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Unit 3 Vocab
Plate tectonics
Term | Definition |
---|---|
Asthenosphere | The upper mantle (one of Earth's layers) |
Subduction | When two plates collide, the less denser plate eventually descends below the other |
Seafloor Spreading | The theory that explains how new oceanic crust formed at ocean-ridges, slowly moved away from ocean ridges, and destroyed at deep sea trenches |
Mantle convection | The driving mechanism of plate movements (cooler mantle sinks, warmer mantle rises) |
Ridge push | When older seafloor sinks, the weight of the uplifted ridge is thought to push the oceanic plate towards the trench formed at the subduction zone |
Slab pull | The weight of the cool, dense subducting plate pulls the trailing slab into the subduction zone |
Lava | Magma that flows out onto the Earth's surface |
Magma | Molten material that forms and accumulates beneath the Earth's surface |
Tectonic Plate | Huge pieces of crust and rigid upper mantle that fit together at their edges to cover the Earth's surface |
Theory of continental drift | Alfred Wegener's hypothesis that all of the continents were all together at one point (a.k.a. Pangaea) |
Convergent Boundary | Two tectonic plates colliding towards each other |
Divergent Boundary | Regions where two tectonic plates move apart |
Transform Boundary | A region where two tectonic plates slide horizontally past each other |
Hot spot | A region of heated magma in the mantle below |
Epicenter | The point on Earth's surface directly above the focus |
Focus | The point of failure where the first body waves originate |
Pangaea | All of the continents fitting together like a puzzle piece |
Geohazard | Environmental problems that can cause a lot of damage |
Reverse Fault | Upward vertical movement along a fault plane caused by compression |
Normal Fault | Downward vertical movement along a fault plane caused by tension |
Strike-slip Fault | Horizontal movement along a fault plane caused by shear |
Compression | Stress that decreases the volume of a material |
Tension | Stress that pulls the material apart |
Shearing | Stress that causes material to twist |
Felsic | Igneous rocks (Granite rocks) that are light colored rocks and have high silica components, and contain mostly quartz and feldspar |
Mafic | Igneous rocks (Basaltic rocks) that are dark colored and have low silica contents, and contain mostly plagiocase and pyroxene |