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  • Glaciers are also called slow-moving rivers of ice. Most common in the polar regions of

  • the Arctic and Antarctic, glaciers can be found in the mountains of every continent

  • except Australia. Glaciers form in places where snow accumulates over time. It takes

  • decades, or even centuries, for glaciers to form. As the snow deepens, the weight and

  • pressure of the snow on top compresses the lower layers into ice. The weight of the glacier

  • plus the force of gravity will gradually cause the glacier to move downhill. Most glaciers

  • move very slowly, only about 160 feet or 50 meters per year, but some move as fast as

  • 100 feet or 30 meters per day.

  • Glaciers are powerful. They can carve huge chunks out of mountains as they move downhill.

  • Because of this, they are sometimes called 'nature's bulldozers.' Like bulldozers, they

  • shape the land as they pass over it, but they do this in several ways.

  • First, glaciers pick up any material lying on the ground beneath where snow accumulates.

  • Water beneath the glacier soaks into cracks in the rock below. As the water freezes, it

  • forces the cracks wider and breaks off pieces of rock. This is called freeze-thaw weathering.

  • As the glacier flows downhill, it takes these loose pieces with it. This is called erosion.

  • These rocks and stones scrape along the glacier bed like sandpaper, taking more rocks and

  • stones with them. The ground beneath it becomes smooth as the glacier moves over it - this

  • is called abrasion. The glacier transports the eroded material downhill with it. Sometimes

  • you can see dirt and rocks in a glacier, which will give it a dirty appearance.

  • Once the glacier flows far enough downhill that temperatures are warmer, it begins to

  • melt. Anything that can't melt, like rocks, stones, sand, and clay, is deposited or left

  • behind as glacial till. The ice turns into meltwater and flows farther downhill to join

  • a lake, stream, or ocean. If a glacier reaches a body of water, pieces of it may break off

  • and fall into the water, forming icebergs.

  • Glaciers are only found in very cold parts of the earth, but during the last ice age

  • they could be found in parts of the world that are much warmer now. Even though the

  • ice is melted now, the landforms created by the movement of ancient glaciers can still

  • be seen today. Glaciers can create lakes, valleys, and other landforms, and are the

  • largest sources of fresh water in the world. As they move, glaciers change the shape of

  • the earth, making them one of the most dynamic natural features on the planet.

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B2 中高級 美國腔

孩子們的冰川:冰川如何形成和侵蝕形成地貌 - FreeSchool (All About Glaciers for Kids: How Glaciers Form and Erode to Create Landforms - FreeSchool)

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    王杰 發佈於 2021 年 01 月 14 日
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