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earth, in geology and astronomy
(Encyclopedia)CE5 A. Cross section of the earth, showing its shells B. Detailed cross section of the crust and upper mantle: The lithosphere consists of the hard rock in the crust and upper mantle, lying above t...chiton
(Encyclopedia)CE5 A. Dorsal view of a chiton, representative mollusk of the class Amphineura B. Internal anatomy of a chiton chiton kīˈtən [key], common name for rock-clinging marine mollusks of the class Po...Mohole, Project
(Encyclopedia)Mohole, Project, program proposed in 1957 to drill a hole down to the boundary between the crust and the mantle, known as the Mohorovičić discontinuity at about 4 to 43 mi (7 to 70 km) below the ear...Welsbach, Carl Auer, Baron von
(Encyclopedia)Welsbach, Carl Auer, Baron von kärl ouˈər bärōnˈ fən vĕlsˈbäkh [key], 1858–1929, Austrian chemist. He discovered the rare earth elements neodymium and praseodymium (1885) and lutetium (c.1...cowrie
(Encyclopedia)cowrie or cowry both: kouˈrē [key], common name applied to marine gastropods belonging to the family Cypraeidae, a well-developed family of marine snails found in the tropics. Cowries are abundant i...asthenosphere
(Encyclopedia)asthenosphere ăsthēnˈəsfēr [key], region in the upper mantle of the earth's interior, characterized by low-density, semiplastic (or partially molten) rock material chemically similar to the overl...pearl, gem
(Encyclopedia)pearl, hard, rounded secretion formed inside the shell of certain mollusks, used as a gem. It is secreted by the epithelial cells of the mantle, a curtain of tissue between the shell and body mass, an...mother-of-pearl
(Encyclopedia)mother-of-pearl or nacre nāˈkər [key], the iridescent substance that forms the lining of the shells of some fresh-water and some salt-water mollusks. Like the pearl it is a secretion of the mantle,...Mollusca
(Encyclopedia)Mollusca məlŭsˈkə [key], taxonomic name for the one of the largest phyla of invertebrate animals (Arthropoda is the largest) comprising more than 50,000 living mollusk species and about 35,000 fos...silicate
(Encyclopedia)silicate, chemical compound containing silicon, oxygen, and one or more metals, e.g., aluminum, barium, beryllium, calcium, iron, magnesium, manganese, potassium, sodium, or zirconium. Silicates may b...Browse by Subject
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