Icebergs are mountains of freshwater ice floating in the ocean. They are huge chunks broken off from the great masses of land ice calledglaciers. Almost all of Greenland and Antarctica are covered by glaciers the year round. Glaciers also cover parts of Alaska. They are formed by
layers of packed snow. Glacier may be thousands of meters thick. Their front ends, or tongues, reach down to the sea. At the coast the tips of
the tongues break off, plunge into the oceans, and become icebergs. This process is called calving. When calving occurs, a loud cracking noise
fills the air. Sometimes a low rumbling can be heard for hours before the ice actually breaks away. People close enough can hear the hissing of
air as it escapes from bubbles bursting in the ice along the break. Glaciers calve all year round. Just as many icebergs break off in winter as in
summer. But in winter their passageway to open the sea is often jammed with masses of frozen seawater. Icebergs pile up behind this jam of
sea ice. In the spring, when the ice block is broken, a whole fleet of icebergs may sail out toward the open ocean. Icebergs from the eastern
coast of Greenland drift southward. They are carried by the Greenland Current, which then swings them northward around the tip of the island.
Part of the way up the coast the icebergs are caught in the cold Labrador Current and carried southward toward Newfound-land on the way,
most of the icebergs become grounded among the many islands and bays along the Labrador coast. The others float on toward the open sea.
Off Newfoundland they are caught by a warm current from the south called the Gulf Stream. Icebergs that do not ground and remain in the
Labrador Current often enter the lanes used by ships crossing the Atlantic Ocean. An iceberg starts to break up almost as soon as it is afloat.
Cracks appear and become filled with water from ice that melts during the day. When this melted water freezes at night, it expands and widens
the cracks. The ice is weakened, and pieces of iceberg break off and float away. The iceberg becomes smaller and smaller. Most icebergs melt
completely within a few days of entering the Gulf Stream
What does the text tell us about ...?
Select one:
a. How far glaciers cover
b. What calving is
C. How iceberg is defined
d. What glaciers cover
e. How Icebergs exist​