4.1 Plate Tetonics

Core

Dense mass of solid nickel, iron, and radioactive elements that release massive amounts of heat

Mantle

Liquid layer of magma surronding core, kept liquified by intense heat from the core (viscous)

Asthenosphere

(not real layer of the earth)

Viscous, flexible outer layer of mante, beneath the lithosphere

Lithosphere

thin, brittle layer of rock floating on top of the mantle (broken up into tetonic plates)

Crust

very outer layer of lithosphere, earths surface

Divergent Plate Boundary

• Plate moving away from each other

• rising magma from mantle push apart

Divergent Plate Boundaries Form

mid-oceanic ridges, volcanoes, seafloor spreading, and rift valleys

Convergent Plate Boundaries

• Plates move toward eachother

• leads to subduction (one plate being forced beneath the another)

• the denser plate allow subducts (ocean)

Convergent Plate Boundaries Form

mountains, island arches, earthquakes, and volcanoes

Transform Plate Boundaries

• Plate slides past eachother in opposite direction

• Forms = earthquakes

Convection Cycles: Step 1

• magma heated by the core rises towards lithosphere

Convection Cycles: Step 2

• rising magma cools and expands, forcing oceanic plates apart

Convection Cycles: Step 3

• magma cool and solidifies into new lithosphere

Convection Cycles: Step 4

Spreading magma forces oceanic plate into continent (subduction plate)

• sinking oceanic plate melts back into magma

• also forces magma up, creating narrow coastal mountains (Andes) and volcanoes on land

Oceanic - Oceanic Zone

one plate subducts under the other

• forces magma up

• forms mid oceanic ridges, island arches, and off shore trenches

Oceanic - Continental Zone

oceanic plate will subduct, plate melts back into magma

• forces magma up

• Forms coastal moutains, volcanoes on land, tsunamis, and trenches

Continental - Continental Zone

One plate subducts underneath other, forcing surface crust upward

• forms mountains (Himilayas)

Transform Fault Boundary

plate sliding past eachother in opposite direction create a fault (fracture in rock structure)

• occurs when rough edges of plates get stuck on eachother

• pressure builds up as plates keep sliding, but stay stuck

• release energy that shakes the lithosphere

San Andreas Fault - California plate boundary

Ring of Fire

most tectonically active place in world

• pattern of volcanoes all around pacific plate

• offshore island arc (japan)

Transform Faults

likely location of earthquakes

Hotspots

areas of espically hot magma rising up to lithosphere

• mid-ocean islands (Iceland + Hawaii)