498 Valk NY, IO UE INE EIR 
of the National Museum, who reports as follows concerning 
them: 
Six species of plants are represented : 
Fern, probably P/ervzs, but very fragmentary. 
Populus, female Catkin. 
Alnus, fruits and leaves. 
Castanea, sp. leaf. ‘ 
Vaccinum, sp. single small leaf, 
Arbutus, sp. Numerous well-preserved leaves and fragments. 
I have not been able to identify any of the above mentioned material with 
anything from California. The forms all have a very modern aspect, the 
more abundant being the Arbutus, which is close to the living form. 
As to the age, I do not think there can be any doubt about their being 
Pliocene. They certainly cannot be older. 
The conclusion of Professor Knowlton that the plant remains 
in 1897 are certainly not older than Pliocene, would not appear 
to conflict with the conclusion of Merriam as to the Middle 
Neocene age of the formation as a whole, inasmuch as these 
leaves came from near the top of the formation, as exposed near 
Kirker Pass. Overlying the plant remains above noted, are 
some layers of volcanic pumice (2), of which specimens were 
collected. An examination of this material under the micro- 
scope shows that it has been much altered by infiltrating waters, 
but that the glass has a rhyolitic composition, as indicated by its 
low index of refraction. A chemical analysis of one specimen, 
No. 345, shows, as does the analysis of No. 399, that the pumice 
has undergone leaching, resulting in a loss of silica and alkali. 
All of the plant remains obtained by myself at Kirker Pass came 
from the Hyde Ranch, and were collected ina field west of the 
road from Cornwall to Summersville. The locality of 1897, is 
on the north slope of a low hill, and about 430 meters south of 
the house of George South. 
The San Pablo formation, at Corral Hollow, has afforded 
nineteen species of fossil plants. A few of which have been 
identified in the Auriferous gravels flora. The plant beds at 
Corral Hollow, from which the specimens came which I col- 
lected, underlie andesitic tuffs, and conglomerates, which are 
