° a 
Gravel Deposits, Muir Glacier. —Russell. 197 
most a very short distance, it seems to me that it must have turned its 
course into the sea. That is, of course, with the relative levels remain- 
ing as at present. That is what puzzles me. With Muir glacier retreat- 
‘ing, and some distance away from this spot, how is a stream of water 
from the glacier going to be able to reach it? That Muir glacier did so 
retreat, and long enough to allow a forest growth on the mountains all 
around its basin to take place, is certain from the evidence there. (See 
my paper p. 223.) I thought it more probable that these gravels were 
deposited during a pause in the advance of the glacier which followed 
the recession, and when it was near this spot, simply because I was un- 
able to conceive how otherwise streams could have reached this spot 
with their gravels. If this point is well taken the natural conclusion 
would be that the conditions were in some way different from the pres- 
ent, and there being no evidence as to what that difference was, so far as 
I found, nothing remained but speculation. Moreover the deposit 
reaches its greatest hight where it rests against the mountain slopes, 
in one place 600 feet above the water. Again, as you can see from the 
plate accompanying my paper, where the glacier rests upon these depos- 
its they regularly decrease in hight as the ice increases in thickness, 
showing a diminution in hight toward the north. This may be due to 
the ice over it, but I doubt it. 
This then is my main trouble about accepting your explanation. If 
Muir glacier should now retreat five miles, sea water, not forests, would 
occupy the large part of the territory deserted by the ice, and a long 
stream running along a narrow shore parallel to the coast line and 
building up a thick deposit thereon seems to me “agin Natur,” as Josh 
Billings would say. 
Munchen, Germany, Dec. 9, 1891. 
The main objection which Mr. Cushing urges seems to be that 
the gravels are found on the borders of Muir inlet, but are absent 
from the central portion, where there is now deep water. If the 
explanation I have suggested is the correct one, we must suppose 
that the alluvial-fan spread out by the streams flowing from Muir 
glacier during its retreat, advanced southward and occupied the 
entire width of the valley, and formed a delta when the sea level 
was reached. Only the marginal portions of this deposit are 
now exposed; the central portion, and most of the surface, as 
suggested by Prof. Reid, having been eroded away. The greater 
erosion along the axis of the valley may have been due to the 
advance of the glacier which was capable of re-opening the 
central part of the channel where the ice current was deepest 
and most rapid, while remnants of the interglacial gravels were 
left at the sides, 
Washington, D. C., Dec. 22, 1891. 
