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Definition
| A hypothesis that suggests that all present continents were once one main large formation that later broke apart and "drifted" from each other. |
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Definition
| A linear zone along which continental lithosphere stretches and pulls apart. Its creation may mark the beginning of a new ocean basin. |
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Definition
| Mountains formed in part by igneous activity associated with the subduction of oceanic lithosphere beneath a continent. Examples include the Andes and the Cascades. |
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Definition
| A boundary in which two plates move together, resulting in oceanic lithosphere being thrust beneath an overriding plate, eventually to be reabsorbed into the mantle. Can also come together to create mountain systems. |
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Definition
| The temperature above which a material loses its magnetization. |
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Definition
| A narrow, elongated depression of the seafloor. |
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Term
Divergent Boundary
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Spreading Center |
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Definition
| A boundary in which two plates move apart, resulting in upwelling of material from the mantle to create new seafloor. |
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Term
Fossil Magnetism
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Paleomagnetism |
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Definition
| The natural remnant magnetism in rock bodies. |
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Definition
| Linear zone of irregular topography on the deep-ocean floor that follows transform faults and their inactive extensions. |
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Definition
| A concentration of heat in the mantle. |
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Definition
| Chain of volcanic structures produces as a lithospheric plate moves over a mantle plume. |
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Term
Island Arc
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Volcanic Island Arc |
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Definition
| A chain of volcanic islands generally located a few hundred kilometers from a trench where there is active subduction of one oceanic plate beneath another. |
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Term
Lithospheric Plate
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Tectonic Plates |
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Definition
| A coherent unit of Earth's rigid outer layer that includes the crust and upper unit. |
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Term
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Definition
| A sensitive instrument used to measure the intensity of Earth's magnetic field at various points. |
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Term
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Definition
| A change in Earth's magnetic field from normal to reverse or vice versa. |
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Term
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Definition
| Time scale of Earth's magnetic field in the recent past. This time scale was developed by establishing the magnetic polarity for lava flows of known age. |
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Term
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Definition
| A mass of hotter-than-normal mantle material that ascends toward the surface, where it may lead to igneous activity. These plumes of solid yet mobile material may originate as deep as the core--- mantle boundary. |
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Term
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Definition
| A magnetic field the same as that which presently exists. |
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Term
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Definition
| Winds through all of the major oceans in a manner similar to the seam on a baseball. |
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Term
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Definition
| The proposed supercontinent that 200 million years ago began to break apart and form the present landmasses. |
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Term
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Definition
| The process by which most igneous rocks melt. Since individual minerals have different melting points, most igneous rocks melt over a temperature range of a few hundred degrees. If the liquid is squeezed out after some melting has occurred, a melt with a higher silica content results. |
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Term
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Definition
| The theory that proposes that Earth's outer shell consists of individual plates that interact in various ways and thereby produce earthquakes, volcanoes, mountains, and the crust itself. |
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Term
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Definition
| A magnetic field opposite to that which presently exists. |
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Definition
| A mechanism that may contribute to plate motion. It involves the oceanic lithosphere sliding down the oceanic ridge under the pull of gravity. |
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Term
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Definition
| A long, narrow trough bounded by normal faults. It represents a region where divergence is taking place. |
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Term
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Definition
| The hypothesis, first proposed in the 1960s by Harry Hess, which suggested that new oceanic curst is produce at the crests of mid-ocean ridges, which are the sites of divergence. |
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Term
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Definition
| A mechanism that contributes to plate motion in which cool, dense oceanic curst sinks into the mantle and "pulls" the trailing lithosphere along. |
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Term
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Definition
| A long, narrow zone where one lithospheric plate descends beneath another. |
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Term
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Definition
| A large landmass that contains all, or nearly all, of the existing continents. |
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Term
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Definition
| A boundary in which two plates slide past one another without creating or destroying lithosphere. |
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Term
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Definition
| Small space between crust and Upper Mantle with different properties than both. Discovered by Mohorovic. |
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Term
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Definition
| Small space between the Lower Mantle and Outer Core that has different characteristics from both. Discovered by Gutenberg. |
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Term
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Definition
1. Continental Drift
2. Seafloor Spreading |
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Term
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Definition
1. Convergent (towards each other)
2. Divergent (away from each other)
3. Transform (sliding past each other) |
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