cracks of permafrost and frozen rocks

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• permafrost — /perr meuh frawst , frost /, n. (in arctic or subarctic regions) perennially frozen subsoil. Also called pergelisol. [1943; PERMA(NENT) + FROST] * * * Perennially frozen earth, with a temperature below 32 °F (0 °C) continuously for two years or… …   Universalium

• North America — North American. the northern continent of the Western Hemisphere, extending from Central America to the Arctic Ocean. Highest point, Mt. McKinley, 20,300 ft. (6187 m); lowest, Death Valley, 276 ft. (84 m) below sea level. 400,000,000 including… …   Universalium

• ice formation — Any mass of ice that occurs on the Earth s continents or surface waters. Such masses form wherever substantial amounts of liquid water freeze and remain in the solid state for some period of time. Examples include glaciers, icebergs, sea ice, and …   Universalium

• United States — a republic in the N Western Hemisphere comprising 48 conterminous states, the District of Columbia, and Alaska in North America, and Hawaii in the N Pacific. 267,954,767; conterminous United States, 3,022,387 sq. mi. (7,827,982 sq. km); with… …   Universalium

• Erosion — is the carrying away or displacement of solids (sediment, soil, rock and other particles) usually by the agents of currents such as, wind, water, or ice by downward or down slope movement in response to gravity or by living organisms (in the case …   Wikipedia

• Precambrian time — Interval of geologic time from с 3. 8 billion years ago, the age of the oldest known rocks, to 544 million years ago, the beginning of the Cambrian Period. This interval represents more than 80% of the geologic record and thus provides important… …   Universalium

• Dike (geology) — Banded gneiss with dike of granite orthogneiss. An intrusion (Notch Peak monzonite) inter fingers (partly as a dike …   Wikipedia

• glacial landform — ▪ geology Introduction  any product of flowing ice and meltwater. Such landforms are being produced today in glaciated areas, such as Greenland, Antarctica, and many of the world s higher mountain ranges. In addition, large expansions of present… …   Universalium

• Polar ecology — is the relationship between plants and animals in a polar environment. Polar environments are in the Arctic and Antarctic regions. Arctic regions are in the northern hemisphere, and it contains land and the islands that surround it. Antarctic is… …   Wikipedia

• Glacier — This article is about the geological formation. For other uses, see Glacier (disambiguation). The Baltoro Glacier in the Karakoram, Kashmir, Northern Pakistan. At 62 kilometres (39 mi) in length, it is one of the longest alpine glaciers on… …   Wikipedia

• Phoenix (spacecraft) — This article is about the Mars lander. For the Star Trek spacecraft, see Phoenix (Star Trek). For other uses, see Phoenix (disambiguation). Phoenix Mars Mission Artist s impression of the Phoenix spacecraft as it lands on Mars Operator NASA …   Wikipedia