Download Unit Vocab

Layers of the Earth
Crust: land layer made up of rock and soil that we
walk on (thinnest layer)
Lithosphere: bottom portion of the crust and the
upper mantle
Upper Mantle: layer of pliable rock just below the
crust where earthquake movement occurs
Deep Mantle: thickest layer just below the upper
mantle
Outer Core: made of molten rock and metals just
above the inner core
Inner Core: solid center made of heavy metals;
hottest layer
Hydrosphere: all the water on Earth
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Convection currents: caused by very hot material
at the deepest part of the mantle rising, then
cooling and sinking again; repeats this cycle
Asthenosphere: heat deep inside the Earth that
drives the movement of the Earth’s plates nearer
the surface, located in the middle mantle
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Continental Drift
Geologist: scientist who studies the Earth
Continental Drift: theory presented by Wegener;
stated that continents were once one big supercontinent that drifted apart over many years to
their present-day locations
Pangaea: name given to the super-continent
Mid-Atlantic Ridge: ridge in the Atlantic Ocean
through which molten rock flows
Sea-Floor Spreading: process where new crustal
material forms at the ridges causing the old sea
floor to spread apart on both sides of the ridge
Magma: molten rock underground (called lava
when on the surface of the Earth)
Plate Tectonics
Plate Tectonics: theory that the Earth’s crust is
broken into pieces or plates; each plate includes
material from a layer below the crust (mantle);
plates slide on the lower portion of the mantle
Divergent Boundary: places where the plates
move apart (Mid-Atlantic Ridge)
Convergent Boundary: places where the plates
collide (Himalayan Mountains)
Transform Boundary: places where plates slide
horizontally past each other
Faults
Fault: cracks in the Earth’s crust caused by the
movement of plates
Normal Fault: 2 sides pull apart and 1 side falls
below the other
Reverse Fault: 2 sides push together and 1 side
rises up over the other
Strike-slip Fault: 2 sides slide horizontally past
each other
 New Madrid is the fault closest to us;
combination of a strike-slip and reverse
Parts of an Earthquake
Focus: point below the Earth’s surface where the
earthquake starts
Epicenter: point on Earth’s surface directly above the
focus
Surface Waves: waves that travel across surface of
Earth and tear apart structures; can move side to side
or up and down (Most destructive)
Seismic Waves: vibrations from the sudden movement
that travels through the crust; 2 types of waves
P Waves: primary waves; travel like an accordion
S Waves: secondary waves; travel like a twanged fork
(slower)
Aftershock(s): tremors/shaking after the earthquake
occurs
Seismograph: instrument used to measure the strength
of an earthquake
Tsunami: huge ocean wave caused by an earthquake
Measuring Strength of an Earthquake
Magnitude: amount of energy released by an
earthquake
Richter Scale: scale from 1 to 10 that ranks
earthquakes according to magnitude (uses
seismograph); for every unit increase the energy
released is increased by a factor of 30
Mercalli Scale: scale from 1 to 12 (in Roman
Numerals) that describes earthquakes based upon
the amount of damage
Volcanoes
Volcano: an opening in the Earth’s crust from
which hot molten rock moves from deep inside
the Earth
Ring of Fire: edges of Pacific Plate where many
earthquakes and volcanoes occur
 Most volcanoes occur along plate boundaries
 Volcanoes can
o Create new land
o Create fertile soil
Types of Volcanoes
Shield Volcano: wide, flat mound created because
lava from volcano is not as thick (viscous) and
doesn’t clog up
Cinder-Cone Volcano: has steep-sided cone
created from volcanic explosion of thick magma
that bursts free
Composite Cone: symmetrical shaped cone;
eruption may explode then have flowing lava;
explosion “takes turns” between shield and
cinder-cone type explosions
Formation of Volcanoes
Subduction Volcano: formed when one plate falls
below the other (Mt. St. Helens & Mt. Vesuvius)
Rift Volcano: formed when two plates pull apart
(African Rift Valley)
Hot-Spot Volcano: formed when magma melts a
hole through the middle of a plate (Hawaiian
Islands)
Parts of a Volcano
Magma: hot, molten rock inside the Earth
Lava: molten rock on the Earth’s surface
Crater: major vent at the top of the volcano
Conduit: path from magma chamber to crater
Cone: the volcano, formed by volcanic material
Magma Chamber: stores molten rock
Dike: vertical crack that holds harden magma
Sill: horizontal crack that holds harden magma
Fissure: long, thin fracture out to the side of the
conduit
More on Volcanoes
Dormant: French word for “sleep,” a dormant
volcano has not been active for a long time, but
erupted in recorded history
Extinct: has not erupted in recorded history
Side effects of volcanoesGeyser: an opening in the ground through
which hot water and steam erupts periodically
Hot Springs: an opening in the ground where
hot water and gases escape continually, but
not erupt
Geothermal Energy: heat from below the
Earth’s surface; produces steam to run power
plants that provide electricity