1 92 1. No. II. 



THE STRANDFLAT AND ISOSTASY. 



31 



Fig. 12. Northwest shore of Reindeer Islands (Kjellman Islands), coast of Siberia. (August 20, 18931. 



level, and is covered by snow-drifts during the winter. This ice and snow 

 remain in greater or smaller patches on the beach, above high-tide level, 

 during the summer, or at least during the greater part of it (cf. Figs. 1 1 

 and 12). Along their edges, especially on their inner side, a very effective 

 erosion goes on during the melting season in the manner mentioned on p. 25. 

 As the dark shore cliff absorbs the light heat-rays, the melting will begin 

 very early at its base. All cracks, fissures, and pores in the rocks are kept 

 full of melting water, ready to freeze at the slightest frost, and will split 

 the rocks [cf. Nansen, 1920, 1921, Chap. VIIIj. 



As the masses of melting snow and ice, as well as the cold sea surface, 

 keep the air temperature near the freezing point of water, a slight fall of 

 temperature may be sufficient to cause frost. Alternations of thaw and 

 frost may therefore occur almost every day and night during a great part 

 of the year. 



Owing to its dark surface the rock will al)sorb the light heat-rays to 

 a much greater extent than the snow and ice surface. Every time the rock 

 is exposed to direct sun-shine it may, therefore, be heated to temperatures 

 much above the freezing point of water, although the air-temperature in 

 the shade is very low. The snow and ice, especially along the vertical 

 always dark rock-walls, will then be melted, and the fissures and cracks 

 of the rock kept full of liquid water. As soon as the direct sun-shine 

 disappears from the rock surface, this water will freeze at once. 



This process may be repeated several times during the twenty four 

 hours, and may begin very early in winter or spring, as soon as the sun 

 rises sufficiently high to have an appreciable effect. In not too northern 

 latitudes it may even occur, more or less, during the whole winter. In 

 polar regions I have observed drops of liquid water being formed on the 

 surface of white ice cliffs in this manner when the air-temperature was 

 below — IS*' C 



In regions where the sea is covered by ice during the winter, it is 

 also of importance in this respect that, during late winter and spring, the 

 atmosphere is generally very clear, and there may be continual sun-shine 



