THE TITANIC— 50 YEARS LATER 



Once the icebergs are waterborne the long drift to the shipping 

 lanes is underway. First the icebergs drift northward with the West 

 Greenland Current into the Baffin Bay Basin, where they may spend 

 their first winter frozen in the ice. Thence, drifting westward across 

 Baffin Bay, they commence their southerly movement under the 

 influence of the Labrador Current. Many bergs that survive the 

 first winter ground and break up along the treacherous Labrador 

 Coast. The surviving icebergs may spend their second winter frozen 

 in the Davis Strait region and from there, as soon as the pack breaks 

 up in the spring, the remaining bergs drift southward with the 

 Labrador Current toward the Grand Banks. 



In an average year, about 400 icebergs drift below the 48th paral- 

 lel with about 35 continuing their southerly drift past the Tail of the 

 Banks to menace the trans-Atlantic shipping lanes. Yearly vari- 

 ation is great. During the peak ice year of 1929 an estimated 1,352 

 icebergs drifted southward of the 48th parallel. Yet in 1958 only 

 one iceberg was observed. However, the following year, 1959, there 

 were 693 bergs in evidence. This variation has not been fully ex- 

 plained but is probably related to climatological conditions over the 

 entire iceberg-producing area and the distribution of pack ice in the 

 Davis Strait. Icebergs may be encountered any month of the year, 

 but in the Grand Banks area over 90 percent of them are encountered 

 from March thru July, which constitutes the usual ice season, with 

 the heaviest concentration from mid-April to mid-May. 



icebreaker techniques, convoying, and towing in ice. A comprehensive 

 glossary of ice terms is also included in this reference. 



Natural deterioration commences as soon as newly-calved ice- 

 bergs are waterborne. Melting processes are always at work. Al- 

 though nearly dormant during the winter months, they speed up as 

 the temperatures rise in the spring and reach an accelerated pace 

 when the bergs drift farther southward into the warmer waters off 

 the Tail of the Banks. In areas where the air temperature is well 

 above the water temperature bergs will melt faster above the water, 

 retaining their stability, and, as the bulk decreases, gradually rise 

 out of the water, leaving tell-tale encircling rings of former waterlines. 

 If the water temperature is high enough to melt the underwater por- 

 tion faster, bergs become unstable and frequently oscillate to new 

 positions of equilibrium, thereby creating new strains on protruding 

 portions that may cause them to calf off, thus inducing another shift 

 in the equilibrium of the berg. Sea water is the principle factor in 

 the natural disintegration of an iceberg. Therefore, the area of a 

 berg near the waterline is subject to the greatest melting, or actual 

 erosion, by the continuous wave action sloshing warmer surface 

 waters against the waterline of the berg, eating into cracks and crev- 

 ices, and undercutting the sides, thus creating new protrusions, new 

 strains, and renewed calfing. Melting of the underwater portion also 

 releases the innumerable tiny pockets of entrapped air which bubble 

 to the surface in an audible effervescent effect. Throughout their 



The density of icebergs may vary slightly as galciers are com- 

 posed of compacted snow. In the upper layers of the Greenland Ice 

 Cap the entrapped air content may be as great as 50 percent of the 

 volume. But, by the time the ice has traveled along the glacier to 

 the sea, the great pressure has reduced the air content by volume to 

 somewhere between 7 and 15 percent and the density is about 0.899 

 as compared to a density of 0.917 for fresh water ice. The average 

 iceberg floating in sea water with a density of 1.028 will have about 

 87.5 percent of its mass below the surface of the water; therefore, 

 the portion above water represents approximately one-eighth of the 

 bulk of an iceberg. Arctic icebergs may weigh as much as about 

 1,500,000 tons, but icebergs found off the Grand Banks are seldom 

 larger than about 150,000 tons. Berg ice in solid condition, is very 

 hard and melts slower than artificially made ice, despite the general 

 appearance of softness. Icebergs are of a peculiar opaque flat white 

 color resembling snow, often with soft iridescent hues of green and 

 blue. The snowy appearance is caused by surface weathering and the 

 affect of the sun's rays releasing innumerable air bubbles. Bergs may 

 be striped with blue or green veins of hard transparent ice which stand 

 out strikingly against the porous white background. Brown and 

 yellow patches, probably due to some form of planktonic life, may 

 appear on them. Rock and earth remnants of old glacial moraines 

 dart through the bergs in ribbons of brown, gray, and black. 



An excellent and convenient reference on the formation, growth, 

 movement, and dissolution of ice in general can be found in Chapter 

 1 of H. 0. Pub. No. 47, " Saihng Directions for the Northern 

 USSR." This reference also discusses the hazards involved in 

 handling, maneuvering, and navigating a vessel in ice, as well as 



Removing Nansen Bottle. 



37 



