Volcanoes
a weak spot in the crust where magma comes to the surface
volcano
two plates move apart stretches rock
tension stress
two plates slip past each other in the opposite direction; earthquakes usually occur here
transform boundaries
a mixture of molten material, gases and water from the mantle
magma
a tube that connects the magma chamber to the surface
pipe
a pocket beneath a volcano
magma chamber
plates slip apart at an angle
normal fault
changes the surface of the Earth; continental drift
plate movement
bowl-shaped area that may form at the top of a volcano
crater
area covered by lava as it leaves vent
lava flow
currently erupting or showing signs of erupting in the near future
active
can cause rock to break and slip apart or to cange its shape
shearing stress
two plates come together; they collide
convergent boundaries
area where material from the mantle rises, melts, and forms magma which rises to surface forming volanoes
hot spot volcano
crust is pulled together; a type of fault
reverse fault
produce ash and cinders and materials build-up around the vent
cinder cone volcano
a break in the crust causing rock surfaces to slip past each other
faults
two plates move apart
divergent boundaries
lava flows with alternately with eruptions of ash and cinder
coposite volcano
sleeping, but may erupt again sometime in the future
dormant volcano
eruptions empty the magma chamber causing a huge hole as the top of the mountain collapses inward
caldera
movement of the plates create forces that cause rock in the crust to squeeze together or pull apart
stress
along with subduction and sea-floor spreading, this caused Pangea to drift apart
plate movement
dead, unlikely to erupt again
extinct volcano
may erupt in the near future
active volcano