Vor. IIT] ANDERSON—FURTHER STRATIGRAPHIC STUDY 7 
other complex features have hitherto escaped attention. How- 
ever, these points can not be taken up in the present paper. 
Among the divisions enumerated by Whitney are the 
Panoche, the San Carlos, and the Estrella, which, he says, are 
individualized by certain low passes extending across the 
range. Considering these divisions as separate islands or 
groups, it would ultimately be necessary to subdivide some of 
them at least into two, or perhaps three sections for special 
epochs of the Tertiary, with waterways extending from the 
basin of the Great valley to that of the Salinas. One of these 
open channels lay along the course of the west branch of the 
Jacalitos and the upper Warthan creeks, and one along the 
Los Gatos creek and the San Benito river, thus dividing the 
San Carlos division into three sections or subdivisions for at 
least a part of the Tertiary. Ina complete or detailed study 
of the range, other channels and the islands separated by them 
at one time or another would require notice, but those men- 
tioned are perhaps sufficient to illustrate the nature of the 
problem. 
In all probability, as time went on during the successive 
periods or epochs, certain geographical changes occurred 
which resulted in either increasing or decreasing the width 
and number of these transverse channels; and these results 
could have been accomplished by simple changes in elevation. 
It appears that during the Miocene period only the Warthan 
channel was open, while during the Pliocene both the Warthan 
and the Los Gatos channels were in existence, as is shown by 
the distribution of the Miocene and Pliocene sediments along 
them. 
The islands and channels that existed during the Eocene 
can not be so easily discerned, but undoubtedly there were 
many. 
Eocene sediments run well into the range, if not across it, 
on the borders of the Livermore and Panoche valleys; and 
the same is probably true in the neighborhood of the Antelope 
and the Cholame valleys, as well as farther south. 
Probably this statement of the insular condition in Tertiary 
times is sufficient to illtstrate some of the factors that affected 
