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29 Cards in this Set
- Front
- Back
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Counter-balancing forces w/in Earth
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1) Mountain building
2) Erosion and transportation of sediment |
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Typical Mtn. Volume
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V(mtn)= length x height x width
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Rate of mtn. erosion
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150 m^3/yr
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Volcanoes
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belts where molten rock (magma) form the upper mantle or lower crust come to the surface (lava)
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Earthquakes
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belts where there are planes of weakness and breakage in brittle crustal rocks; site for potential energy conversion mechanical energy or tsunami
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Plate Movement
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physical displacemnet of great segments of the Earth's crust; can be directly measured using GPS and other technology
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Plate Tectonics
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Concept that the crust of the Earth is broken up into several (~15) large plates (tectonic plates), as well as several smaller ones
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Mantle Convection
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Driving force of plate tectonics. Drags plates along and keeps them moving
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ocean floors
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contain volcanic mountain ranges and spreading center tha demonstrate how the ocean floor is formed at mid-ocean ridges and moves away gradually from these ridges
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record of magnetic reversals
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- magnetized rock on the ocean floor (basalt) forms a record of earth's magnetic field when cooled
- patterns of magnetization on the sea floor are parallel zones on opposite sidees of mid-ocean ridge |
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Curie temperature
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the temp at which a crystal containing Fe acquires magnetization after forming from a liquid
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Plate travel time
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T(plate)= D(plate)/Speed(plate)
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Pangaea
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supercontinent comprised of all land mass that existed about 250 to 140 million years ago
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Divergent plate boundaries
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new plate material (rock) is formed here; site of volcanism, shallow low-magniture earthquakes
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Convergent plate boundaries
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plates come together at a rate of a few cm/yr
- crust buckles up to form folded mountain chains (orogeny) - sea floor crust ois taken back into earth - volcanoes form from melting during subduction - great earthquakes occur due to break up of subducting crust - ocean trenches form as a result of subduction |
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Transform plate boundaries
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- where plates glide past one another along a great crustal fault zone
- powerful earthquakes, but no volcanoes |
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Volcanoes and plate boundaries: divergent
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basaltic (silica-poor) volcanoes that erupt large quantities of lava (non-violent)
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Volcanoes and plate boundaries: convergent
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silica-rich volcanoes; magma due to melting of subduction plate (violent eruptions)
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Volcanoes and plate boundaries: hot spots
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local (intra-plate) sites on Earth where plumes of hot, liquid mantle rise and melt through the crust forming huge volcanoes; independent of plate boundaries
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Earthquakes and plate boundaries: focus
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site of initial earthquake motion in the earth's crust
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Earthquakes and plate boundaries: epicenter
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map location on the surface above the focus
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Earthquakes and plate boundaries: divergent
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shallow focus (<10 km) and rather weak
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Earthquakes and plate boundaries: convergent
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shallow to deep focus (down to 200 km, deepest earthquakes occur) dues to subduction plate breaking up (shallow more common than deep)
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Earthquakes and plate boundaries: transform
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shallow focus earthquakes that are potentially very powerful if the earthquakes rare, but rather weak if they occur all the time
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Earthquakes and plate boundaries: hot spots
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shallow focus only; weak but frequent
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Seismology
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study of earthquake vibrations and what they can tell us about the earth itself
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Wave types
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- P-waves (compressional or longitudinal waves)(sound)
- S-waves (transverse waves)(shaking) |
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P-waves
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- waves in which molecules move back and forth in the same direction as the wave moves
- fast waves that travel several km/sec in through solid rock, liquid and gases |
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S-waves
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waves in which molecules move up and down perpindicular to the direction of wave motion; slow waves that cannot pass through a liquid or gas (only solid rock)
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