Columbia Encyclopedia

(Encyclopedia) petroleum, oily, flammable liquid that occurs naturally in deposits, usually beneath the surface of the earth; it is also called crude oil. It consists principally of a mixture of hydrocarbons, with t...

(Encyclopedia) mountain, high land mass projecting conspicuously above its surroundings and usually of limited width at its summit. Although isolated mountains are not unusual, mountains commonly form ranges, compri...

(Encyclopedia) tunnel, underground passage usually made without removing the overlying rock or soil. Although tunnels are approximately horizontal, they must be built with sufficient gradient for proper drainage. Tu...

(Encyclopedia)  CE5 Northwest Territories, territory (2001 pop. 37,360), 532,643 sq mi (1,379,028 sq km), NW Canada. The Northwest Territories lie W of Nunavut, N of lat. 60°N, and E of Yukon. Until 1999, when th...

(Encyclopedia) wolf, carnivorous mammal of the genus Canis in the dog family. Once distributed over most of the Northern Hemisphere, wild wolves are now confined to the wilder parts of a reduced range. Three wolf sp...

(Encyclopedia) pollution, contamination of the environment as a result of human activities. The term pollution refers primarily to the fouling of air, water, and land by wastes (see air pollution; water pollution; s...

(Encyclopedia) bat, winged mammal of the order Chiroptera, which includes 900–1,000 species classified in about 200 genera and 17 families. Bats range in size from a wingspread of over 5 ft (150 cm) to a wingsprea...

(Encyclopedia) San Francisco săn frănsĭsˈkō [key], city (2020 pop. 873,965), coextensive with San Francisco co., W ...

(Encyclopedia)  CE5 Minnesota mĭnˌĭsōˈtə [key], upper midwestern state of the United States. It is bordered by Lake Superior and Wisconsin (E), Iowa (S), South Dakota and North Dakota (W), and the Canadian p...

(Encyclopedia)  National Parks and Monuments 1 National Parks and Monuments National Monuments National and International Historic Sites and Historical Parks National Memorials National Battlef...