408 SUPPLEMENTARY INVESTIGATIONS IN THE GRAVEL REGION. 
The granite rock near Bowman’s is distinctly scored with glacial markings. This is the only 
point on this ridge where I saw unmistakable signs of ice action. A careful examination of these 
higher regions would doubtless develop much of interest in relation to glacial phenomena, but time 
did not allow of my pushing inquiries any farther in that direction. 
From several sources I heard of the existence of so-called “high gravel” on Fall Creek and 
Grouse Ridge. This is a district which is most easily reached from the Emigrant Gap station on 
the Central Pacific Railroad. It is hardly settled at all, and would be a difficult country to explore 
without animals or a camp outfit. I had the good fortune to meet, at Washington, a miner from 
the ridge who gave me such information about the deposits of gravel that I was satisfied I should 
not neglect anything of importance if I failed to go there. He spoke of shallow gravel banks, 
perhaps from ten to twenty feet in thickness, associated with granite boulders, and so situated that 
they might very well be of comparatively recent origin. 
Section IV. — The Washington Ridge, south of the South Yuba River. 
The careful exploration of any part of the gravel region lying to the south of the South Yuba River 
was not contemplated in the plan of my summer’s work. A hasty trip to Omega and its neighborhood 
was all that I expected to have time to accomplish. By way of Relief Hill I reached the town 
of Washington, which lies low in the caiion on the left bank of the South Yuba, and has no very 
close relations with the high gravel deposits, on the evening of the day I left Malakoff. During 
the next six days I visited Alpha, Omega, and Diamond Creek, and returned to Malakoff by way 
of Sailor Flat and Blue Tent. The gravel deposits known as Phelps’s Hill, Phelps’s Point, Jeffer- 
son Hill, Gold Hill, and Cotton (or Colton, as it is called in Raymond’s Report) Hill, which follow 
in order downwards from Alpha on successive spurs of the ridge, and which can be seen to good 
advantage from almost any prominent point on the ridge above Relief Hill, and from some of the 
high points near Omega, I was obliged to leave unvisited. The ravines are deep and steep, 
opposing very effectual barriers to easy communication between places which are in full view of 
each other, as, for example, Alpha and Omega, on opposite sides of Scotchman’s Creek. 
There can be no doubt of the former connection of the gravel between Omega and Cotton (or 
Colton?) Hill, and probably Relief Hill, prior to the erosion of the lateral valleys. Seen from any 
high point commanding a view of all the gravel, the deposits appear to be arranged in a regular 
series, nearly parallel with the present stream and having an easy grade downward towards Relief 
Hill. The series bears a very striking resemblance to that on the divide next north between Snow 
Point and Woolsey Flat. The deposits between Omega and Relief Hill are not capped with lava, 
the lower line of the lava at the present day being at a considerably higher altitude than the top 
of the gravel banks, excepting at Omega, where the difference of altitude is not so great. Indeed, 
if we were to regard alone the present appearance of these gravel beds, as they lie upon the high 
benches, there would be no difficulty in supposing them to have been deposited since the deposi- 
tion of the lava, at the time when the present South Yuba followed a channel twelve or fourteen 
hundred feet above its present bed. The objections to such an hypothesis, however, are too many 
and too important to be overlooked. The principal of these objections are, the total absence of 
tufaceous material in the gravel, the probable extension of the gravel under the lava in place at 
Relief Hill, and the certainty of the extension of gravel, similar in character and presumably 
formed at the same time and under the same conditions, under the lava of Malakoff and Woolsey 
Flat. 
My observations for altitude at Washington, Alpha, and Omega have not given very satisfactory 
results. The difference of bed-rock level at the two places last mentioned is certainly much less 
than my computations make it to be. Either Alpha is made too low or Omega too high; prob- 
ably the former. The greatest element of uncertainty is in the determination of the altitude of 
Washington, to which station alone the altitude of Alpha was referred. The total fall from Omega 
