Geology and Natural History. 71 
the range, or about north 30 deg. east, and south 30 deg. west. 
Lines of cleavage cross these, running nearly parallel with the 
or 
the granite may be, it still possesses these lines of cleavage, whic 
require only simple conditions of moisture, time, etc., for their 
iving 
? 
rise to those narrow-slotted cafions, called “ devil’s lanes,” “ devil’s 
In many places, in the higher portion of the Sierras, these slot- 
ted cafions are filled with snow, which I thought might prove to 
place were only sixteen feet apart. I set a short, inflexible stake 
im the ice, so as just to touch the tightly-drawn line, by whic 
teenths of an inch. At the end of four days, I again examin 
and found that the whole downward motion was thirteen-sixteenths 
of an inch, showing that the flow of this glacier was perfectly 
regular, 
n accounting for those narrow-lane caiions, so common here, I 
always referred them to ice-action in connection with special con- 
ditions of cleavage, and I was gratified to find that their forma- 
tion was still going on. This Hoffman glacier is about 1,000 feet 
long by fifteen to thirty feet wide, and perhaps 100 feet deep in 
the deepest places. : 
I go back to the mountains to complete these observations. 
These are the first fruits, and the rest of the crop I will bring in 
when I come to study in the Coast Range.— Overland Monthly 
Jor December, ni 
3. Return of the Yale College Geological Expedition.—Professor 
Marsu and party returned on the 7th of December from the Rocky 
