100 



MARION EXPEDITION TO DAVIS STRAIT AND BAFFIN BAY 



tongue, oradiially freed of its upper part, finally acquires the reserve 

 buoyancy 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, f'ollowing the general I'ule for ice and water in contact, 

 melting proceeds fastest at the water line, the ])r()file of the glacier 

 fronts tending to bs deeply grooved at the surface of the fjord, 

 with an overlianging upper and a jutting underportion. The upi)er 

 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 disruption due 

 to the forward movement of the glacier. 



Form and Size of Bergs 



Icebergs in the northw^estern North Atlantic vary greatly in form ; 

 they may be pinnacled, domed, roofed, or ledged; but spired, min- 



The Blocky Precipitous-Sided Class of icebergs 



Figure 60. — Second only to the rounded and pinnacled class of bergs 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 bergs 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 bergs, or bergs clustered with icicles are rarely seen outside of 

 the school geographies. Their irregular shapes are not surprising 

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

 the many subsequent processes of disintegration that are constantly 

 wasting the berg away. Despite the many agencies which tend to 

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

 bergs several which bear a common resemblance. 



In this respect the irregular, donie-sha])ed bergs which constitute 

 the largest group are strikingly distinguished from the flat-topped 



