Unit 7 Vocabulary Evidence for Plate Tectonics & the Formation of

 Unit 7 Vocabulary
Evidence for Plate Tectonics & the Formation of Crustal Features
Pangaea - a supercontinent that existed 225-260 million years ago. A large landmass formed
by all the continents coming together. Greek origin meaning “all lands”.
theory of plate tectonics - states that the Earth is made up of several rigid plates that
move on the asthenosphere.
continental drift - a theory stating that the Earth's continents have been joined together
and have moved away from each other at different times in the Earth's history.
sea floor spreading - a process in which new ocean floor is created as molten material from
the earth's mantle rises in margins between plates or ridges and spreads out.
convection currents – currents caused by the expansion of a liquid, solid, or gas as
temperature rises.
subsidence – a lowering in the elevation of land.
boundary - something that points out or shows a limit or end : dividing line.
plate boundary – region where 2 plates meet.
convergent boundary - areas where plates move toward each other and collide.
divergent boundary - areas where plates move away from each other.
transform boundary - occurs when two plates grind past each other.
rift - an opening made by splitting or separation.
ridge - a raised or elevated part or area.
trench – a deep depression of the sea floor caused by the subduction of one plate under
another (convergent).
fault – a break or crack in the Earth’s surface.
theory – an idea that is the best explanation of many observations and helps make new
subduction zone – where oceanic plates meet a continental plate and is pushed underneath
(type of convergent boundary).