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HOW GLACIERS FORM?

Some of the snow on a high mountaintop melts and runs off.
But much of it stays all year round.
The snow that stays becomes hard and grainy, like salt.
As new snow falls each year, the grainy snow underneath is squeezed together and becomes hard as ice.
The weight of all the snow pressing down squeezes out a stream of ice, like toothpaste is squeezed from a tube.
This gigantic stream of ice, creeping down the mountainside, is called a glacier.

Black Rapids Glacier in September 1986. (photograph by Rod March). http://ak.water.usgs.gov/glaciology/black_rapids/

 TYPES OF GLACIERS

There are two main kinds of glaciers.
One kind is like a river of ice. It stretches from near the top of a mountain down into a valley below.
The other kind of glacier is like an enormous cake of ice and snow. This kind covers whole mountain ranges and even whole lands. All the land at the South Pole is covered by such a glacier.
Most glaciers move slowly. They travel from only a few inches (centimeters) to about forty feet (12 meters) a day.
But, slow as it is, a glacier is like a big, icy bulldozer. It scrapes, gouges, and shovels up the ground over which it moves.
It picks up everything in its path, from soil to huge boulders, and carries it along. As a glacier passes through a valley, it may dig the valley deeper and wider.
As it moves down a mountainside, it may leave long scratches and furrows.
Glaciers make valleys wider and dig out holes for lakes. Long ago, during the time that is called the Ice Age, great glaciers crept far across the land. They dug many ditches and deep holes in some of the places they passed over. Later, these holes filled up with water and became lakes.
In some places the glaciers left rich soil that they had picked up as they moved.
In other places, they left behind huge boulders that now sit far from the mountains that were once their home.

Do you know what it is like at the center of the earth?

It is very, very hot.
The temperature is thought to be about 13,000 °F (7000 °C), which is hot enough to melt rock.

The heat spreads to the rock around the center of the earth and to water trapped between the layers of rock. In some parts of the world, this hot water is close to the earth’s surface. By pumping it out of the ground as hot water or steam, engineers have tapped a new source of energy. This energy is called geothermal energy, which means it is heat energy from under the ground.

Tropical fruit grows in Iceland!

Hot water from inside the earth may be used directly to heat buildings. In Iceland, where there are many hot springs, hot water heats greenhouses and swimming pools as well as homes. And although Iceland is close to the Arctic Ocean, people living there can grow bananas and other tropical fruit in their greenhouses!

Steam condenses into white clouds of water vapor rising from these hot springs in Iceland. Several countries have developed geothermal power plants to heat homes and generate electricity.

In one kind of geothermal power station, cold water is pumped down a pipe into the earth and is heated     by hot rock. Another pipe brings the hot water to the surface.

Several countries in the world, including the United States, Italy, and New Zealand, have built geothermal power stations. Steam, coming out of the ground at high pressure, is used to run steam turbines that generate electricity.
Engineers are trying to find out how more countries might use geothermal energy.
They started with a question. If the rock below the surface is hot but there is no water down there, why not drill a hole through the rock, pump cold water down and let the rock heat it up? Then the water could be pumped up again through a second hole.
Some engineers are working on an even better idea. They want to build a geothermal power station underground, which would generate electricity. Then only an electric cable would be needed to bring the electrical energy to the surface of the earth.