we may then consider that as a result of these processes there is created the distribution of tem- 

 perature and salinity which is observed in the surface layers of the Arctic Basin. 



From an examination of the vertical distribution of velocities in the upper layers of the Arctic 

 Basin (from to 400 m) we see that the velocity, let us say, between levels 75 and 100 m, although 

 also in the direction towards the straits between Spitzbergen and Greenland, is considerably less 

 than the speed of the topmost layers. From this it follows that the water which lies at a depth of 

 75 to 100 m is "older" than that of the upper layers. And since, other conditions being equal, more 

 ice is formed during the winter, the greater is the depth of the vertical circulation, it follows that 

 these layers will retain traces of the most intense ice formation for a very long time. 



As we have seen, there are regions in the Arctic Basin where the floating ice during the 

 course of the winter is constantly carried away from the shore and from the fast ice. In these re- 

 gions there occurs a more intense ice formation, and as a result, a more intense salinification of 

 surface strata. There are also other factors in the Arctic Basin (besides the coastal drainage and 

 decompressive currents and winds) which have an influence on freshening and salinification of sur- 

 face strata. Worthy of attention in this respect are the phenomena connected with the concept of 

 limit to the thickness of many-year-old ice. Actually, if ice is carried by currents or winds into 

 regions where its thickness is less than the limit thickness of ice of this region, here there will 

 occur a supplementary ice formation and consequently a salinification. Conversely, if ice is 

 carried into a region where its thickness is greater than the limit thickness, melting will commence, 

 and as a result, a freshening of surface strata. Thus, the surface arctic water has its main origin 

 not only in the mixing of river water with Atlantic water, but is also caused by other extremely 

 complex processes, the most important of which is the melting of ice segments which jut out deeply 

 from under the lower surface of the ice fields. Here we may only emphasize that a level upper 

 surface of pack ice fields (absence of hummocks or smoothing over of them) compels us to assume 

 that the lower surface of the pack fields is also levelled by the washing action of the water. 



Upon analyzing the distribution of salinity observed by the expedition in 1935 in the Kara Sea, 

 I was struck by the following circumstance. At the numerous observation points in the northern 

 part of this sea the salinity of the cold surface layers was everywhere lower than, for example, in 

 the oceanographic sections located more to the south, and in particular, along the section which 

 traversed the whole of the Kara Sea at about 79° north. 



It turned out that a peculiar belt of surface water of comparatively high salinity was located 

 between Franz Joseph Land and the central part of Sevemaya Zemlya. I explain the origin of this 

 belt of increased salinity in the following way: 



1. In the region of increased salinity, the deep Atlantic water (flowing here as a deep current 

 from the central arctic) rises to the surface due to the decrease In depth of the sea, and mixing 

 with the surface water, increases its salinity. 



2. The region of increased salinity is located at approximately the transition point from the 

 great ocean depths to the lesser depths of the continental shelf. On this account, here exactly 

 should be observed great tidal amplitudes, great speeds of tidal currents, and consequently, in- 

 creased lateral mixing. 



3. In the region of increased salinity the ice during the winter season is constantly broken 

 off and carried away to the north by winds . On account of this , intensive ice formation occurs 

 here entailing the salinification of the surface layers. 



409 



