Sedimentary formations. 43 
FOSSILS. 
No fossils were found in the Eocene limestone, but a number were 
found in the limestone and chert pebbles of the conglomerate beds. 
The following forms, which are mainly Carboniferous, were identified 
by Prof. Eliot Blackwelder: 
Fossils from the Claron limestone. 
Productus sp. Spirifer sp. 
Fenestella sp. Zaphrentis sp. 
Lithostrotion sp. Crinoid stems and bryozoans. 
Rhynchonella sp. 
They show only that the Claron sediments are post-Carboniferous. 
STRUCTURAL RELATIONS AND THICKNESS. 
The relations of the Claron limestone to the underlying Pinto 
sandstone have been discussed. On the upturned and eroded edges 
of the Claron limestone lie the Tertiary lavas in nearly horizontal 
beds. 
The dips of the Claron limestone are slightly less than those of the 
Pinto sandstone because of their greater distance from the laccoliths. 
In a few places the beds are nearly horizontal, as south of Joel 
Springs Canyon and at Mount Claron. 
A large amount of faulting has taken place in Eocene areas, some 
of which has undoubtedly remained undetected because of the 
similarity of different parts of the formation. Most of it dated 
after the laccohthic intrusion and before the later lavas were poured 
over the area, as shown by the fact that certain of the limestone 
areas are much faulted while the adjacent lava beds are undisturbed. 
A few faults traverse both formations indiscriminately, thus showing 
a later period of faulting. 
The thickness of the Claron formation varies in different parts of 
the quadrangle, owing to erosion both before and after the laccolithic 
intrusion. The average thickness is about 1,000 feet, but all esti- 
mates are largely vitiated by faulting. 
CONTACT METAMORPHISM BY EFFUSIVES. 
Adjacent to the lavas the limestone has a layer of white, gray, 
or red chert, chalcedony, and moss agate or jasper, which is some- 
times 10 to 15 feet in thickness. The red moss agates and jaspers 
are colored with iron. With these cryptocrystalline varieties of 
quartz is often associated a white powdery calcium carbonate, 
apparently deposited by hot springs. This is especially abundant 
north of the Eightmile Hills. The same powdery carbonate is 
frequently associated with the ore deposits. 
