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mass extinction

(Encyclopedia)mass extinction, the extinction of a large percentage of the earth's species, opening ecological niches for other species to fill. There have been at least ten such events. The five greatest were thos...

flood, in hydrology

(Encyclopedia)flood, inundation of land by the rise and overflow of a body of water. Floods occur most commonly when water from heavy rainfall, from melting ice and snow, or from a combination of these exceeds the ...

fern

(Encyclopedia)CE5 Life cycle of a fern fern, any plant of the division Polypodiophyta. Fern species, numbering several thousand, are found throughout the world but are especially abundant in tropical rain fores...

sewerage

(Encyclopedia)sewerage, system for the removal and disposal of chiefly liquid wastes and of rainwater, which are collectively called sewage. The average person in the industrialized world produces between 60 and 14...

utility, public

(Encyclopedia)utility, public, industry required by law to render adequate service in its field at reasonable prices to all who apply for it. Public utilities frequently operate as monopolies in their market. In th...

energy, sources of

(Encyclopedia)energy, sources of, origins of the power used for transportation, for heat and light in dwelling and working areas, and for the manufacture of goods of all kinds, among other applications. The develop...

Singapore

(Encyclopedia)CE5 Singapore sĭngˈgəpôr, sĭngˈə–, sĭngˌgəpôrˈ [key], officially Republic of Singapore, republic (2015 est. pop. 5,535,000), 299 sq mi (774 sq km). It consists of the island of Singap...

mining

(Encyclopedia)mining, extraction of solid mineral resources from the earth. These resources include ores, which contain commercially valuable amounts of metals, such as iron and aluminum; precious stones, such as d...

São Tomé and Principe

(Encyclopedia)CE5 São Tomé and Principe prēnˈsēpə [key], officially Democratic Republic of São Tomé and Principe, republic (2015 est. pop. 196,000), 372 sq mi (964 sq km), W Africa, in the Gulf of Guinea...

atmosphere

(Encyclopedia)CE5 Atmosphere atmosphere [Gr.,=sphere of air], the mixture of gases surrounding a celestial body with sufficient gravity to maintain it. Although some details about the atmospheres of other plane...