The soft layer of the mantle on which the tectonic plates move
Back
Pyroclast
Front
fragment of rock formed by volcanic explosion
Back
seafloor spreading
Front
The process that creates new sea floor as plates move away from each other at the mid-ocean ridges
Back
plate tectonics
Front
The theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle.
Back
crater
Front
A bowl-shaped area that forms around a volcano's central opening
Back
Magma
Front
Molten rock beneath the earth's surface
Back
The angle of repose
Front
the steepest angle at which loose material remains stationary without sliding downslope
Back
ash cloud
Front
a cloud of ash that forms in the air after some volcanic eruptions
Back
pyroclastic flow
Front
the flow of ash, cinders, bombs, and gases down the side of a volcano during an explosive eruption
Back
Main Vent
Front
the weak point in the
Earth's crust where hot magma rises
from the magma chamber and reaches
the surface.
Back
volcanic bombs
Front
A projectile of hot magma or rock that is blown from the vent during a volcanic eruption. These solidify in flight and frequently form an elongated rock of streamlined shape.
Back
Secondary vent
Front
Magma can reach the surface in other areas
Back
convection current
Front
the movement of a fluid, caused by differences in temperature, that transfers heat from one part of the fluid to another
Back
magma chamber
Front
the pocket beneath a volcano where magma collects
Back
Continental Drift Theory
Front
the idea that continents slowly shift their positions due to movement of the tectonic plates on which they ride
Back
Caldera
Front
a large crater caused by the violent explosion of a volcano that collapses into a depression
Back
Lava
Front
Magma that reaches Earth's surface
Back
Lithosphere
Front
the rigid outer part of the earth, consisting of the crust and upper mantle.