As part of an US Coast Guard project on detection of destruction of icebergs, Dr. Budinger used thermite bombs and high explosives. These studies as well as studies of the radar capability to detect icebergs demonstrated their indestructibility and the difficulty of detection by radar in rough seas. The study is done in 1959-60 under pin the current rules for speed reduction of merchant and passenger ships in to fog.

(Assorted quotes from an article in Encyclopaedia Britannica Volume 9, pages 154-161, written originally by Thomas Budinger --date unknown--. Abstract compiled by Kaolin Fire Stockinger)

Icebergs

Ice in the waters of the earth's polar regions occurs in two forms, namely, pack ice and icebergs. Pack ice forms from seawater and is generally only one or two years old, whereas icebergs are fragments of ice sheets and glaciers that formed on land areas during intervals of thousands of years. When snow and freezing rain continue to precipitate over a continent in excess of evaporation, glaciers will form and icebergs will break off their ends and appear in the surrounding ocean.

There are many specific ways icebergs are broken off of the main glacial chunks. At the point where glaciers meet the sea, water pressure beneath the glacier tongue interacts with the outward creeping glacier. The tides, which have ranges up to 20 feet in the Arctic, result in an intermitting increase and decrease in force on the protruding end of the glacier resulting in the birth of a large monolith of drifting ice. Another way an iceberg is formed, which is characteristic of southern Greenland glaciers, consists of a melting or evaporation of the surface portions of the glaciernear its terminus at a greater rate than the water erosion on its underside. This results in an underwater shelf and eventually, through the erosion of water and periodic tidal and other hydraulic forces, this is broken off anf an iceberg floats to the surface. A third mechanism by which icebergs are formed is through gradual break off from a hanging glacier or ice shelf. The type of iceberg mechanism is related to the surrounding topography, the climate, and the rate of flow associated with the glaciers.

The speed of the ice sheet spread, or creep, over Greenland and the Antarctic caries from zero near their centres to as much as six miles per year in the ice streams that make up glaciers. For the same inclination relative to gravity, ice moves one ten-thousandth as fast as water. The average movement in the Arctic is 360 metres per year, with most of the measurements between extremes of 110 and 1100 metres per year. Very wide glaciers that move slowly produce only very small icebergs, in contrast to the rapidly moving glaciers.

Arctic icebergs vary in size from the size of a large piano to the dimensions of a ten-story building. Many icebergs in the Arctic are about 45 metres tall and 180 metres long. Icebergs of the Antarctic not only are far more abundant but are of enormous dimensions compared to those in the Arctic. Ninety-three percent of the world's mass of icebergs is found surrounding the Antarctic. Antarctic icebergs are characterized by their tremendous size and tabular shape. Lengths up to five miles are not unusal, with ice 45 metres above water. Most Antarctic icebergs are formed from the Antarctic continental ice sheet as it thins toward the coast and exudes into the ocean as a great ice shelf with fronts hundreds of miles long.

Iceberg movement is influenced by direct wind push on its exposed are to an extent far freater than commonly assumed. Although the bulk of the iceberg is below water, in many situations wind has a dominant influence on the movement. The day-to-day movement of an iceberg is controlled by the size and shape of the iceberg, previous and present wind, surface wind current, and general ocean current. The most important factor in assessing wind drift of icebergs is size and shape. Although most icebergs have a specific gravity of .9, this only means that six-sevenths of the mass is below the sea surface when the iceberg is rectangular, blocky, or flat-topped. Winged icebergs, those with sail-like pinnacles around the central mass, are very much influenced by the winds and move at speeds of one knot per day under the influence of steady winds of 30 knots. The wind force on an iceberg foes not result in movment directly downwind, but because of the rotation of the earth, windage on an iceberg is 30 to 50 degrees to the right in the Northern hemisphere and to the left in the Souther Hemisphere. The momentum of icebergs is so great that once in motion they continue for hours after the wind has abated.

Icebergs transport sediment in the form of pebbles, cobbles, boulders, and finer material, and even plant and animal life, thousands of miles from their source areas. Bottom freezing of ice shelves and reduction of the ice surface results in migration of sediments and organisms upward. Layering of sediment can be seen in sea-ice floes and icebergs from ice shelves. Thicknesses of as much as 130 centimetres of glacial till have been noted on the ocean floor from discharges by icebergsm aooarently during the last one million years. Icebergs are coloured brown, black, and green by a combination of sediment, plankton deposits under the source area ice shelf, and glacial blue ice.

In the open ocean most ice is seen by radar at ranges depending upon fragment size, but smaller icebergs can only be detected when the sea surface is calm, and then only at ranges of about one mile. Neither radar not sonar can be relied upon for detection of icebergs in choppy seas. Sonar's effectiveness is limited by the water conditions and speed of comercial vessels.

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