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silt
(Encyclopedia)silt, predominantly quartz mineral particles that are between sand size and clay size, i.e., between 1⁄16 and 1⁄256 mm (1⁄406 –1⁄6502 in.) in diameter. Silt, like clay and sand, is a product...rhyolite
(Encyclopedia)rhyolite, fine-grained light-colored acidic volcanic rock. Rhyolite is chemically the equivalent of granite, and is thus composed primarily of quartz and orthoclase feldspar with subordinate amounts o...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 ...Great Artesian Basin
(Encyclopedia)Great Artesian Basin, c.670,000 sq mi (1,735,300 sq km), between the Eastern Highlands and the Western Plateau, E central Australia, extending S from the Gulf of Carpentaria, Queensland, to NE South A...Janesville
(Encyclopedia)Janesville, city (1990 pop. 52,133), seat of Rock co., S central Wis., on the Rock River; inc. 1853. It is an industrial and commercial center in a grain, dairy farm, and tobacco area. Manufactures in...Who, The
(Encyclopedia) Who, The, English rock music group formed in 1964. The members were Peter Dennis Blanford Townshend, 1945–, Chiswick, London, U.K., guitar, ...sandstone
(Encyclopedia)sandstone, sedimentary rock formed by the cementing together of grains of sand. The usual cementing material in sandstone is calcium carbonate, iron oxides, or silica, and the hardness of sandstone va...joint, in geology
(Encyclopedia)joint, in geology, fracture in rocks along which no appreciable movement has occurred (see fault). Nearly vertical, or sheet, joints that result from shrinkage during cooling are commonly found in ign...Devonian period
(Encyclopedia)Devonian period dĭvōˈnēən [key], fourth period of the Paleozoic era of geologic time between 408 and 360 million years ago (see Geologic Timescale, tablegeologic timescale, table). It was named (...Arches National Park
(Encyclopedia)Arches National Park, 76,519 acres (30,979 hectares), E Utah; est. as a national monument 1929, designated a national park 1971. Located in red-rock country and overlooking the gorge of the Colorado R...Browse by Subject
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