*yt 
RANGE OF THE GRAVEL REGION. 5 
Gabriel Range, and in some of the valleys of the San Bernardino Mountain 
are, or have been, worked for gold at various times during the winter season. 
They are not the scene of extensive and permanent mining operations, like 
those hereafter to be described; but rather of the nature of the ordinary 
placer-mining gravels; that is, of local origin and comparatively unimportant. 
The deep canons of the rivers of the extreme northern counties — especially 
the Klamath and its branches — contain large amounts of gravel, which have 
been, at times, quite extensively worked for gold, and in places with large 
profits. This region has never been systematically explored by the Geo- 
logical Survey, but there is no reason to suppose that these gravels differ 
from ordinary river deposits of detrital origin, except in being on a scale of 
magnitude corresponding with the depth of the cafions. They have not 
been, up to the present time, so far as known to the writer, the object of 
systematic and permanent mining operations, such as those carried on in the 
gravel-mining region proper, and they will, therefore, not be included among 
the topics discussed in the present volume. Yet it will be readily admitted 
that both these more northern as well as the southern gravels demand a 
careful examination, especially with a view to forming some better idea than 
we now possess of their probable future importance. 
The gravel region proper, or that portion of the western slope of the Sierra 
Nevada here to be especially described, may be said to be nearly conter- 
minous with the belt of auriferous slates, the range of which has already 
been indicated in the preceding chapter. In the region where granitic 
rocks prevail, whether in the southern portion of the Sierra, or along the 
crest of the range, the gravels are local in character, and are not washed for 
gold. This statement, however, needs some explanation and limitation, and 
this will be found a little farther on, when describing the nature and range 
of ordinary placer-mining operations. The gravel-mining region proper may 
therefore be said to begin in Mariposa County and to extend into Plumas, 
as far as the line already indicated as marking the limit beyond which the 
slope of the Sierra is entirely covered with volcanic material. But all por- 
tions of the area thus designated are by no means equally important either 
in respect to the amount or the richness of the gravel which they contain. 
Mentioning the counties in their geographical order from north to south, we 
find the importance of the gravel deposits increasing as we go from Tuo- 
lumne to Calaveras, and thence to Amador. El Dorado, Placer, Nevada, and 
Sierra are the great mining counties, and there is a gradual falling off in 
