CALDERA encyclopedia topics

Valles Caldera National Preserve, 88,900 acres (36,000 hectares), N N.Mex.; est. 2000. Formerly part of the vast, privately owned Baca Ranch, the preserve lies at the heart of the Valle Grande (Jemez) Mountains and encompasses most of a 12-15 mi- (19-24 km-) wide circular caldera, a sunken volcano formed by the collapse of volcanic domes after two massive eruptions about 1.6 and 1.2 million years ago. The basin is some 3,000 ft (915 m) deep, measured from the surrounding rim, which encircles several lava-dome mountains. The landscape is mainly a mixture of grasslands and forested mountains, cut by numerous streams. Like other calderas, it has hot springs, gas vents, and other volcanic features. Wildlife include 17 threatened or endangered species such as the Mexican spotted owl, goshawk, Jemez Mountains salamander, and Rio Grande cutthroat trout. The preserve also is home to elk, mule deer, black bears, mountain lions, coyotes, bobcats, and other mammals, and golden and bald eagles and other birds.

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Caldera Rodríguez, Rafael

Caldera Rodríguez, Rafael, 1916-, president of Venezuela (1969-74, 1994-99). A lawyer and professor of sociology, he was first elected to the chamber of deputies in 1941 and was a founder of the center-right Social Christian party in 1946. He was imprisoned several times during the dictatorial regime of Marcos Pérez Jiménez, which he opposed. After the dictator's overthrow, Caldera ran (1958) unsuccessfully for the presidency; he served instead as president of the chamber of deputies. In the elections of Dec., 1969, he won the presidency with barely 30% of the vote. Faced with an uncooperative congress, he had difficulty in getting legislation passed. He was awarded a life seat in the senate at the end of his term but was again elected president, this time as the candidate of the National Convergence party, when Carlos Andrés Pérez was removed from office on corruption charges in 1993.

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Licensed from Columbia University Press

caldera

Large, bowl-shaped volcanic depression that forms when the top of a volcanic cone collapses into the space left after magma is ejected during a violent volcanic eruption. The term is Spanish for “caldron.” Subsequent minor eruptions may build small cones on the floor of the caldera which may still later fill up with water; an example is Crater Lake in Oregon.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.