2 CLARK: CIRCULATION OF ABYSSAL WATER OF OCEANS 



southward, along the eastern, northern and northwestern mar- 

 gins of these basins. At every point in their course these currents 

 give off water from their seaward (left) side which falls into the 

 abysses and forms the strictly abyssal water; on account of the 

 effect of the rotation of the earth this process is carried on far 

 more actively in the southern than in the northern hemisphere. 

 In the northern hemisphere the rotation of the earth; instead of 

 inducing the flow of water from the borders of these currents into 

 the abysses, tends to cause the currents to hug the coast and, by 

 rendering them more compact, to prevent the diffusion of their 

 water and hence to maintain their motion and to preserve them 

 as currents. Also it operates to bring their upper levels near 

 the surface so that, wherever a powerful surface current flowing 

 diagonally away from the shore causes the formation of a vacuum, 

 as it were, between itself and the coast, the water of these periph- 

 eral currents, composed of water of the strictlj" abyssal type, 

 and ultimately of antarctic origin, immediately rises to the 

 surface. This occurs off northwestern Africa and off southern 

 California, and again off the Kurile Islands and off the New 

 England coast from Cape Cod northward; on the New England 

 coast, however, the identity of the antarctic water is more or less 

 concealed by mixture with water of low salinity coming from the 

 north. 



In the pocket-like Gulf of Alaska the rotation of the earth 

 causes the water of the antarctic current to pile up, and to rise 

 nearly, in the winter possibly in some places quite, to the sur- 

 face. Over the surface of this cold antarctic water flows the wind- 

 impelled drift from the Kuro-Siwo, which divides, part of it 

 skirting the northern part of the Gulf of Alaska, and part flow- 

 ing southward down the coast. The water of the Kuro-Siwo 

 drift and the antarctic water are of the same salinity, and there- 

 fore they mix readily. Hence the southern derivative from the 

 Kuro-Siwo drift, the so-called California current, as it flows 

 southward dissolves into itself the cold water of the antarctic 

 stream immediately beneath it, presenting the curious phenom- 

 enon of a current flowing southward, yet at the same time 

 becoming colder and colder. 



