foreign elements are washed away from the snow and ice into the deeper cavities of the water pud- 

 dles, the raised parts of the ice become less saline due to washing by the thaw water of the brine 

 from the salt cells, and the hummock contours become rounded. 



3. After the individual deep spots in the snow puddle have melted througji completely the snow 

 water runs off under the ice with subsequent ice formation underneath the existing ice. The newly- 

 formed ice eventually rises to the surface with the melting of old ice above. This phase concludes 

 the weakening of sea ice. 



4. The first phase of ice destruction is the breaking-up, under the influence of external 

 forces, of the ice fields into more or less large sections along the lines of least resistance. The 

 first movements of the ice cause the cracks to be made larger due to the hummocking of the con- 

 tiguous parts. In the process of hummocking the individual floes are not fused into a single piece 

 due to the fact that their temperature is high by this time. With the increase in quantity and size of 

 the cracks the amplitude of movement of the ice is progressively increased. 



5. The second phase of destruction is the rounding of the broken-up formations, the increase 

 in size of the water spaces which form a belt around the individual ice chunks, and the formation of 

 ice cornices and shoved -under floes, or posdovy. During this stage there is much movement of the 

 ice back and forth. The last ice ( pripai) ceases to exist as such and changes over to floating ice 

 floes. 



6. The next phase of destruction is the gradual decrease in vertical and horizontal dimensions 

 of floes. There occurs simultaneously a decrease in total ice area due to the collisions of the 

 separate fields and floes with each other, and due to the formation of hummocks. 



7. In the open sea, in the course of destruction of ice, not only are the dimensions of indi- 

 vidual floes decreased but also the total ice coverage. In this connection the washing action of the 

 waves becomes effective. The recessing along the water-line becomes greater and greater, and the 

 small floes finally acquire the very characteristic form of "ice lilies" and "ice ducks. " 



8. Under regular conditions of melting, the hummocked ice fields are gradually changed into 

 smooth fields. Thus the thickness of the fields becomes less and less, and before disappearing 

 completely, the ice becomes very similar to young "rind" ice, or nilas. Such a characteristic pro- 

 cess was carefully traced in the spring of 1942 by the air-reconnaissance missions of Kotov and 

 Morozov in the White Sea. 



9. The final phase of destruction is the disintegration of the ice into separate pieces; e. g. , 

 ice crystals or rounded ice globules of uniform texture and the remains of the condensed cores of 

 the hummocks. 



In order to make possible comparisons in the practical usage of information on the degree of 

 destruction of sea ice by thawing in spring and summer seasons, the following point scale has been 

 worked out by Somov: 



1 point - Complete absence of external signs of destruction. Breaks in the ice are 

 sharp. Ice surface is white. 



2 points - Small quantity of snow puddles; no cracks or drain holes present. If the 

 ice is in such small fragments that snow-puddles cannot form, the very 



296 



