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Geography Chapter 12
| Term | Definition |
|---|---|
| Continental Shield | Low-elevation regions of continental crust; various granite cores and ancient mountains are exposed at the surface |
| Terrane | A migrating piece of Earth's crust, dragged about by processes of mantle convection and plate tectonics |
| Folding | The bending and deformation of beds of rock strata subjected to compression forces |
| Anticline | An arch-shaped, upwards fold in which rock strata slope down from the central ridge of the fold |
| Syncline | A trough-shaped downward fold in which the rock strata slope towards the central axis of the fold (think 'sink') |
| Isostacy | A state of equilibrium in Earth's crust formed by the interplay between portions of the less-dense lithosphere and the more-dense asthenosphere and the principal of buoyancy |
| Faulting | The process whereby displacement and fracturing occur between two portions of the Earth's crust; usually associated with seismic activity |
| Normal Fault | A type of geologic fault in rocks. Tension produces strain that breaks a rock, with one side moving vertically relative to the other side along an inclined fault plane |
| Reverse Fault | Compressional forces produce strain that breaks a rock so that one side moves upward relative to the other side |
| Thrust Fault | A reverse fault where the fault plane forms a low angle relative to the horizontal; and overlaying block moves over and underlaying block |
| Slip-Strike Fault | Horizontal movement along a fault line - that is, movement in the same direction as the fault |
| Horst | Upward-faulted blocks produced by pairs or groups of faults [two blocks push a middle one up] |
| Graben | Downward-faulted blocks produced by pairs of groups of faults [two blocks push a middle one down] |
| Orogenesis | The process of mountain building that occurs when large-scale compression leads to deformation and uplift of crust |
| Earthquake | A sharp release of energy that sends waves travelling through Earth's crust at the movement of rupture along a fault or in association with volcanic activity |
| Megathrust Earthquake | The most powerful earthquakes on Earth; occurs along a subduction zone |
| Elastic Rebound Theory | An explanation for how energy is released during an earthquake. Two sides of a fault rupture suddenly due to accumulating stress, snapping to new positions relative to each other |
| Seismometer | An instrument used to detect and record the ground motion during an earthquake |
| Focus | The location below the Earth's surface where the motion of seismic waves that cause an earthquake begins |
| Epicentre | The location on Earth's surface directly above the focus of an earthquake |
| Foreshock | A smaller quake that precedes the main shock of an earthquake |
| Aftershock | Occurs after the main shock, sharing the same general area of the epicentre |
| Richter Scale | An open-ended, logarithmic scale that estimates earthquake amplitude by the energy released, using seismographs |
| Liquefaction | The process whereby ground shaking, usually from an earthquake, disrupts and loosens the structure of the soil, causing it to flow |
| Moment Magnitude Scale | Measures an earthquake by the amount of seismic movement. Considers fault slippage, size of ruptured area, and the nature of the materials faulted |
| Tsunami | A seismic sea wave, travelling at high speeds across the ocean, formed by sudden motion in the seafloor (seismic wave, etc) |
| Volcano | A mountainous landform at the end of a magma conduit, which rises from below the crust and vents to the surface |
| Viscosity | Resistance to flow [thickness] |
| Pyroclastic | An explosively ejected rock fragment launched by a volcanic eruption |
| Pahoehoe | Basaltic lava that is fluid. Forms a thin crust with folds that appear 'ropy', like coiled rope |
| Cinder Cone | A volcanic landform of pyroclastics and volcanic rock, usually small and cone shaped |
| Caldera | An interior sunken portion of a composite volcano's crater; usually steep-sided and circular, sometimes containing a lake |
| Effusive Eruption | A volcanic eruption characterised by lava pouring forth onto the surface, relatively small explosions, and few pyroclastics |
| Shield Volcano | A symmetrical mountain landform built from effusive eruptions; gently sloped and gradually rising from the surrounding landscape to a summit crater |
| Flood Basalts | A type of effusive eruption that occurs when magma flows out from elongated fissures onto the surface and cools into extensive sheets of basaltic lava |
| Explosive Eruptions | A violent and explosive volcanic eruption as a result of thicker, stickier magma |
| Composite Volcano | A volcano formed by a sequence of explosive volcanic eruptions; steep-sided, conical in shape |
Created by:
TheresaH
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