446 
TROPICAL NATURE 
VIII 
mortars have been found in similar gravel at a depth of forty 
feet. In Placer County stone platters and dishes have been 
found in auriferous gravels from ten to twenty feet below the 
surface. In Nevada County stone mortars and ground discs 
have been found from fifteen to thirty feet deep in the gravel. 
In Butte County similar mortars and pestles have been found 
in the lower gravel beneath lava beds and auriferous gravel ; 
and many other similar finds have been recorded. It must 
be noted that the objects found are almost characteristic of 
California, where they are very abundant in graves or on the 
sites of old settlements, having been used to pound up acorns, 
which formed an important part of the food of the Indians. 
They occur literally by hundreds, and are so common that 
they have little value. It seems therefore absurd to suppose 
that in scores of cases, over a wide area of country and over 
a long series of years, gold-miners should have taken the 
trouble to carry down into their mines or mix with their 
refuse gravel these articles, of whose special scientific interest 
in the places where found they have no knowledge whatever. 
It is further noted that many of these utensils found in the 
old gravels are coarse and rudely finished as compared with 
those of more recent manufacture found on the surface. The 
further objection has been made that there is too great a 
similarity between these objects and those made in com- 
paratively recent times. But the same may be said of the 
most ancient arrow and spear heads and those made by 
modern Indians. The use of the articles has in both cases 
been continuous, and the objects themselves are so necessary 
and so comparatively simple, that there is no room for any 
great modification of form. 
Human Remains in the Auriferous Gravels 
We will now pass on to the remains of man himself. In 
the year 1857 a fragment of a human skull with mastodon 
debris was brought up from a shaft in Table Mountain, 
Tuolumne County, from a depth of 180 feet below the surface. 
The matter was investigated by Professor Whitney, the State 
geologist, who was satisfied that the specimen had been found 
in the “ pay gravel,” beneath a bed three feet thick of cement 
with fossil leaves and branches, over which was seventy feet 
