36 THE AURIFEROUS GRAVELS OF THE SIERRA NEVADA. 
a small fragment of a dark-colored argillaceous and slightly micaceous slate, 
bearing upon it the impression of an Ammonite ; or, if not an Ammonite, at 
least some chambered shell, which had an unmistakable Secondary look. As 
this was an isolated specimen, and the fact that it came from the rock in 
place at the specified locality could not be definitely ascertained, it was not 
regarded as being of much value, except that it strongly encouraged the ex- 
pectation that, after much searching, fossils might yet be found in the slates 
which had so far seemed quite barren of all traces of organic life. 
Meantime, the fossils obtained from the limestone in Shasta County, at 
Bass’s Ranch, first noticed by Dr. J. B. Trask, in 1855, were examined by 
Mr. Meek, and referred by him to the Carboniferous,* in accordance with Dr. 
Trask’s previously expressed opinion. This was in 1862. The region in 
which these fossils were found was, however, far from the gold region proper, 
and our knowledge of the stratigraphical relations of the rocks of the Sierra 
was not sufficient to enable us to judge how far the recognized age of this 
limestone mass might have a bearing on that of the auriferous belt. 
The same was the case, to some extent, with the discoveries of Triassic 
and Jurassic fossils made by the Survey in Plumas County, in 1863.¢ The 
locality was so circumscribed in extent, the stratification so disturbed, and 
in part obliterated, that no satisfactory idea could be got of the structural 
relation of the beds in which these fossils were enclosed to the main body of 
the auriferous belt. It was, therefore, extremely desirable that fossils should 
be found in the heart of the gold region proper, in immediate proximity to 
the great quartz veins, and in such a position that there could be no possibil- 
ity of error in connecting the results of the determination of their geological 
age with the occurrence of the larger and most important localities and 
rocks in which auriferous quartz was being mined. The Ammonite obtained 
from Mr. Conness came from a central point in the mining region; but, 
being a loose specimen, could not be accepted as anything more than an 
indication. 
It was on the Mariposa Estate, in the immediate vicinity of the great 
quartz vein then extensively worked, that Mr. King found Belemnites in 
three different localities. At one of these, Miss Errington, a lady residing 
* See Geology of California, Vol. I. p. 326. 
7 1. ¢. 308. 
t On the English trail, at Hell Hollow, and near the Pine Tree Vein, within twenty feet of this great 
mass of quartz. Geology of California, Vol. I. p. 482. 
