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Plate Geology

Decent Essays

Structural Geology and Plate Tectonics
Geology is an overall study of planet Earth—“its composition, structure, process, and history” (Shipman, Todd, & Wilson 602). Geology also plays a role in the study of the Moon and other solar system objects is primarily the province of astronomy. “None of the remarkable scientific advances of the twentieth century revealed with certainty the composition and structure of the Earth’s interior” (603). Present ideas presently rest on indirect evidence provided by earthquake body waves, their speed and direction identifying the types of materials through which they move, meteorites whose composition is believed to be similar to the Earth’s, spacecraft measurements of gravity and magnetic variations, and laboratory …show more content…

Ultramafic rocks have special significance, in that they probably are derived from the mantle. They are relatively unstable on the Earth’s surface, and are typically metamorphosed. In nature and in simplistic interpretation, igneous rocks that make up most continental crust typically have a felsic composition (such as rhyolite and granite). The mafic rock basalt is the dominant rock type that makes up most ocean crust. Rocks of intermediate composition are derived from the mixing of continental and oceanic crust (USGS …show more content…

However, it was not until this century that nuclear age technology was developed that uses measurements of radioactivity in certain types of rocks to give us ages in numbers of years. These ages, usually called radiometric ages, are used in conjunction with relative dating principles to determine at least an approximate age for most of the world 's major rock formations (USGS). “Radiometric dating is the determination of age by using radioactivity, has become geology’s best tool for establishing absolute geologic time” (Shipman, Todd, & Wilson 704). The atomic nuclei that decay of their own accord are said to be radioactive. The decay product—or daughter nucleus, as it is commonly called—may be stable. If so, the transformation reaches completion in a single step. However, the daughter nuclei of many naturally occurring isotopes are themselves radioactive and hence undergo further decay”

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