Study Guide for Plate Tectonics

Continental Drift Theory
Theory that states that the continents were once together; broke appart and moved to their present day locations.
Theory of Seafloor Spreading
Mid-ocean ridge is a crack in the Earth’s crust through which molton rock rises to the surface, adding new material to the ocean floor.
Theory of Plate Tectonics
States that Earth’s lithosphere (crust) broke up into moving plates.
What is the evidence for the Continental Drift?
Jigsaw fit between South America and Africa, Rock and mountain types on both coasts match, Climate clues, Similar fossils on both coasts.
Pangaea
“All Land”; a large, single, land mass made up of all the continents.
How long ago did Pangaea exist?
300 Million years ago.
Relationship between Rift Valleys and the MOR.
Rift valleys and Mid-Ocean Ridges are both places where new materials/ocean floor is being created.
Crust
Outermost layer of the earth, low density
Ocean floor
basalt; 6km thick; more dense than crust
Continents
granite; 20-70km thick; less dense than the crust
Mantle
layer surrounding the core
Asthenosphere
upper solid portion that moves like liquid
Core
innermost layer of Earth
Outer Core
2000km thick; liquid iron
Inner Core
1500km radius; solid mixture of iron, nickel and cobalt
Moho
Boundary between mantle and crust
Lithosphere
made up of the crust and rigid upper mantle
Asthenosphere
Upper, solid portion that moves like liquid
Appalachians
Stretch from eastern USA to the Gulf of Mexico; created when N. America collided with Africa.
Himalayas
Along the borders of Tibet and India; formed when India collided with Asia.
7 Major Plates
Indian-Australian, Philippine, Juan de Fuca, Cocos, Pacific, Nazca, Antarctic, South American, Caribbean, North American, Eurasian, Arabian, African
Transform Fault
Two divergent plate boundaries are sliding past eachother
Divergent Boundaries
Sites where two plates are moving apart
Convergent Boundaries
Place where plates (continental, oceanic) are moving together forming trenches, island arcs, and folded mountains
Subduction
A place where 2 plates collide and 1 plate is pushed below the other one. Happens in a subduction zone.