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Oligocene epoch
(Encyclopedia)Oligocene epoch ŏlˈəgōsēnˌ [key], third epoch of the Tertiary period in the Cenozoic era of geologic time, lasting from 38 to 24 million years ago. More of North America was dry land during the ...Ngami, Lake
(Encyclopedia)Ngami, Lake əng-gäˈmē, ng– [key], 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. Since ...Baltic Shield
(Encyclopedia)Baltic Shield, the continental core of Europe, composed of Precambrian crystalline rock, the oldest of Europe. The tectonically stable region was not affected by the Caledonian, Hercynian, and Alpine ...Agassiz, Lake
(Encyclopedia)Agassiz, Lake ăgˈəsē [key], glacial lake of the Pleistocene epoch, c.700 mi (1,130 km) long, 250 mi (400 km) wide, formed by the melting of the continental ice sheet beginning some 14,000 years ag...glacial periods
(Encyclopedia)glacial periods, times during which large portions of the earth's surface were covered with thick glacial ice sheets. In the Pleistocene epoch, in the Carboniferous and Permian periods of the Paleozoi...megatherium
(Encyclopedia)megatherium mĕgəthērˈēəm [key] [Gr.,=large beast], extinct ground sloth, of the genus Megatherium, that was widely distributed in North and South America in the Pleistocene epoch. Fossil evidenc...flint, mineral
(Encyclopedia)flint, variety of quartz that commonly occurs in rounded nodules and whose crystal structure is not visible to the naked eye. Flint is dark gray, smoky brown, or black in color; pale gray flint is cal...Bonneville Salt Flats
(Encyclopedia)Bonneville Salt Flats bŏnˈəvĭl, bŏˈnēvĭl, bŏnˈvĭl [key], desert area in Tooele co., NW Utah, c.14 mi (22.5 km) long and 7 mi (11.2 km) wide. The smooth salt surface of the Flats is ideal fo...Boucher de Crèvecœur de Perthes, Jacques
(Encyclopedia)Boucher de Crèvecœur de Perthes, Jacques də krĕvkörˈ də pĕrt [key], 1788–1868, French writer and archaeologist. He was the first to provide evidence that humans had existed in the Pleistocen...Quaternary period
(Encyclopedia)Quaternary period kwətûrˈnərē [key], younger of the two geologic periods of the Cenozoic era of geologic time (see Geologic Timescale, tablegeologic timescale, table) from 2 millon years ago to t...Browse by Subject
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