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plate tectonics
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Alfred Wegener-the theory of "continental drift", arguing that all the continents were once joined
together in a single landmass and have drifted apart.. Wegener also speculated on sea-floor
spreading and the role of the mid-ocean ridges
Continental drift hypothesis that continents are in constant motion
plate tectonic-theory that says the Earth’s surface is made up of rigid rock or plates that move with
respect to each other
Pangaea - ancient supercontinent, composed of land that forms today’s continents
Harry Hess- Hess outlined the basics of how seafloor spreading works: molten rock (magma) oozes
up from the Earth's interior along the mid-oceanic ridges, creating new seafloor that spreads away
from the active ridge crest and, eventually, sinks into the deep oceanic trenches.
seafloor spreading - new oceanic crust forms at a mid-ocean ridge as old oceanic crust moves
away
magnetometer-measures the strength and direction of the magnetic fields
magnetosphere- magnetic field around the earth, caused by an imaginary bar magnet in the center of
the earth. ( all the iron )
Ocean plates formed by divergent plate boundaries along mid ocean ridges, where new oceanic
crust is being created. Denser than continental plates
Continental plates formed by convergent plates; oceanic plates subduct under them; magma comes
up, forming new, igneous rock as continental crust.
Lithosphere-rigid outermost layer of earth that includes the uppermost mantle and crust
Asthenosphere-hot solid rock beneath the lithosphere. Causes the plates to move
Mesosphere The lower part of the mantle.
outer core liquid outer core surrounds the inner core, and is believed to be composed of iron mixed with
nickel and trace amounts of lighter elements.
inner core hottest part, is a primarily solid sphere about 1,216 km (760 mi) in radius, only about 70% that of
the Moon. It is believed to consist of an iron-nickel alloy, and may have a temperature similar to the Sun's
surface.
mantle-- middle layer of Earth situated between the crust above and the core below
convection—circulation of materials caused by differences in temperature and density
Convection Currents-Convection currents transfer heat from one place to another by motion
of a fluid such as water, air or molten rock. The heat transfer function of convection
currents drives the earth's ocean currents, atmospheric weather and geology.
list the types of plate boundaries:
a)convergent- plate boundary formed when 2 plates collide ( deep ocean trench and a line of
volcanoes )
b) divergent- plate boundary formed when 2 plates separate ( rift valley ) ( mid ocean ridges )
c)transform- plate boundary formed when 2 plates slide past each other ( earthquakes)
fault –break or crack in rock caused by stress and pressure
subduction zone-process by which a more dense plate sinks below a more buoyant plate
San Andreas Fault-continental transform fault that is roughly 810 miles (1,300 km) through
California. The fault's motion is (horizontal motion). It forms the tectonic boundary between the
Pacific Plate and the North American Plate.
Mid ocean ridge -mountain range located on the seafloor in the middle of the ocean
Great rift valley- formed at divergent plate boundaries
Himalayas-folded mtns. formed at convergent boundaries of plates. No volcanoes formed as no
subduction zone
Island arcs- volcanic arc--formed as one oceanic tectonic plate subducts under another one
and, in most cases, produces magma below the plate above it. Result of friction between
converging plates !
Glomar challenger-a deep sea research and scientific drilling vessel for oceanography and marine
geology studies. It cris-crossed the Mid-Atlantic Ridge between South America and Africa and
drilled core samples at specific locations. When the age of the samples was determined by
paleontologic and isotopic dating studies, conclusive evidence for the seafloor spreading
hypothesis, and, consequently, for plate tectonics was provided !
Sonar- Used to create a topographic map of the ocean floor, due to different sound levels due
to different densities. SOund Navigation And Ranging) is a technique that uses sound propagation
(usually underwater, as in submarine navigation) to navigate, communicate with or detect objects on
or under the surface of the water, such as other vessels.
Tsunami-huge tidal wave often caused by a severe earthquake.
North American Plate-The North American Plate is a tectonic plate covering most of North
America, Greenland, Cuba, Bahamas, and parts of Siberia, Iceland and the Azores.
Marianas Trench -the deepest part of the world's oceans. It is located in the western Pacific
Ocean, to the east of the Mariana Islands. about (1,580 mi) long , average width of only
(43 mi). It reaches a maximum-known depth of 10.911 km or 6.831 mi although some unrepeated
measurements place the deepest portion at 11.03 kilometres (6.85 mi)
Hot Spots-volcanic regions thought to be fed by underlying mantle that is extremely hot compared
with the mantle elsewhere. They may be on, near to, or far from tectonic plate boundaries.
Hawaiian islands are hot spots.