450 LTTE Vf OOTKN AVN OF NGLOLOG Na 
prominent hills. Conifers were abundant over parts of the area 
now treeless. 
4. A period of subsidence. Tide-water entered-the Golden 
Gate, filled San Francisco Bay, then spread out over the Santa 
Clara valley to the foothills. The whole region to the foothills — 
was reduced by erosion and deposition to a level. The waters 
extended up many of the streams. San Francisco was a little 
cluster of islands. Considerable deposits were laid down upon 
the ocean-side of the peninsula. 
5. A period of uplift to present level. One of the most 
interesting features of the last period is the remarkable erosion 
which has taken place in the deposits laid down in the periods 
just preceding. The topographic changes caused by erosion in 
the last twenty-five years have been so marked that, judging by 
the evidence of erosion in these latest beds previous to 1869, we 
must conclude, either that these beds have been subjected to 
erosion a very short time or that climatic or other conditions 
have become more favorable for erosion of later years. Quite a 
large number of hollows through which ran in 1869 county or 
farm roads now present impassable gullies, twenty-five to 
seventy-five feet deep. 
Ill.. THE AGE OF THE COAST RANGES. 
A casual examination of a topographic map of California 
reveals a lack of unity between the northern and southern Coast 
Ranges as regards their strike and the apparent direction of 
folding. The ranges occupying the coastal region of central 
California have a very uniform strike of northwest and south- 
east, suggesting a certain unity in the time and manner of their 
uplift. In Santa Barbara County we come abruptly upon a series 
of ranges running nearly east and west through Santa Barbara, 
Ventura. and Los Angeles counties. These ranges seem to 
possess a certain unity in having been elevated together. Was 
the movement synchronous with the elevation of the ranges 
further north ? A comparative study of one of the ranges of 
each group can hardly be taken as conclusive of the groups of 
