The movement caused within a fluid by the tendency of hotter and therefor less desne material to rise, and cooler, denser material to sink under the influence of gravity.
Convection
Closely compacted in substance.
Dense
Type of plate boundary.
Convergent
The gradual movement of continents, through geologic time.
Continental Drift
One giant landmass, 200 million years ago.
Pangaea
The upper layer of the earth's mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur.
Asthenosphere
Type of plate boundary.
Divergent
________ spreading.
Seafloor
A crack, split, or break in something.
Rifts
A long narrow ditch.
Trench
Created the theory that proposed that hot, less dense materialbelow the crust rises toward the surface at the mid-ocean ridges.
Harry Hess
The ridge outer part of the earth, consisting of the crust and upper mantle.
Lithosphere
Hot fluid or semifluid material below or within the earth's crust from which lava and othe igneous rock is formed by cooling.
Magma
Hard inner/outer layer.
Crust
Type of plate boundary.
Transform
A submarine ridge system that extends te length of the Atlantic Ocean from the rtic to the Antarctic.
MidAtlanticRidge
Capable of being attracted by or acquiring the properties of a magnet.
Magnetic
Used to join or strengthen things.
Plate
Created the theory of Continental Drift.
Wegener
Where two plates collide and the denser plate subducts under the less dense plate.
Subduction