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Lahontan, Lake

(Encyclopedia) Lahontan, Lake lhn´tn, extinct lake of W Nev. and NE Calif. It was formed by heavy precipitation caused by the Pleistocene glaciers and with Lake Bonneville (see under Bonneville…

Pleistocene epoch

(Encyclopedia) Pleistocene epoch pl´stsn, 6th epoch of the Cenozoic era of geologic time (see Geologic Timescale, table). According to a classification that considered its deposits to have been…

Ice Age

(Encyclopedia) Ice Age: see Pleistocene epoch.

atlatl

(Encyclopedia) atlatl ät´lätl [Nahuatl], device used to throw a spear with greater propulsion. Atlatls began to be used in the Americas in the post-Pleistocene period and were eventually replaced by…

epoch

(Encyclopedia) epoch, unit of geologic time that is a subdivision of a period. The Pleistocene and Holocene epochs, for example, are divisions of the Quaternary period. Epoch is also used to describe…

mastodon

(Encyclopedia) mastodon ms´tdn, name for a number of prehistoric mammals of the extinct genus Mammut, from which modern elephants are believed to have developed. The earliest known forms lived in…

Quaternary period

(Encyclopedia) Quaternary period kwtûr´nr, younger of the two geologic periods of the Cenozoic era of geologic time (see Geologic Timescale, table) from 2 millon years ago to the present.…

Ngami, Lake

(Encyclopedia) Ngami, Lake ng-gä´m, ng–, reedy marsh, c.40 mi (64 km) long and from 4 to 8 mi (6.4–12.9 km) wide, NW Botswana. During the Pleistocene epoch, the lake covered an extensive area.…

Boucher de Crèvecœur de Perthes, Jacques

(Encyclopedia) Boucher de Crèvecœur de Perthes, Jacques zhäk boosh´ d krvkör´ d prt, 1788–1868, French writer and archaeologist. He was the first to provide evidence that humans had existed in…

Geologic Timescale

(Encyclopedia) Geologic TimescaleEraPeriodEpochApproximate duration(millions of years)Approximate number of years ago(millions of years)1 Not an era but the time preceding the Cambrian.…