448 LTTE, fiQUORNALTOR NGI OLE OGY: 
Lawson,* shows the strong resemblance of San _ Francisco 
Bay, of Rodeo Lagoon, Tomales Bay, Walker’s Creek, Drake’s 
Bay, Ballenas Bay, the Valley of Lake Merced, etc., to sunken 
and submerged valleys. 
There is another topographic feature which must not be over- 
looked. Standing upon the hills near South San Francisco 
station where a comprehensive view can be obtained of the line 
of hills extending from Seven Mile Beach to Redwood City, 
their summits can be seen to present a remarkably even hori- 
zontal line. Examined on the ground the top of this line of 
hills has the aspect of a dissected plateau, from which rise a few 
sharply conical knobs. These have the appearance of remnants 
left by the eroding waters which planed off the top of the hills. 
Dr. Lawson has also pointed out that the whole coast has 
recently stood for a considerable time at an elevation of 1600 to 
2100 feet below its present level. Evidence of this is seen in 
the level summit of the main ridge to the north of Black 
Mountains. 
The deposits.— Turning to the deposits we find three distinct 
sets exclusive of those now forming. 
Of the first only remnants remain. They are the deposits 
corresponding with the topographic features last mentioned. 
All along the level summit of the foothills no deposits are 
noticed until Black Mountain is approached; then the summits 
of the foothills are more or less covered with water-worn bowlders 
of metamorphic rocks. Bowlders do not occur further north, 
probably because in that direction the foothills are separated 
from the main ridge of the mountains by the long deep valleys 
of Bear Creek, Crystal Springs, and San Andreas, while near 
Black Mountain the foothills'are connected with the mountains 
which must have supplied all such material. 
The second class of deposits are stream and wind deposits. 
These are quite prominent in the benches in the streams. They 
appear as sand dunes on the ocean side of the mountains buried 
* Univ. of Cal., Bull. Dept. of Geol., L., 263. 
?Univ. of Cal., Bull. Dept. Geol., I., 115-160. 
