CLARK: ABYSSAL TEMPERATURES 415 



The temperatures between 1500 and 2000 fathoms correspond 

 closely with those below 2000 fathoms; but while south of the 

 Gulf of California the excess is the same for both levels, north 

 of that point the deficiency in the shallower water is approxi- 

 mately only one third of what it is in the deeper, excepting in 

 the Bering Sea, where it is half again as great. 



The series of temperatures between 1000 and 1500 fathoms 

 is interesting in showing an excess of warmth off the Chilean 

 coast (+0.40°) increasing to off northern South and Central 

 America (+0.66°), where we noted the maximum in the pre- 

 ceding series, and decreasing again off central Mexico (+0.25°), 

 as in the 1500-2000 fathom level. In the Gulf of California 

 there is, as before, a second, higher, maximum (4-1.40°). Off 

 southern California there is apparently a considerable excess, 

 but this is based on a single record which is very likely erroneous. 

 Except for this the deficiency increases from the region north 

 of the Gulf of California ( -0.04°) to the Gulf of Alaska ( -0.37°), 

 becoming nearly twice as great again ( — 0.69°) in the Bering Sea. 



The points of especial interest are the maximum off northern 

 South and Central America, and the uniformity between 45° 

 and 59° 19' N. lat., the latter contrasting with what we found 

 to be the case at the two preceding levels. 



Between 750 and 1000 fathoms the points of interest are: 

 (1) A well marked maximum (4-1.22°) off northern South and 

 Central America; (2) a relatively low excess (+0.50°) in the 

 Gulf of California, which is continued to 32° N.; and (3) an 

 excess, instead of a deficiency as everywhere below 1000 fathoms, 

 as far as 33° 42' N. 



Between 500 and 750 fathoms the chief excess is in the Galapa- 

 gos Islands ( + 1.30°) and in the Gulf of California ( + 1.10°). 

 There is a deficiency off Chile, and a progressively increasing 

 deficiency from 33° 42' N. to the Gulf of Alaska and the Bering 

 Sea. 



If we except for the moment the pocket-like Gulf of California, 

 which is comparable to the Red Sea or the Adriatic, the abyssal 

 temperatures along the west American coast are found to fall 

 into two classes, one capable of further subdivision, as follows: 



