What is the Theory of Plate Tectonics? • It states that pieces of Earth’s lithosphere are in a slow, constant motion, driven by convection currents in the mantle. • As the plates move, they collide, pull apart, or grind past each other, producing spectacular changes in

Earth’s surface. These http://w3.salemstate.edu/~lhanson/gls110/GLS110_BasicConcepts.htm changes include volcanoes, mountain ranges, and deep ocean trenches.

Plate Boundaries • The places where these lithospheric plates come together are called plate boundaries • There are three types: divergent boundaries, convergent boundaries, and transform boundaries. • A different type of plate movement occurs along each type of boundary.

What is a divergent boundary? • Divergent Boundary: where two plates move apart

What happens at divergent boundaries? • #1. If two oceanic plates move apart, then a mid- ocean ridge is formed. EX: Atlantic Mid-Ocean Ridge

• #2. If two continental plates move apart, then a rift valley is formed. EX: Great Rift Valley in Africa This happens because… • Molten material fills in the space left between the two plates to form new land. We can see this above water in Iceland!

Hydrotherma vents along mid- ocean ridges! Smokers

Can things live in this superheated environment? Complex communities fueled by the chemicals dissolved in the vent fluids

Tubeworms, palmworms, scale worms and limpets thrive in warm, diffusely flowing vent fluids issuing from the black smoker chimney "Finn" on the Juan de Fuca Ridge What is a convergent boundary?

• Convergent boundary: place where two plates come together. • The result is a collision where the density of the plate

determines what http://www.divediscover.whoi.edu/images/tectonics-collide.jpg happens. Convergent Boundary #1

• If an oceanic plate meets a continental plate then the oceanic plate is subducted and volcanoes are formed. • This happens because the oceanic plate is more dense. Convergent Boundary #2

• If two continental plates collide (equal density), mountains are created. • EX: Himalayas

Convergent Boundary #3 • If two oceanic plates collide then the plate that is more dense will subduct into the mantle through a deep-ocean trench. What is a transform boundary?

• A boundary where two plates grind past each other without the production or destruction of lithosphere. • A fault is created. EX: San Andreas Fault

• Notice subduction zone…

When it comes to the Earth, it’s like a rug…

http://rst.gsfc.nasa.gov/Sect2/Sect2_6.html

• Over millions of years, the forces of plate movement can change a flat plain into landforms such as anticlines and synclines, folded mountains, fault-block mountains, and plateaus. Folding Earth’s Crust

• This results in mountains and plateaus. EX: Colorado Plateau

Rockies were never volcanoes. Divergent Convergent Transform