Download Ch 12 Vocabulary - Taylor County Schools

Ch 12 Vocabulary
Mid-Ocean Ridge (MOR) –
Continuous system of twin
mountain ranges with a rift valley
between them that extends around
Earth on the seafloor. Formed at a
divergent plate boundary.
Rift Valley – Long, linear,
dropped-down valley between
twin, parallel mountain ranges
produced by faulting.
Divergent Boundary – Plate
boundary where the plates are
moving away from each other.
Convergent Boundary – Plate
boundary where the plates are
moving toward each other.
Subduction – Occurs when
lithospheric plates converge and
the edge of one plate is forced
downward beneath another.
Transform Boundary – Plate
boundary where the plates are
moving laterally to each other (one
in one direction and the other in
the opposite direction).
Fault – crack in Earth’s crust
along which movement has taken
place
Focus – Point of origin of an
earthquake
P-waves – Primary waves. The
first and the fastest wave to get to
the surface of the Earth during an
earthquake.
S-waves – Secondary waves. The
second wave to reach the surface
of the Earth.
Epicenter – Location directly
above the focus where the waves of
an earthquake first meet the
surface the Earth.
Shadow zone – “Dead zone”
between 105 and 140 degrees from
an earthquake’s epicenter where
nothing is recorded on a
seismogram.
Asthenosphere – The lower
mantle.
Lithosphere – The crust and the
upper mantle.
Viscosity – A fluid’s resistance to
flow.
Cinder cone volcano – Small,
violently erupting volcano formed
by accumulation of large
pyroclastic materials around a
vent.
Shield volcano – Broad, flat
volcano formed by layers of freeflowing, high-temperature, basaltic
lava.
Composite volcano – Volcano
formed by alternating lava flows
and violently erupting pyroclastic
materials.
Hot spot – Volcanically active sites
that arises in the middle of a
tectonic plate. Hot spots do not
move.
Pyroclasts – Material expelled
from a volcano that cools and
becomes solid as it falls to Earth.
Volcanic blocks – Chunks of solid
material ripped away from the
opening of the volcano and
expelled into the air.
Lahar – Volcanic Mudflow