Geological and Physical Science Terms

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Tectonic Plate

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A block of lithosphere that consists of the crust and the rigid, outermost part of the mantle.

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Isotope

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One of the two or more atoms that have the same number of protons (atomic number) but different numbers of neutrons (atomic mass).

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Mid Ocean Ridge

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A long undersea mountain chain that has a steep narrow valley at its center, forms as magma rises from the seafloor.

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Ocean Trench

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A long, narrow, and steep depression that forms on the ocean floor as a result of subduction of a tectonic plate, running parallel to volcanic islands or continental coastlines, and may be as deep as 11 km below sea level.

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Convection Current

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The continuous, circular movement of fluid (liquid or gas) caused by the transfer of heat, where warmer, less dense regions rise and cooler, denser regions sink, creating a flow pattern.

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Fault

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A fracture or zone of fractures in the Earth's crust along which there has been displacement of the sides relative to one another parallel to the fracture surface, as a result of tectonic forces.

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Hot Spot

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A location in the Earth's mantle where a column of hot magma rises through the lithosphere, often forming volcanic activity on the surface, independent of tectonic plate boundaries.

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Seafloor Spreading

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A geological process at divergent boundaries between tectonic plates, where magma rises from the mantle through cracks in the Earth's lithosphere, forming new oceanic crust and causing the seafloor to gradually widen.

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Density

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A physical property of matter defined as the amount of mass contained in a given volume, expressed mathematically as Density = Mass/Volume.

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Radioactive Decay

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A spontaneous process in which an unstable atomic nucleus loses energy by emitting radiation, transforming the atom into a different element or a more stable isotope.