Daily Review #1

Warm UpWhat is a convection current?How does convection cause a lithospheric plate to move?

Times Up!Volcanic Boundaries

ConvergentBoundaryPlates collideContinental-continentalCreate mountainsContinental-oceanicOceanic sinksSubduction zone and trenchRemelted, recycledOceanic-oceanicOne subducts3 types of convergent boundaries based on types of crust of colliding platesContinental continental: example = India into Eurasian plate, a plate will subduct, but other buckles upward forming mountain ranges; creating the Himalayas todayContinental oceanic: example = Pacific and North American plates in places, creates a subduction zone and trench as ocean crust sinks because it is more dense, oceanic crust is melted and recycled in the mantle, can also create volcanoesOceanic and oceanic: example = Pacific and Australian plates, one of them subducts

3Convergent BoundariesSubductionOceanic subductedProduces magmaMagma rises to form volcano

4- As rock subducts subjected to higher temperature and pressure, releases water from crust, mixes with rock, lowers melting point, causing it to form magmaExplosive EruptionsRareDestructiveProduce clouds ofDebrisAshGas

5Ash molten rock blown into dust-sized particles that harden in the airCan blast millions of tons of lava and rock in a single explosion in seconds

6Pyroclastic FlowsProduced in small amounts of time, large amounts of materialLahar = volcanic mud flowFaster than a hurricaneTemperatures greater than 700 deg. CelsiusDeadly

7

Divergent BoundariesRift zoneFilled by magmaMid-ocean ridgesMost volcanic activityIceland, island of Surtsey8Rift zone = deep cracks between separating platesMagma fills rift cracks due to lower density it rises up, cools and forms new crust

Nonexplosive EruptionsMost commonProduceCalm lava flowsHuge amounts of lavaShape our worldIslands in the PacificSea floorNW U.S.

9