104 MARION^ EXPEDITION TO DAVIS STRAIT AND BAFFIN" BAY 



ceedingly dangerous to a ship passing close by. The British steamer 

 Ness7nore was severely damaged by such a projection, and it is com- 

 mon report that a similar obstruction caused the tragic loss of the 

 White Star Liner Titanic. 



The bergs which penetrate far south in summer, or deeply into 

 the Gulf Stream, often assume a completely water-washed, polished 

 form, like a beach-worn stone. (See fig. 74. p. 114. ) No sharp prom- 

 inences are visible anywhere and such bergs are usually low. hence 

 very difficult to detect. The most striking form is given to icebergs 

 entering the North Atlantic by washing. The continual surging of 

 the waves and swell back and forth finds the zone of greatest weak- 

 ness developing a central bore and later a deep, wide valley. Such 

 bergs are a familiar sight south of Newfoundland and are called by 

 various names : "' Valley," '" dry-dock," " winged," " bicuspid," " sad- 

 dle-back." and '' double-horned." (See fig. 63, p. 103.) 



Steamers often report two bergs close together when correctly 

 speaking, it is simply one old eroded iceberg whose valley bottom is 

 submerged beneath the sea. Blowholes and reentrant caves are not 

 uncommon features through wdiich the swell sometimes spouts 

 hundreds of feet in the air. The valley berg, fragile in its last 

 stages, consists of thin walls, that eventually break off, and in periods 

 of smooth weather beautiful, curved, and slender "' swan's necks " 

 are carved by the sea. High arches are on rare occasions sighted. 

 In most instances they represent the washing of the waves that 

 started with a small cave and wore it larger and larger, but in some 

 cases the}^ may be relics of caves formed in glacier fronts by the 

 escape of glacial thaw water. 



The icebergs are largest in the vicinity of the fjords soon after 

 their birth and diminish in size the farther they are carried into the 

 Atlantic. The highest berg of a group of 87 measured bv Drvgalski 

 (1895, p. 401), in Northeast Bay was 447 feet. Hellaiid (1876, p. 

 106), measured bergs to a height of 292 feet and Steenstrup (1883, 

 p. 96), 249 feet. Again Helland measured 8 bergs in the mouth 

 of Jacobshavn fjord, 142, 145, 146, 181, 198, 201, 343, and 356 feet, 

 the largest of which contained 718,000,000 cubic feet (17,000,000 

 tons), with 230 feet as a common lieight for a large iceberg. Dry- 

 galski measured a group of 70 bergs assorted as follows: Four were 

 over 325 feet high, 14 were between 230 and 325 feet, 25 were between 

 160 and 230 feet, and 27 were less than 160 feet. The figures for 

 bergs in the vicinity of the large glaciers are as follows: 



Great Karajak : 250, 253, 207, 211, 250, 241 feet. Height of glacier 

 front, 160 to 330 feet. The average height of bergs from Great 

 Karajak is 180 to 250 feet. 



Itividliarsuk : 194, 192, 214, 224, 230, 230, 95, 125 feet. Height of 

 glacier front, 227 to 260 feet. 



Jacobshavn : 69, 105, 135, 214, 330, 336, 447 feet. Height of glacier 

 front, 277 feet. 



The foregoing shows that Jacobshavn calves the highest ice- 

 bergs in the north with Great Karajak following a close second. 

 The icebergs of east Greenland are apparently not so high as those 

 of the west coast, as Amdrup (1900, p. 243), estimates the largest of 

 these as 160 to 215 feet in height and about 3.280 feet in length. The 

 loftiest berg observed by the international ice patrol south of New- 



