(which I term "drift currents" as distinguished from wind-caused currents), the light surface 

 water due to deflective force of earth's rotation is forced towards the right-hand shores (looking 

 down the current), sea level is raised in the direction of the shore and the direction of currents 

 along the vertical is almost unchanged. 



LITERATURE: 57, 62, 77. 



Section 130. Movement of Ice in Sea Currents 



The movement of ice floes which have the largest part of their volume submerged in the 

 water, in the absence of wind, is determined by the direction and speed of the currents of the given 

 region of the sea and has the following peculiarities: 



1. Individual ice formations (icebergs, floebergs) sometimes have considerable draft. Obvi- 

 ously, such an ice formation will move according to the resultant movement of the water layers in 

 which it is submerged. 



2. The circulation of water masses includes both the horizontal and the vertical movement of 

 water. It is natural that the ice, participating as it does in only the horizontal movements, in cer- 

 tain cases will move separately from the movement of the surface water. 



3. The areas occupied by ice, as well as the horizontal dimensions of individual floes, 

 undergo seasonal changes and long-term changes. Therefore, the ice movement in rivers may 

 experience interruptions (ice formation, blocking, etc.), depending on local conditions. 



As a general rule, the speed of sea currents gradually decreases with depth. Therefore, the 

 greater the draft of the ice, the slower its movement by comparison with movement of surface 

 water. Thus the icebergs and floebergs which sit deep in the water usually move slower than the 

 surrounding fragments of the broken ice fields and from the side it sometimes seems that they are 

 completely without movement, as if they were sitting on a shoal. It is due to this that surf may 

 often be seen at the ends of some icebergs and this creates the impression of movement. Since in 

 some few cases the deep currents may be distinctly different from the surface currents in both 

 speed and direction, and may even be in an opposite direction, icebergs and floebergs may some- 

 times be observed drifting across or even against the current. 



Ice formations of large horizontal dimensions may drift into an area where there are two sur- 

 face currents which are different in speed and direction. In such cases the ice acquires a rotary 

 movement along with the forward movement. This occurrance is especially typical in compara- 

 tively narrow straits and where many eddies and whirlpools are formed. Rotating ice is constantly 

 observed in the Datski Straits, Khinlopen Straits, Straits of Franz Joseph Land, neck of the White 

 Sea, and in other straits. We have seen, in particular, that the rotation of ice by sea currents has 

 been proven for the ice of the Chuckchee Sea. 



The fact that the circulation of water masses includes both horizontal and vertical shifting of 

 water while the ice can move only in a horizontal direction results in an accumulation of ice wher- 

 ever there are points or lines of junction of sea currents in which the surface water layers are de- 

 scending. Conversely in points or lines of divergence of sea currents we observe a thinning of sea 

 ice and formation of polynyas. This phenomenon may be permanent, periodic, or temporary. 



Since every movement in the northern hemisphere deviates to the right and in the southern 

 hemisphere to the left, due to Coriolis force, every current which washes a right-hand coast in the 



349 



