell’s explan- 
ation is correct, and I think it very probably is, some 150 or 200 feet of 
gravel has been carried off from this point (and still more higher up the 
valley) since the former great retreat of the glacier. The angular rocks 
spread over the surface of these deposits were left there during the 
present retreat of the ice. 
Charpentier was the first one, I think, to notice that glaciers will ride 
over gravels* It is a mistaken notion that sands and gravels do not form 
asolid bed. When prevented from yielding laterally, or, what amounts 
to the same thing, when in large amounts, they offer a remarkably firm 
support. In soft, marshy lands it is customary to make satisfactory 
foundations for buildings by driving in piles, withdrawing them, and 
then filling the holes with sand. 
Cleveland, Ohio, Nov. 23d, 1891. 
Contrisution BY Mr. H, P. CusHING.T 
I have read your MS. with great interest. It clears up several doubtful 
points, but I must confess that the inain difficulty under which I labored 
in endeavoring to interpret the phenomena does not seem to be helped. 
That the deposits were formed by overloaded sub-glacial streams was 
clear tome. It was not clear, however, and is not yet, how they could 
be deposited in such a location. A glance at Reid’s map accompanying 
my paper, will indicate what I mean. Muir inlet is narrow and deep, 
and its shores are precipitous mountain slopes, except for the narrow 
space occupied by the gravels, which rest on an old forest soil. As 
stated in my paper, p. 221, suppose the ice to have retreated some few 
miles back, which is also required in your explanation. As the ice re- 
treated, sea water would follow it, certainly for a considerable distance, 
leaving merely a narrow sloping shore between the water and the mount- 
ain slopes. Howa stream could run along such a shore for any distance 
and build up such a deposit, I cannot conceive. After running at the 
*Essai sur les Glaciers, 1841, p. 72, foot note. 
+Mr. Cushing’s letter was not intended for publication, but permission 
was granted to use such portions of itas I thought best. The paragraphs 
given above are all that relate directly to the subject under discussion, 
and are presented with a few slight verbal changes. 
