30 TRANSACTIONS OF THE [DEC. 3, 
roots and branches of trees, rhizomas, reeds and grass, proves 
that the country must have been submerged and subjected to 
the influence of alkaline waters holding silicic acid in solution. 
The specimens from Napa Co., around St. Helena, where the 
‘“olass mountains” form an important feature, are of much more 
interest. 1. A specimen of wood-opal from Howell Montain, 
shows the organic structure most beautifully; in the closed 
tube small fragments yield a large quantity of water. 2. This 
bottle contains fibres of silicified wood, found about ten feet 
below the surface in an excavation in an eruptive conglomerate 
at Schramsberg, about four miles from St. Helena. The same 
conglomerate I found again at the road section from the toll- 
house to the Bradford Mine in Lake Co. The excavation was 
made for the purpose of making a cave in the mountain for the 
storage of wine. ‘These fibres examined under the microscope 
show the structure of cellulose fibres very plainly. About half 
a mile from the farm buildings, the remains of the trunks of 
three petrified trees are found in a ravine ; some of the speci- 
mens show also a desiccating process in the formation of fibres. 
The conglomerate is overlain by a tufaceous rock, which is also 
found to overlie the obsidian at the glass mountains north of St. 
Helena. It is therefore evident that the conglomerate, in which 
the specimen in question was found, must be of about the same 
age as the black obsidian, viz.: Tertiary. 
Ihave yet to present two other specimens, 3. a piece of petrified 
pitch-pine from Placer Co., and, 4. for curiosity’s sake, a piece 
of a petrified trunk, 180 feet long and 7 to 8 feet in diameter, 
found by Prospector Reese in Dead Valley, Mono Co.; this iso- 
lated trunk was taken up as a quartz ledge, supposed to be 
gold-bearing. 
Remarks were made by Dr. N. L. Brirron and Pror. D. 8. 
MARTIN, the former in regard to the micro-botanical structure, 
and the latter concerning the geological occurrence of these 
silicified woods. They are probably of the same age as those of 
Nevada Co., which are found similarly in gravel, etc., overlain 
by volcanic material, lavas or tufas, of late Tertiary age, as is 
the case along much of the west side of the Sierra Nevada. The 
underlying gravels and conglomerates are the ancient auriferous 
