Oscillatiuns of the California Coast. — Fairbanks. 229 
ther south, exoept olf Pt. Conception, where it is only 35 miles 
across, the plateau widens greatly, sweeping outside of the 
Coast islands which lie off southern California, where a 
width Qf 150 miles is shown. The islands and sWoals are 
dotted over this submerged region in a manner approxi- 
mately corresponding to the direction of the adjacent mount- 
ains on the mainland. The slope outside the 100 fathom line 
along the southern coast is accentuated, but not so markedly 
so as farther north. The surface of the broad portion of the 
plateau is far from being uniform. Some of the islands rise 
over 2,000 feet above sea level, while the depths of the sea at 
their bases often reaches 600 fathoms. Southwest of San 
Diego about 35 miles there is the greatest depression in the 
plateau. Along the coast of Lower California the plateau 
narrows. How shallow portions of the plateau are, is shown 
by the fact that the 30 fathom line would include the larger 
of the Farralones islands lying 20 miles off the shore oppojiite 
the Golden Gate, while the 25 fathom line takes in the Coro- 
nados islands 12 miles off shore opposite San Diego. 
The charts show a large number of submarine valleys open- 
ing from landward down across this plateau reaching a depth 
of from 100 to 500 or more fathoms. Where the plateau is 
narrow, as on the northern coast, they cut a trench completely 
across it. Where the width is greater off the coast of south- 
ern California the vallej's open from the shore down, merely 
to the deeper portions of the plateau itself. In several in- 
stances the valleys come very close to the shore, as at La 
Jolla, Newport, Hueneme, Monterey, and on the coast of 
Humboldt county. A most remarkable fact about these val- 
leys is that they are generally nearl}^ or quite at right angles 
to the shore line, and consequently to the broad structural 
features of the country. Professor Lawson's view that they 
are structural depressions seems utterly untenable in the light 
of this as well as other facts. An interesting feature of the 
plateau, especially that portion above the 100 fathom line is 
its very even surface. Across this surface the deep transverse 
valleys have been trenched. The submarine contours follow 
that of the shore line to varying depths, corresponding very 
closely sometimes down to 300 fathoms. Not only does the 
submarine surface present a smoothness in most marked con- 
