Science Fact Finder | The Earth - How Much Of The Earth's Surface Is Permanently Frozen?

How much of the Earth's surface is permanently frozen?

About one-fifth of the Earth's land contains permafrost, an underground layer that remains frozen year-round. The permanently frozen layer may be bedrock, sod, ice, sand, gravel, or any other type of material that has been frozen for at least two years. Nearly all permafrost is thousands of years old and is located in the polar and subpolar regions of the Earth.

Sources: Considine, Glenn D. Van Nostrand's Scientific Encyclopedia, 8th ed., vol. 1, p. 363; Dyson, James L. The World of Ice, p. 149; World Book Encyclopedia, vol. 15, p. 289.

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