Editor’s note: we are publishing this article on the occasion of the 100th anniversary of the sinking of the RMS Titanic on April 15, 1912
Vol. CVI, No. 17, April 27, 1912
An iceberg is a fragment of a glacier. Inch by inch the huge river of ice which we call a glacier creeps toward the sea, and here its projecting end is broken off by the action of the waves. "Calving" is the technical name which has been given to this process of breaking bergs from glaciers. It is a process that occurs all the year around, but more frequently in summer than in winter, a process, moreover, that sets adrift thousands of huge ice masses during the course of a year.
Icebergs were a known hazard in the North Atlantic. Here is a map from 1912 showing where they were likely to come from and where the Titanic sank on April 15, 1912. Credit: Scientific American, April 27, 1912
The icebergs that find their way into the paths of transatlantic liners come down from the coast of Greenland; for the interior of Greenland is a huge ice sheet fringed by mountains and promontories. Deer fiords reach far into the inland ice, terminated only by the sheer walls of giant glaciers. Sometimes, however, the ice slides down in broad expanses close to the margin of the sea.
In the vicinity of the great Bank of Newfoundland icebergs appear in greatest numbers- in other words, athwart the transatlantic oceanic steamer routes. According to data collected by the United States Hydrographic Office, to which we are indebted for most of the information that appears in this article, icebergs have been seen in April, May, and June as far south as the thirty-ninth degree of latitude and as far east as longitude 38 degrees 30 minutes west of Greenwich. Indeed, floating ice may be encountered anywhere in the North Atlantic Ocean north of the fortieth degree of latitude at any season of the year.
How Icebergs Drift Southward.
It is the Labrador current that carries an iceberg southward. But ere it reaches the high seas, the berg may be subjected to many mishaps. It may ground in the Arctic basin; it may be stranded on the shores of Labrador and break up; it may disintegrate entirely. The numerous islands, bays, headlands, shoals, and reefs that constitute the coast of Labrador mercifully obstruct the passage of many icebergs and prevent them from reaching the waters of the North Atlantic.
Bergs, when first liberated on the west Greenland shore, are out of the strongest sweep of the southerly current, and they may take some months to find their way out of Davis Strait, while again others may at once drift into the current and move unobstructed until demolished in the Gulf Stream.
Little is known of the Labrador current, beyond the fact that it skirts the coast of Baffin Land and Labrador; that its usual rate of motion is from 10 to 36 miles a day; that its breadth and depth are uncertain; and that it occasionally ceases altogether. The cause of the Labrador current's vagaries and the whole subject of ice movements is one that scarcely lends itself to prediction. It is simply known in a general way that on the Grand Bank of Newfoundland bergs often move southward or southeastward. Those that drift westward of Cape Race usually pass between Green and St. Pierre banks.
The iceberg that glints in the path of a steamer on the Grand Bank may not be of this year's "calving." Indeed, it may have been broken from its parent glacier years before. It has been figured by the Hydrographic Office that if bergs were liberated principally in July and August, they should reach the transatlantic routes in December and January. This, however, is rare. Evidently the irregular coast of Labrador must considerably arrest the flow, when it is considered that bergs are most numerous during the early summer off the Bank. Of two bergs set adrift on the dame day, one may reach the Grand Bank two years before the other.