Continental Drift & Plate Tectonics
Text Book Chapter
Resources from the State of Texas
Vocabulary
Asthenosphere
Layer of earth right below the lithosphere. This is the layer on which the tectonic plates "float"
Crust
The thinnest layer of the earth made of rock, on Earth's surface
Continental Drift
The hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations.
Convection Currents
A convection current is a process which involves the movement of heat energy from one place to another. Warm fluid rises up because of decreased density and cool fluid sinks because of increased density. They create circular motion that moves the tectonic plates.
Convergent Boundary
The type of boundary that forms when two tectonic plates collide.
Divergent Boundary
The type of boundary that forms when two tectonic plates divide and move away from each other
Fault
A crack in the earth's crust resulting from two tectonic plates sliding past one another
Folded Mountains
Formed when two tectonic plates collide and push earth upwards
Lithosphere
The rigid layer of the earth consisting of the crust and upper mantle.
Mantle
The layer of earth between the crust and the core
Pangaea
A supercontinent containing all of Earth's land that existed about 225 million years ago.
Rift Valley
A deep valley that forms where two continental plates move apart.
Seafloor Spreading
process that creates new ocean floor at mid-ocean ridges and destroys older crust at deep sea trenches
Subduction
Process in which one plate moves under another plate, and into the mantle. Takes place at a convergent boundary.
Subduction Zone
area where seafloor goes back into the mantle
Theory of Plate Tectonics
The theory that explains how large pieces of the lithosphere, called plates, move and change shape constantly.
Transform Boundary
The type of boundary that forms when two tectonic plates slide past one another
Alfred Wegener
the man who investigated continental drift after finding fossils on opposite sides of oceans.