Continental Drift Theory
Alfred Wegener's hypothesis that all continents were once connected in a single large landmass that broke apart approximately 200 million years ago and drifted slowly to their current positions.
(all lands) the name of the single landmass that broke apart 200 million years ago and gave rise to today's continents
The portion of the earth's crust that primarily contains granite, is less dense than oceanic crust, and is 20-50 km thick
the portion of Earth's crust that is usually below the oceans and not associated with continental areas, thinner and higher in density that continental crust and basaltic rather than granitic in composition
thickest layer of the Earth, part "plastic", part solid where convection currents are found
the solid, outer layer of the earth that consists of the crust and the rigid upper part of the mantle
The solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows very slowly, which allows tectonic plates to move on top of it
the force behind plate tectonics; the rise and sinking of warm and cold material
a layer of molten iron and nickel that surrounds the inner core of Earth
a dense sphere of solid iron and nickel at the center of Earth
developed the theory of sea-floor spreading; ocean floors move like conveyor belts, carrying the continents along with them
The process that creates new sea floor as plates move away from each other at the mid-ocean ridges
the process in which Earth's magnetic field, over thousands of years, completely reverses its direction
The theory that explains how large pieces of the lithosphere, called plates, move and change shape
the shaking and trembling that results from the movement of rock beneath Earth's surface
Vibrations that travel through Earth carrying the energy released during an earthquake.
longitudinal waves; 1st, fastest, & go through solids & liquids
transverse waves; 2nd, slower, & go though solids
surface waves; last, slowest; bend & twist crust doing the most damage
a crack in the earth's crust resulting from the displacement of one side with respect to the other
This area is a result of S waves being stopped entirely by the liquid core and P waves being bent (refracted) by the liquid core.
The point beneath Earth's surface where rock breaks under stress and causes an earthquake
the point on the Earth's surface directly above the focus of an earthquake
record of the waves traveling from earthquakes
time between arrival of primary waves and secondary waves at a seismograph station
The measure of the energy that a seismic wave carries
three seismograph stations are required to be able to do this
a logarithmic scale of 1 to 10 used to express the energy released by an earthquake
Richter difference 4-5
An earthquake that has a shaking amplitude 10 times larger
Richter difference 4-6
An earthquake that has a shaking amplitude 100 times larger
A concentration of heat in the mantle capable of producing magma, which rises to Earth's surface; such a location produced the Hawaiian Islands
divergent plate boundary
boundary between tectonic plates in which the two plates move away from each other and new crust is created between them ex: Mid Atlantic Ridge
an undersea mountain chain where new ocean floor is produced; a divergent plate boundary
A deep valley that forms where two plates move apart
convergent plate boundary
A region where plates are pushing together and where a mountain range, island arc, and/or trench will eventually form; often a site of much seismic and volcanic activity.
the process by which oceanic crust sinks beneath a deep ocean trench and back into the mantle at a convergent plate boundary
transform plate boundary
where two tectonic plates slide past each other horizontally ex: San Andreas Fault
location of volcanoes
Most of these occur along plate boundaries or at hot spots in the crust. These can occur along a convergent plate boundary where an oceanic plate is subducted into the mantle. ex: Ring of Fire in Pacific.
dome-shaped volcanoes formed by eruptions of fluid, runny lava; form over hot spots; the largest volcanoes on Earth
cinder cone volcanoes
These volcanoes are built up from ashes, cinders, and rocks that burst from Earth during a violent eruption. The rocks fall back to Earth near the opening to form a cone; most are not taller than 1000 feet.
a tall, cone-shaped mountain in which layers of lava alternate with layers of ash and other volcanic materials