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petrology,branch of geology specifically concerned with the origin, composition, structure, and properties of rocksrock,
aggregation of solid matter composed of one or more of the minerals forming the earth's crust. The scientific study of rocks is called petrology. Rocks are commonly divided, according to their origin, into three major classes—igneous, sedimentary, and metamorphic.
..... Click the link for more information. , primarily igneous and metamorphic, and secondarily sedimentary. It includes petrography, the systematic description and classification of rocks using microscopic examination of rock in thin sections; and petrogenesis, which deals with the origin and formation of the various kinds of rock. Petrology is also concerned with the laboratory simulation of rock-forming processes and the application of principles of physical chemistry to natural environments. Petrologic analyses of oceanic rocks have given insights into plate tectonicplate tectonics,
theory that unifies many of the features and characteristics of continental drift and seafloor spreading into a coherent model and has revolutionized geologists' understanding of continents, ocean basins, mountains, and earth history.
..... Click the link for more information. processes, especially rock from mid-oceanic ridges, which may be formed from magma derived from deep in the mantlemantle,
portion of the earth's interior lying beneath the crust and above the core. No direct observation of the mantle, or its upper boundary, has been made; its boundaries have been determined solely by abrupt changes in the velocities and character of seismic waves passing
..... Click the link for more information. . Lunar rocks returned by Apollo astronauts were studied with petrographic techniques providing a wealth of information on the makeup and origin of the moon.
the science of rocks. In the USSR, some scientists—for example, F. Iu. Levinson-Lessing and D. S. Beliankin —regard “petrology” and “petrography” as synonyms. According to others, such as A. N. Zavaritskii, petrography deals with just the description of rocks, while petrology is concerned with genetic problems and theoretical constructions based on petrographic descriptions and experimental research.