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Directions: Please read the following passage within the limited time, and then do the exercise.
Length of Text:
400
words
Time
Allowed: 4 minutes
9. Icebergs
1
Floating icebergs are at once the dread of sailors and the wonder of all who see them for the first time. They are the broken-off ends of glaciers that slide into the sea. Some are small and flat. Others form mountains of ice a mile (1.6 kilometers) or more across and more than 200 feet (61 meters) above the water.
2
Hiding beneath the sea is the largest part of an iceberg. This part is about seven times as large as the part above. This is because an iceberg is made of freshwater ice, which weighs about seven-eighths as much as seawater. In freshwater, an iceberg would sink down until about nine-tenths was below the surface.
3
These wanderers of the sea are often surrounded by fog. On clear days, they shimmer in the sun with dazzling beauty, reflecting the tints of sea and sky. As they drift, many take on the shapes of castles, arches, and domes. At night, the bergs glow with an odd whiteness called blink. Blink is the reflection of weak light rays from the crystal surface.
4
New icebergs are being formed all the time. Most of those in the north Atlantic break off from the fringes of Greenland's great icecap. Here in the early spring thaws, a great parade of floating ice islands begins its journey southward. Sometime in April, May, or June, an average of 400 reach the northern Atlantic shipping routes.
5
Icebergs melt quickly in salt water. High waves and heavy swells rush the process. As they dissolve, icebergs may split in two, roll over, or slough off great fragments with a vast roar. Some bergs, however, are so huge that they travel 2,000 miles (3,200 kilometers) or more before disappearing.
6
Two shipping routes are especially dangerous: one through the Strait of Belle Isle into the Gulf of St. Lawrence, the other along the Grand Banks. Since 1914, the United States Coast Guard has conducted an ice patrol in the North Atlantic. This service is financed by the maritime nations. Reports of the positions and movements of icebergs are broadcast by radio. The Hydrographic Office issues bulletins that chart the iceberg region. The office also provides charts showing safe “tracks” for shipping. The Coast Guard equips its cutters and planes with radar and loran to fix the location of icebergs. In addition, other sound equipment is lowered into the sea to help locate bergs.
Comprehension Exercise