284 



University of California Publications. 



[Geology 



writer attempted to construct an isothermal chart for the depth 

 of 700 Fm. in order to follow further this cold undercurrent. 

 The number of temperature observations for this or greater 

 depths is few, and therefore not much reliance can be placed 

 in the results. The isotherms as drawn for the 700 Fm. level 

 show a narrow loop extending still farther to the southeast than 

 the loop in PI. 37. It would thus seem from the evidence now 

 at hand that the cold water at the bottom of the south central 

 portion of the North Pacific is accounted for by a branch of the 

 Kamchatka current underrunning the upper portion of the 

 warm Japan stream and slowly sinking to the bed of the ocean. 



In the provisional isothermal chart drawn for the depth of 

 700 Fm. a second narrow loop of the isotherms, starting farther 

 to the east of the Japan Islands, runs southeast toward the 

 Hawaiian Islands. This would account for the presence of 

 water below 35° F. that occurs to the northward of these islands 

 at the depth of 2,500 Fm. 



The study of the areas of cold water at the bottom of the 

 central portion of the North Pacific does not therefore in any 

 way contradict the hypothesis used for the cold water belt along 

 the west coast of the United States. In the northwest due to 

 the opening into Bering Sea between Kamchatka and the Aleu- 

 tian Islands, a southward flowing cold current disturbs the 

 otherwise great uniform clockwise drift of the North Pacific. 

 In the north central and northeastern portions of the ocean 

 there are no cold currents from Bering Sea to interrupt the ac- 

 quirement of a uniform direction of drift to great depths. 



The possibility of water at a great depth acquiring a slow 

 movement or drift from the action of surface winds has been 

 frequently discussed. A recent writer* thinks that the entire 

 body of water occupying the equatorial regions has a westerly 

 motion due to the action of the trade winds. In the northern 

 parts of the Pacific in the region of the prevailing westerlies, 

 contrary currents are frequently reported more or less in har- 

 mony with variations in the winds. But as the prevailing 

 westerlies have existed for untold ages, there has been ample 

 * Page, James. National Geographic Magazine, 1902, pp. 135-142. 



