CLARK: ABYSSAL TEMPERATURES 417 



this coast is supplied, as I have already suggested (basing my 

 conclusions on biological data) may be the case, from the Antarc- 

 tic regions through the medium of an offshore abyssal current 

 which is drawn shoreward by the upwelling off southern Cali- 

 fornia and in the Gulf of Alaska. But the observations on the 

 bottom temperatures between California and the Hawaiian 

 Islands seem to cast serious doubt on the existence of such a 

 current. The biological data are adequate, and point to a 

 definite conclusion; but since animals readily pass from water 

 of a certain origin to water of quite a different origin, if the two 

 have the same biological coefficient (temperature, food value, 

 salinity, and silt in approximately the same relative proportions) , 

 biological data are always unreliable. The physical data are 

 far from exact, and we have no chemical data. Thus the true 

 explanation of this phenomenon, if it be real and not merely the 

 result of inaccurate thermometer readings, must be left to the 

 future. 



In the Bering Sea there are 103 temperature observations in 

 water of over 500 fathoms in depth which may be regarded as 

 approximately accurate. 



Between 500 and 750 fathoms the average temperature for 

 the Bering Sea as a whole is —1.71° below that of the entire 

 ocean. There is an appreciable, though small, difference be- 

 tween the regions east and west of the 180th meridian, the former 

 being 0.63° warmer than the latter. But below 750 fathoms 

 there is no appreciable difference east and west of 180° — only 

 0.02° between 750 and 1000 fathoms, with the lower reading in 

 the east, and 0.01° from 1500 to the deepest readings, with the 

 lower reading in the west. 



Between 750 and 1000 fathoms we find an average tempera- 

 ture — 0.91° below that of the ocean as a whole at that depth; 

 between 1000 and 1500 an average of —0.69°; between 1500 

 and 2000 an average of —0.23°; and below 2000 an average of 

 — 0.15°. This is in interesting contrast to the conditions in the 

 Gulf of Alaska where the temperature of the water is approxi- 

 mately the same as in the Bering Sea as a whole between 500 

 and 1000 fathoms, less cold between 1000 and 2000 fathoms, 

 more cold again below 2000 fathoms. 



