plate tectonics Flashcards
crust
the outermost shell of a rocky planet
mantle
layer of molten rock between the crust and core
core
made up of mostly iron. outer core (molten) and inner core (solid)
tectonic plate
the layer of rock that makes up the outer part of the earth, including the crust and upper mantle lithospheric plates
continental drift theory
the theory that continents gradually drifted over time to their present positions
asthenosphere
a thin layer of earth, about 150 miles thick at the border between the mantle and the crust
convection current
the process in which the hotter parts of a gas or liquid rise to the top and the cooler denser parts sink.
convergent boundary
when two tectonic
mountains
uplift of crustal plates that form elevated landmasses
volcanoes
a vent or fissure in earths surface through which magma and gases are expelled
divergent boundary
when tectonic plates split apart.
transform boundary
when tectonic plates slide past each other
fault
breaks in the crust. the movement which produces earthquakes
mid-ocean ridge
a long ridge of underwater volcanoes between two diverging oceanic plates.
subduction zone
a place where one tectonic plate sinks under another and melts. also forms a trench