100 



MARION EXPEDITION TO DAVIS STRAIT AND BAFFIN BAY 



toiioiie, o'l'adiially freed of its upper |)art. tinally acquires the reserve 

 buoj^ancy necessary to initiate calving. 



It seems most likely that the two principal factors responsible] 

 for calving can be defined as disintegrative processes due to (1) the 

 static position of the glacier end, and to (2) the dynamic form of 

 the glacier. Following the general lule for ice and water in contact, 

 melting proceeds fastest at the water line, the profile of the glacier 

 fronts tending to 1)? deeply grooved at the surface of the fjord, 

 with an overlianging upper and a jutting underportion. The upper 

 ledge is broken back solely by its own weight, while the underwater 

 ledge is continually broken away by its own buoyancy. Superim- 

 posed on this type of wastage and of first importance in the case of 

 the very active glaciers is the continu.al fraction and disru]:)tion due 

 to the forward movement of the alacier. 



Foior AND Size of Bergs 



Icebergs in the northwestern North Atlantic vary greatly in form;i 

 they nuiy be ]iinnacled, domed, roofed, or ledged : but si)ired. min- 



The Blocky Precipitous-Sided Class of Icebergs 



Figure 60. — Second only to the roundt'd and pinnacled class of bert,'s is the blocky, 

 steep-sided type which often reach the waters south of Newfoundland in the same 

 plane of equilibrium that they left the glacier. This class of beriis is calved mostly 

 from points where the topography permits the ice cap to directly face the sea. An 

 example of such a locality is Nansen Glacier in Melville Bay. (Official photograph, 

 international ice patrol.) 



areted l)!?igs. or bergs clustered Avith icicles are rarely seen outside of 

 the school geogra])hies. Their irreguhir sha])es are not surprising 

 wdien one considers how calving from the glacier takes place, and 

 the many subsetjuent })rocesses of disintegration that are constantly 

 wasting the berg away. I)es])ite the many agencies which tend to 

 destroy uniformity, there are however, in any unassorted run of 

 bergs several which bear a common resemblance. 



Tn this res])ect the irregidar. douie-shaped bergs wliich constitute 

 the largest grouj) are strikingly distinguished from the thit-to])i)e(l 



