MOHAWK LAKE BEDS. 
407 
of these ancient streams. One very remarkable thing noted 
is the finding of fossil trees standing upright on the banks 
of one of these channels, having been overwhelmed by a 
mud flow of lava, such as many of the flows of breccia and 
tufa undoubtedly were, without being displaced. 
On page 445 Mr. Browne says: 
“ If Professor Le Conte’s view is correct, and the bearing 
of the axis of upheaval is north and south and the tilt to 
the west, one should expect to find in following the sinuous 
course of the tilted channel, first, the original grade main¬ 
tained wherever the course is north or south; second, a 
greatly increased grade wherever the course is west; third, 
little or no grade wherever the course is east, * * * 
more data are wanted to settle the question of tilting. How¬ 
ever, it may be said that the evidence, as far as it goes, is 
against any considerable increase in the slope of the Sierra 
flank—decidedly against an increase large enough to account 
per se for the two-thousand-feet-deeper cutting of the modern 
river.” 
The most decisive grade would be an easterly one. Un¬ 
fortunately, none of these channels appear to have such a 
course, even for a few miles. 
The last important paper is by Mr. Becker, “ The Struct¬ 
ure of a portion of the Sierra Nevada” (I). Mr. Becker 
accounts for the late elevation of the Sierra Nevada by means 
of distributed faults, of which he has found evidence during 
the past season. His explanation of how this occurred is 
somewhat elaborate, and the reader is referred to the original. 
Resume. 
Mohawk Valley is the bed of a Pleistocene lake caused by 
the damming up of the canon of the Feather River by a 
flow of andesitic lava. 
Glaciers existed contemporaneously with the lake. 
A line of recent faulting extends across the lake beds in a 
northwesterly direction. This line of faulting appears to 
