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University of California Publications. [Geology 



contour according' to these late soundings. The distribution 

 of these areas of cold water on the ocean bottom is closely 

 related to the question of the source of the cold water 

 along the west coast of the United States. Of primary in- 

 terest is the larger area extending from near Alaska south- 

 ward far beyond Point Conception. The part of this mass 

 of cold water lying north of Lat. 50° is bounded on the 

 north and east by the contour line of 2,000 fathoms (nearly 

 4,000 M.). The western extension of this mass of cold and pre- 

 sumably heavy water lies just on the edge or slope of a sub- 

 marine valley that runs down to a depth of more than 3,000 

 fathoms (6,000 M. ). If the distribution of cold water in the 

 ocean depths depends on convection as is frequently claimed, 

 why does not the cold water settle into this deep valley? This 

 might be answered by supposing greater density for the water 

 in the greater depths. A discussion of the varying salinity on 

 tlie bottom of the ocean in this region is at present impossible 

 from lack of accurate data. The uniform upper level of this 

 mass of cold bottom water is an interesting point when the North 

 Pacific Pilot Charts of this region are examined. In this great 

 bight of the Alaskan coast there is represented an ocean eddy 

 turning contraclockwise for three-fourths of the year and being 

 reversed in direction during the winter months. Is it possible 

 that this eddy maintains a mass of cold water at the bottom at 

 a constant level? The idea of a casual relation here is so seduc- 

 tive that the writer feels compelled, in fairness, to quote a para- 

 graph from the Pilot Chart: — "After a careful consideration 

 of the reports of vessels cruising near the Aleutian Islands and 

 in the Bering Sea, the Hydrographic Office warns mariners 

 against placing too much reliance upon current predictions in 

 that portion of the North Pacific." The warning is probably 

 intended to apply -to regions farther to the westward, but should 

 be considered for this region as well. In connection with the 

 question of the existence of this Alaska eddy, it is to be remarked 

 that the isotherm of 55° bends to westward just south of Alaska 

 in a way to confirm the existence of such an eddy. ( See PL 32. ) 

 Setting aside theories and keeping in mind the thought of the 



