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98 Cards in this Set
- Front
- Back
the study of the historical changes of shapes and positions of the continents and oceans
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paleogeography
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how many large tectonic plates are there
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13
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fault where plates slide past each other
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transform boundary
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rock is neither created nor destroyed at this boundary
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transform boundary
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where and why do transform faults form
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near spreading centers to accomodate plate's shape change
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extension of transform fault that is no longer active
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fracture zone
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rare example of transform fault on land
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San Andreas Fault
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boundary where plates come together
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convergent boundary
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process of the heavier plate sliding under the lighter one
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subduction
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trenches are formed by what plate process
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subduction
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deepest trench
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Mariana Trench
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deepest part of Mariana Trench; how deep
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Challenger Deep; 11 km
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longest trench; how long
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Peru-Chile trench; 5,900 km
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fragments of basaltic oceanic lithosphere embedded in continents by obduction
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ophiolites
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process by which oceanic crust is deposited in continental crust during subduction
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obduction
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boundary where plates move apart
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divergent boundary
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axis of divergent boundary and sea-floor spreading
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spreading center
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circulation in the mantle that pushes up the lithosphere and causes a divergent boundary
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convection current
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where are hydrothermal vents found
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mid-ocean ridges and rises
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longest mid-ocean ridge
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Mid-Atlantic Ridge
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fastest-spreading oceanic rise; spreading rate
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East Pacific Rise; 13-16 cm/yr
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depression along the middle of a mid-ocean ridge
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rift valley
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length of global ridge/rise system
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75,000 km
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how is an oceanic rise different from an oceanic ridge
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faster spreading, smoother, shorter, wider, less steep
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where does the Mid-Atlantic ridge come above sea level
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Iceland and the Ascension Islands (south Atlantic)
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places where superheated water exits from the sea floor after being heated by magma deep beneath the surface
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hydrothermal vents
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why doesn't water coming from hydrothermal vents boil
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high pressure
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where are the only active hydrothermal vents in US waters
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Oregon coast
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3 types of hydrothermal vent
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warm-water vent, white smoker, black smoker
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chemical responsible for whiteness of a white smoker
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barium sulfide
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temperature range of white smoker
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30-350 C
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a black smoker spews what black chemicals; pH range; temperature range
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metal sulfides and hydrogen sulfide; pH: 3-4; above 350 C
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shallowest hydrothermal vent field found along the Mid-Atlantic ridge
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Lucky Strike
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places where water comes out of the sea floor but is not hot
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seeps
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2 types of seeps
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hydrocarbon seeps, hypersaline seeps
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large volume of warm, grey/black, mineral-rich, low-density water that may occur due to an eruption of an underwater volcano or because of a large quantity of active hydrothermal vents
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megaplume
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active or passive margin: US Pacific shore; US Atlantic shore
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active; passive
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wide continental margin with no tectonic activity and lots of sediment
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passive margin
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thin, steep-sloped continental margin with high tectonic activity (including volcanoes & earthquakes)
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active margin
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chain of islands formed when subducting lithospheric plate increases pressure on magma, causing volcanoes to pop out of the crust in a line parallel to a convergent boundary
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island arc
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2 examples of island arcs
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Mariana islands, Aleutian islands
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Indonesian volcano that exploded in 1883 and is still the strongest explosion ever recorded
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Krakatau
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a volcanic mountain that is more than 1 km tall but does not break the surface of the water
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seamount
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a flat-topped seamount that has been eroded by wave action at the surface
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guyot [tablemount]
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small elevated protusion of the crust under 1 km tall
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abyssal hill [seaknoll]
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area with many seaknolls
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abyssal hill province
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locations that have active volcanoes for a long time
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hotspot
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narrow vertical convective streams of upwelling magma from deep in the mantle that may cause hotspots
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mantle plumes
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chain of islands formed as a plate passes over a hotspot
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nematath
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2 examples of nemataths
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Galapagos islands, Hawaiian islands
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what country owns the Galapagos islands
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Ecuador
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broad area of great volcanic action and high heat flow in French Polynesia around a hotspot
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Superswell
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dark igneous rock formed at convergent subductive boundaries above the continental plate that is an intermediate between basalt and granite
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andesite
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gray or black rock that composes islands and marine volcanoes
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basalt
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smooth pillow-shaped basalt rocks that form when lava cools quickly underwater
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pillow lava / pillow basalt
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newer scale used by the USGS to measure medium and large earthquakes
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moment magnitude scale
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older logarithmic scale used to measure small earthquakes
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Richter scale
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thicker lithosphere results in _________ earthquakes
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stronger
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deep, seismically-active zone on a subductive plate caused by the bending and extending of oceanic crust deep below the surface
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Benioff zone
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2 fast types of seismic waves
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pressure/primary waves, shear/secondary wave
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waveform of: pressure wave; shear wave
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longitudinal, transverse
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type of seismic wave that doesn't travel through liquids
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shear wave
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methodology for estimating the Earth's inner properties
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seismic tomography
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explosive is detonated underwater and the characteristics of the reflected seismic waves are measured and recorded
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seismic profiling
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point at which an earthquake originates
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focus
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point directly above an earthquake’s focus on the Earth’s surface
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epicenter
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area of divergence on land
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rift
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raised section of a rift; depressed section of a rift
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horst; graben
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theory that continents move across Earth’s surface
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continental drift
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contiental drift was proposed by who; when
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Alfred Wegener; 1915
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how long ago did Pangaea, the supercontinent, exist
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225 million years ago
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ocean surrounding Pangaea that was the precursor to the Pacific ocean
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Panthalassa
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what does Pangaea mean in ancient Greek
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all the land
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2 continental pieces that formed after Pangaea broke up
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Laurasia (north), Gondwanaland (south)
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sea separating Laurasia and Gondwanaland that was the precursor to the Mediterranean Sea
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Tethys Sea
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who proposed mantle convection as the cause for seafloor spreading; when
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Harry Hess; 1962
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what is the cause of convection currents and temperature differences in the mantle
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radioactivity
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on average, how long does it take oceanic crust to be recycled
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110 million years
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age of oldest rocks: in the ocean; on land
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180 million years; 3.8 billion years
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range of average relative speeds of tectonic plates
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2-12 cm/yr
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the balance of Earth's internal pressures and maintenance of buoyancy
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isostasy
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movement of a tectonic plate to balance pressures
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isostatic adjustment
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who found and explained magnetic anomalies along spreading centers
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Frederick Vine
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succession of projects created to obtain geological data from the ocean floor
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Deep Sea Drilling Project (1968), Ocean Drilling Program (1985), Integrated Ocean Drilling Program (2004)
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the growth of a continent as it accumulates pieces of other continents, islands, and volcanoes
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continental accretion
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a group of islands
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archipelago
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offshore area along California where transform faults result in unusual basins and islands
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continental borderland
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small island that just recently appeared near Iceland
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Surtsey
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newest volcano in the Hawaiian island chain still below the surface
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Loihi
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island group in the Caribbean including Cuba
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Antilles
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tallest mountain measured from its base
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Mauna Kea
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tallest active volcano measured from its base
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Mauna Loa
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which ocean is shrinking; growing
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Pacific ocean; Atlantic ocean
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volcanoes and trenches around the edges of the Pacific Ocean due to convergence
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Ring of Fire
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loop of andesite formations around the Pacific Ocean
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andesite line
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life cycle of ocean basins as they are changed by tectonic processes
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Wilson cycle
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6 stages of the Wilson cycle from first to last
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embryonic, juvenile, mature, declining, terminal, suturing
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column of minerals deposited by a hydrothermal vent
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chimney
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