seafloor spreading
91Indian Ocean — an ocean S of Asia, E of Africa, and W of Australia. 28,357,000 sq. mi. (73,444,630 sq. km). * * * Indian Ocean Introduction Indian Ocean Background: The Indian Ocean is the third largest of the world s five oceans (after the Pacific Ocean and… …
92rift valley — Geol. 1. graben. 2. a subsea chasm extending along the crest of a mid ocean ridge, locus of the magma upwellings that accompany seafloor spreading. [1890 95] * * * Elongated trough formed by the subsidence of a segment of the Earth s crust… …
93South China Sea — a part of the W Pacific, bounded by SE China, Vietnam, the Malay Peninsula, Borneo, and the Philippines. Also called Nan Hai. * * * ▪ sea, Pacific Ocean Introduction Chinese Nan Hai arm of the western Pacific Ocean that borders the Southeast… …
94tectonics — /tek ton iks/, n. (used with a sing. v.) 1. the science or art of assembling, shaping, or ornamenting materials in construction; the constructive arts in general. 2. See structural geology. [1625 35; see TECTONIC, ICS] * * * Scientific study of… …
95Mesozoic Era — Second of the Earth s three major geologic eras and the interval during which the continental landmasses as known today were separated from the supercontinents Laurasia and Gondwana by continental drift. It lasted from с 248 to с 65 million years …
96marine geophysics — Subdiscipline of geophysics that is concerned with ocean phenomena. The main techniques and areas of study include heat flow data, seismic reflection and refraction techniques, geomagnetics, and gravity studies. The principal concepts in marine… …
97Tharp, Marie — ▪ 2007 American oceanographic cartographer (b. July 30, 1920, Ypsilanti, Mich. d. Aug. 23, 2006, Nyack, N.Y.), pioneered ocean floor mapping, which provided crucial support for the acceptance of seafloor spreading and continental drift.… …
98Dietz, Robert S. — ▪ American geophysicist in full Robert Sinclair Dietz born Sept. 14, 1914, Westfield, N.J., U.S. died May 19, 1995, Tempe, Ariz. American geophysicist and oceanographer who set forth a theory of seafloor spreading (seafloor spreading… …
99Mississippian Subperiod — ▪ geochronology first major subdivision of the Carboniferous Period, lasting from 359.2 to 318.1 million years ago. The Mississippian is characterized by shallow water limestone deposits occupying the interiors of continents, especially in… …
100Cayman Trough — Coordinates: 18°30′N 83°0′W / 18.5°N 83°W / 18.5; 83 …
