282 



University of California Publications. 



[Geology 



The effect of the smaller submarine valleys near the coast 

 has already been discussed by Davidson.* Speaking of those 

 near Cape Mendocino he says: "They carry in the colder 

 waters coming from the north and outside of the influence of the 

 close inshore eddy current setting to the northward." 



The writer fully agrees with this statement, but in the light 

 of the additional data discussed in this paper, he considers the 

 action of these valleys as but part of a general motion of the 

 deeper waters which affects the entire coast from San Francisco 

 to Vancouver Island. 



Another instance where local temperatures seem to be influ- 

 enced by submarine valleys is found on Cordell Bank about 50 

 miles west-northwest from San Francisco and directly west of 

 Point Reyes. The 100 Fm. contour shows a valley opening to 

 the northward and heading just east of the Cordell Bank. 

 From June 12 to 17, 1873, Davidsonf reports the mean water 

 temperature at 8 a.m. as only 49°. If the cold bottom water in 

 the deeper ocean has any motion or drift, it is not difficult to 

 recognize the fact that the submarine valley to the northward 

 might lead it to the surface in the vicinity of Cordell Bank. 



A second point in favor of the theory of great depth to the 

 prevailing drift in the northeastern part of the North Pacific is 

 found in the shape of the areas of cold bottom water and in 

 their relation to the surface drift. The main area on the west 

 coast of North America has a longitudinal extension that agrees 

 with the prevailing surface drift. Tracing this area of cold 

 bottom water southward to Lat. 30°, it is seen to bend to the 

 southwestward as do the surface currents. The question also 

 arises as to the reason for a termination of the cold water at this 

 locality. It is certainly not the insolation received in the torrid 

 zone, for this penetrates but a short distance below the surface 

 of the ocean. Moreover, in the middle of the North Pacific ex- 

 tending across the equator into the southern hemisphere is one 

 of the largest areas of water below 35° on the ocean bottom. A 

 ready explanation for the termination of the cold bottom water 



* Davidson, Geo. The Submerged Valleys of the Coast of California, 

 etc. Pro. Calif. Acad. Sci., Geol. Vol. I, p. 99. 

 t Davidson, Geo. Pacific Coast Pilot, p. 236. 



