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lichen

(Encyclopedia)lichen līˈkən [key], usually slow-growing organism of simple structure, composed of fungi (see Fungi) and photosynthetic green algae or cyanobacteria living together in a symbiotic relationship and...

island

(Encyclopedia)island, relatively small body of land surrounded entirely by water. (As the oceans form a continuous mass of water on the earth's surface, all continents are islands in the strict sense of the word.) ...

poison gas

(Encyclopedia)poison gas, any of various gases sometimes used in warfare or riot control because of their poisonous or corrosive nature. These gases may be roughly grouped according to the portal of entry into the ...

tornado

(Encyclopedia)tornado, dark, funnel-shaped cloud containing violently rotating air that develops below a heavy cumulonimbus cloud mass and extends toward the earth. The funnel twists about, rises and falls, and whe...

pulsar

(Encyclopedia)pulsar, in astronomy, a neutron star that emits brief, sharp pulses of energy instead of the steady radiation associated with other natural sources. The study of pulsars began when Antony Hewish and h...

Welles, Orson

(Encyclopedia)Welles, Orson, 1915–85, American actor, director, and producer, b. Kenosha, Wis. From childhood he evinced a precocious talent and lofty sense of self-assurance in theatrical matters. He began actin...

sea level

(Encyclopedia)sea level, the level of the sea, which serves as the datum used for measurement of land elevations and ocean depths. Theoretically, one would expect sea level to be a fixed and permanent horizontal su...

Patagonia

(Encyclopedia)Patagonia pätägōˈnyä [key], region, c.300,000 sq mi (777,000 sq km), primarily in S Argentina, S of the Río Colorado and E of the Andes, but including extreme SE Chile and N Tierra del Fuego. Pa...

sand

(Encyclopedia)sand, rock material occurring in the form of loose, rounded or angular grains, varying in size from .06 mm to 2 mm in diameter, the particles being smaller than those of gravel and larger than those o...

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