1 92 1. No. 1 1. 



THE STRAXDFLAT AND ISOSTASY 



Fig. 129. From the sandstone area in the central part of Bear Island. lo the right where 



the ground is darker is seen a part of a small isolated ridge of Spirifer limestone north of 



Alfred Mountain. (Photograph by O. Holtedahl 19 181. 



great importance mainly by washing away the debris of the shore erosion, 

 and also by wearing down the outer parts of the plain. 



We can at present observe this denudation process going on along 

 the shores of Bear Island, wliere it has formed the vertical shore cliffs, 

 with many small accumulations of ice and snow lying on the beach at their 

 foot during a great part of the summer (see Fig. 11). 



That the wave erosion also has much direct effect along this weather- 

 l:)eaten coast is demonstrated by the many caves formed in tlie present-day 

 shore-line [see Xansen, 1920, PI. III]. I have observed such caves in 

 South Harbour ("Sorhavn", Fig. 124), in Walrus Harbour ("Hvalross- 

 havn", Fig. 124), and in Norwegian Harbour ("Xorske-havn", Fig. 124). 

 Holtedahl has found deep caves penetrating far inland on the south-west 

 coast of the island. The caves are generally formed along lines of frac- 

 ture in the rock. 



As I have pointed out before (p. 144) the disintegration by frost is, 

 in my opinion, of much importance also for the formation of caves in this 

 cold climate. Where the average temperature of the rock is below freezing 

 point of water, there will easily be alternate thaw and frost according as 

 the rock surface be washed by the sea or left dry. As far as I have seen, 

 it is on the whole striking to what a small extent the walls of these caves 

 exhibit traces of direct wa\e erosion, /. c. forms rounded by the waves. 

 The surfaces are generally rough like that of rock exposed to disinte- 

 gration by frost, and the edges are only to some small extent water-worn. 



Where there are limestones or dolomites, or where there are fractures 

 in the rock filled with limestone, the lime may be dissolved by the sea- 

 water, or also by fresh water, provided that the low temperature of the 

 rock does not prevent liquid water from percolating through the fractures 



