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61Plate tectonics — The tectonic plates of the world were mapped in the second half of the 20th century …
62earth — /errth/, n. 1. (often cap.) the planet third in order from the sun, having an equatorial diameter of 7926 mi. (12,755 km) and a polar diameter of 7900 mi. (12,714 km), a mean distance from the sun of 92.9 million mi. (149.6 million km), and a… …
63dating — I In geology and archaeology, the process of determining an object s or event s place within a chronological scheme. Scientists may use either relative dating, in which items are sequenced on the basis of stratigraphic clues (see stratigraphy) or …
64Geology of Mars — Mars   Mars as seen by the Hubble Space Telescope Designations …
65moon — mooner, n. moonless, adj. /moohn/, n. 1. the earth s natural satellite, orbiting the earth at a mean distance of 238,857 miles (384,393 km) and having a diameter of 2160 miles (3476 km). 2. this body during a particular lunar month, or during a… …
66Moon — /moohn/, n. Sun Myung /sun myung/, born 1920, Korean religious leader: founder of the Unification Church. * * * Sole natural satellite of Earth, which it orbits from west to east at a mean distance of about 238,900 mi (384,400 km). It is less… …
67Precambrian time — Interval of geologic time from с 3. 8 billion years ago, the age of the oldest known rocks, to 544 million years ago, the beginning of the Cambrian Period. This interval represents more than 80% of the geologic record and thus provides important… …
68Geology of the Iberian Peninsula — The geology of the Iberian Peninsula consists of the study of the rock formations on the Iberian Peninsula, which includes Spain, Portugal, Andorra, and Gibraltar. The peninsula contains rocks from every age from Ediacaran to Recent, and almost… …
69History of the Earth — For the history of modern humans, see History of the world. Geological time put in a diagram called a geological clock, showing the relative lengths of the eons of the Earth s history The history of the Earth describes the most important events… …
70Mantle (geology) — For other uses, see Mantle (disambiguation). Earth cutaway from core to exosphere. The mantle is a part of a terrestrial planet or other rocky body large enough to have differentiation by density. The interior of the Earth, similar to the other… …
