Transcript The Theory of Plate Tectonics

The Theory of Plate Tectonics
Plate Tectonics
• Became a theory in the 1960’s
• Describes plate movements AND explains
why they move
Plate Tectonics
• Two types of crust:
Oceanic and
Continental
• Plates are usually
made of both types
• Plates: Chunks of
lithosphere
“floating” around on
the asthenosphere
• Earthquake data and volcanoes are used
to find the boundaries of the plate
boundaries.
Plate Boundaries
• Three Types:
• Divergent Boundaries: plate are moving
away from each other
• Plates move apart, molten rock from
asthenosphere fills gap
Plate Boundaries
• Most found on the ocean floor (mid-ocean
ridges)
• Rift valley: valley in the center of the midocean ridge
Plate Boundaries
• volcanoes and earthquakes occur at
divergent plate boundaries
divergent boundaries
Where is this happening at?
MidAtlantic
Ridge
East Pacific Rise
• Iceland
The Red Sea
Divergent boundaries