SCIENTIFIC RESULTS 



101 



precijiitons-sided type. The glaciers of Disko Bay and Northeast 

 Bay discharge most of the picturesque forms, while northward in 

 Melville Bay, where the ice sheet itself is thrust directly out into the 

 sea, many of the square, blocky icebergs are produced. The marked 

 difference in form, therefore, may be largely attributed to the type 

 of the coastal land underlying the margin of the inland ice. Plateau- 

 like bergs may maintain their equilibrium for a year or longer, for 

 such have been sighted even off Newfoundland with the original 

 dust and wind-blown sand of Greenland coloring their to]5s. 



But the triangular, dome-shaped berg and the straight-sided 

 type enter the Atlantic as bulky, nuissive bodies, worked upon hence- 

 forth by the various agencies of destruction. Bergs in the far north, 

 with few exce]itions, maintain their original outlines but after in- 



The Dome-Shaped Class of Icebergs 



FiGfEE 61. — A Davis Strait bers observed by the Marion expedition tlie summer of 

 1028. Its domed and rounded sliape is chnraeteristic of the hirgest class of bergs 

 to be found in the nortliwes.tern North Atlantic. Its proportions of air-expose<l 

 body to be submerged are 1:5 to 1 : 4. (OfBcial photograph, Marion expedition.) 



vading the warm oceanic waters of the Atlantic they melt so rapidly 

 that tiiev change appearance often. The boxlike berg is first washed 

 and melted around the water line, and this continual undercutting 

 of the ])erpendicular sides results in a corresponding breaking away 

 of the prominences above. After a time the unequal detacliments 

 cause the ice to lose e(iuilibrium and the roof tilts, forming a 

 V-shaped berg. The absence of the square, upright types after mid 

 season at the Atlantic terminus is noteworthy. 



The well-known girdling incision at the water line is a common 

 characteristic from which few bergs are free. Overhanging ledges 

 strained beyond the structural strength of the ice detach, causing 

 the bei-g to roll, so that it floats in a new plane, leaving the old 

 water line clearly visible for miles. We have seen bergs off' the 

 Ijrand Bank with as many as three or four old water lines marked 



