Vol. 4] 



Hohoay.—Cold Water Belt. 



281 



level upper Limit of the cold bottom water as mapped by Murray 

 for the region south of Alaska, let us examine its great southward 

 extension. 



From oft' Vancouver Island to San Francisco it lias risen 

 above the 2,000 Fm. (4,000 M.) contour and lies upon the conti- 

 nental slope of the ocean bottom — again in defiance of gravity 

 unless tbere is postulated a peculiar arrangement of salinity in 

 the lower depths. 



HYPOTHESIS ACCOUNTING FOR COLD WATER BELT. 



To explain this apparently abnormal position of the cold 

 water, let us suppose, as a working hypothesis, that the direction 

 of ocean drift in the northeastern parts of the North Pacific is 

 not merely true for the surface, but that it holds throughout 

 the entire extent as far as the ocean bottom. In winter the cold 

 surface water to the south of the Aleutian Islands would sink 

 and at the same time be carried slowly toward the eastward. 

 It would thus be carried over the western portion of the Maury 

 Deep of PL 36 and would finally rest on the continental slope. 

 In the Alaska Bight it is conceivable that the eddy would give 

 a constant upper level to this mass of water. To the southward 

 along the coast of Vancouver to San Francisco, the upper drift 

 (except very close inshore) is toward the east and south If 

 this drift extends to the ocean bottom, the cold bottom water 

 would be driven up the continental slope, thus accounting for 

 the belt of cold coast water. Again it will be remembered that 

 the coldest coast water was found from the vicinity of Cape 

 Blanco southward to Cape Mendocino. In PI. 36 the contours 

 of 1.000, 2,000, and 3,000 meters make a shoreward bend slightly 

 north of this latitude. That is, a great submarine valley heads 

 just under Cape Blanco and opens broadly out to the northward 

 and westward. The bottom drift on our working hypothesis 

 would thus be delivered most strongly against the coast in the 

 vicinity of Cape Blanco and carried southward by the general 

 drift. 



