20 
GEOLOGY 
The plain is shaded at intervals by groves of oak trees, some of them overhanging the river, 
thus forming a desirable and beautiful camp ground. The river was not at its highest stage at 
the time of our visit; hut a Rrge body of water was flowing in the channel, and it was evident 
that a considerable quantity of snow remained in the mountains at the sources of the river. A 
diurnal rise and fall of the water was constantly observed, and is, without doubt, produced by 
the melting of the snow during the day. This water was remarkably pure and clear, and very 
cold ; its temperature seldom rising above 64° Fahrenheit, while that of the air varied from 
99° to 104° in the shade. A difference of over forty degrees between the temperature of the air 
and the water is not uncommon, and it becomes very evident when bathing in the stream during 
the day. The Indians who live on the hanks of the river do not, however, seem to regard this 
difference of temperature as sufficient; for it is their custom to prepare themselves for their 
hath by a preliminary baking in large underground huts, which have only one aperture, front¬ 
ing the stream. A fire being built in the centre of the apartment, the Indians crowd around 
it, and frequently add to the humidity of the atmosphere by pouring water on heated stones. 
After a violent perspiration is thus produced, they rush into the river with much gratification. 
During our stay at this camp we purchased fresh salmon of the Indians, who catch them in 
the river. It is probable, however, that they are not abundant, as the mining operations along 
the upper part of the stream and its tributaries sometimes load the water with impurities. 
Although the river was not at its lowest stage, it flowed only in the deepest part of its bed, 
and left bare and dry a broad “bench” of gravel and sand which is completely covered at high 
water. Portions of the river-bed above the fort are obstructed by great numbers of large 
blocks of granite, similar to that found below the fort. The floods of the river have swept over 
these masses, and rounded their surfaces until they are smooth and bright. 
River terraces .—Remains of ancient terraces are visible on both sides of the river, and may be 
recognized in the wood cut. These terraces appear to be three in number, and are at elevations of 
about thirty feet each. The third or upper terrace is obscure, and they are all much cut away 
and disguised by side ravines. 
Gold is found in the bed of the river in considerable quantity. It is mostly very fine scale 
gold, and it is difficult to separate it from the black sand, which is abundant and heavy. 
Groups of gold-washers and Chinamen were engaged all along the banks, either washing out 
the gold in a common pan or using the “ cradle.” A pan-full of sand and gravel taken up 
anywhere on the surface of the first bench of the river, would “ show color ” on being washed 
out. This term color has passed into general use among the miners, denoting the presence of 
just sufficient gold to be well recognized. One of the miners was working his claim with a 
cradle, and employed two Indians to dig and bring the auriferous earth and gravel. He was 
obtaining about one ounce per day. 
Some of the officers of the army at Fort Miller were constructing a canal along the bed of the 
stream, into which they were intending to turn the water of the river when at its lowest stage, 
and thus be enabled to obtain the sand of its bed, which was supposed to be extremely rich in 
gold. 
Granite .—Compact and granular granite is abundant in the vicinity of this place, and forms 
high ridges on both sides of the river. A specimen taken from a road-cutting just below the 
fort shows a fine grain and even distribution of the composing minerals. A portion of mica 
is replaced by hornblende, and the aggregation may be called a syenitic granite. It is an 
excellent building stone. 
