GEOLOGY—VACAVILLE TO CHICO CREEK. 
23 
grass, but everywhere sustaining a growth of green vegetation, except where covered with the 
ripening wheat. A great breadth of surface was occupied by this crop, which the farmers told 
me generally produced from 35 to 40 bushels to the acre. The drought of the present season 
would reduce the yield to 25 to 30 bushels. 
The banks of the Sacramento, at Knight’s Landing and at Fremont, where we crossedit, are 
composed of fine alluvial earth, generally about 30 feet above the water-level at that time. A 
belt of timber lines either side; that near the water being willow, poplar, and sycamore, bound 
together by grape vines; further back the long-acorned oak, which, when the trees are crowded, 
assumes the torm of the white oak of the forests of the eastern States. 
No terraces are visible in the immediate vicinity of the Sacramento. Like those of Cache 
creek, its banks have been formed by the stream when at nearly its present level, and belong 
entirely to the present era. 
The water of Feather river, at the junction with the Sacramento, is so highly charged with 
sediment, derived from the gold diggings on its tributaries, that it is rendered quite opaque, 
and has a color as decided as that of the rivulets in the streets of our towns during a thunder¬ 
shower. 
The country bordering Feather river to Marysville presents no new geological features. No 
rock is seen in place, and the banks of the stream are like those of the Sacramento, composed 
of fine loamy earth, with very few pebbles as large as walnuts. The soil is excellent, and 
melons and various crops are growing with considerable luxuriance. 
The red color of Feather river, so noticeable at its junction with the Sacramento, is for the 
most part, derived from the Yuba, which, at Marysville, where they unite, has deposited such 
quantities of sediment as to render its navigation impossible at a point considerably below 
where boats could formerly run. 
The floods of the Yuba, which have occasioned so great destruction of property at Marysville, 
have left piles of drift-wood forty feet above its bed. 
The want of building stone is severely felt in this vicinity. The houses in the town, since 
the fires have swept away relays of wooden structures, have been all built of brick, and the 
wharf at the steamboat landing is built of bags of sand. 
From Marysville, up the feather river, to Hamilton, we found no rock in place, and no trans¬ 
ported masses of any considerable size. The soil is generally a fine sandy loam near the river, 
evidently fertile, and supporting a dense growth of vegetation; while the plains back from the 
streams are frequently gravelly, and less productive, bearing a thin crop of coarse grasses, and 
scattering trees of the two species of oak which have been mentioned, with occasional clumps 
of manzanita. 
The gravel and rolled stones in the beds of the streams are generally composed of some form 
of trappean rock, usually trap, porphyry, trachyte, &c., more rarely of quartz. These are, 
probably, principally derived from the Sierra Nevada, but in part also from Sutter’s buttes, 
which are but about 10 miles distant from the road which we followed. 
These mountains have been distinctly visible since leaving Cache creek; first as a single 
peak, subsequently showing two others. They form, however, but a single mountain mass, 
and should be denominated by a common name. From specimens brought from there, as well 
as from the description given of them by Professor Dana, (Geol. Expl. Exped.,) we learn that 
they are of volcanic origin, and not of recent date. 
They now rise like islands in the plain on which they stand, the highest point having an 
altitude of about 1,800 feet above its general level. The alluvial deposits of the valley, which 
