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gneiss
(Encyclopedia)gneiss nīs [key], coarse-grained, imperfectly foliated, or layered, metamorphic rock. Gneiss is characterized by alternating light and dark bands differing in mineral composition and having coarser g...Paleozoic era
(Encyclopedia)Paleozoic era pāˌlēəzōˈĭk [key], a major division (era) of geologic time (see Geologic Timescale, tablegeologic timescale, table) occurring between 570 to 240 million years ago. It is subdivide...schist
(Encyclopedia)schist shĭst [key], metamorphic rock having a foliated, or plated, structure called schistosity in which the component flaky minerals are visible to the naked eye. Schists are distinguished from the ...Canadian Shield
(Encyclopedia)Canadian Shield or Laurentian Plateau lôrĕnˈchən [key], U-shaped region of ancient rock, the nucleus of North America, stretching N from the Great Lakes to the Arctic Ocean. Covering more than hal...Guiana Highlands
(Encyclopedia)Guiana Highlands, mountainous tableland, c.1,200 mi (1,930 km) long and from 200 to 600 mi (322–966 km) wide, N South America, bounded by the Orinoco and Amazon river basins, and by the coastal lowl...Geologic Timescale (table)
(Encyclopedia)Geologic Timescale 1 Not an era but the time preceding the Cambrian. ...paleontology
(Encyclopedia)paleontology pāˌlēəntŏlˈəjē [key] [Gr.,= study of early beings], science of the life of past geologic periods based on fossil remains. Knowledge of the existence of fossils dates back at least...Cambrian period
(Encyclopedia)Cambrian period [Lat. Cambria=Wales], first period of the Paleozoic geologic era (see Geologic Timescale, tablegeologic timescale, table) extending from approximately 570 to 505 million years ago. It ...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...Rocky Mountains
(Encyclopedia)Rocky Mountains, major mountain system of W North America and easternmost belt of the North American cordillera, extending more than 3,000 mi (4,800 km) from central N.Mex. to NW Alaska; Mt. Elbert (1...Browse by Subject
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