Geology- Plate Tectonics

What was the first theory that related to Plate Tectonics?

Continental Drift Hypothesis

Who came up with the Continental Drift Hypothesis?

Alfred Wegener

What did the Continental Drift Hypothesis essentially say?

continents all fit together

What did glaciers have to do with the Continental Drift Hypothesis?

glaciations left on rock showed all continents were together

What is the Distribution of Climate belts in the Continental Drift Hypothesis?

rocks and coal deposits shows everything was together, coal was at equator and now its everywhere

What is the distribution of fossils in the Continental Drift Hypothesis?

many land animals and plants only live in one place, fossils everywhere

What are the matching mountain belts in the Continental Drift Theory?

rock units adjacent to the coastline match

What does SONAR stand for?

Sound Navigation and Ranging

What was SONAR used for (other than warfare)?

bathymetry maps

What is Sea Floor Spreading?

magma comes from sea ridges, forms basalt seafloor, more magma pushes old out of the way, continents connected to sea floor so they must move too

What is subduction?

the sea floor sinks back into the mantle

What is plate tectonics?

explanation for how geosphere works

What is the average thickness and density of a continental plate?

~200km, 2.7g/cc

What are the continental plates made of?

felsic to igneous rocks, silica

How thick and dense are oceanic plates?

~100km, 3.0g/cc

What are the oceanic plates made of?

mafic igneous rocks, high iron

What is a divergent plate boundary?

two plates moving away from each other

Are divergent plates constructive or destructive?

constructive

Where do divergent plate boundaries typically occur?

under the ocean floor, oceanic ridges

What is the main example of underwater convergent boundary?

Mid-Atlantic Ridge

What process involves convergent plate boundaries?

Sea floor subduction

What is a convergent plate boundary?

two plates moving towards each other

What happens during convergence?

denser plate is subducted into mantle

Where do subduction zones usually occur?

deep valleys in the ocean

What plate never gets subducted?

the continental plate

What plate boundaries usually result in volcanoes AND earthquakes?

convergent boundaries

What depth do earthquakes cease at?

660km

At what depth does the descending plate melt in subduction?

~150km

What are the three types of convergent plate boundaries?

ocean-continental, ocean-ocean, continental-continental

What are transform plate boundaries?

two plates sliding past each other

What is a good example of a transform plate boundary?

San Andreas fault

What is the average plate movement speed?

~1-10 centimeters/year

Do active or passive plate boundaries typically have volcanoes and earthquakes?

Active

What are the two driving forces in plate tectonics?

ridge-push, slab-pull

What is ridge-push?

spreading

What is slab-pull?

subduction

What plates collided to form Everest?

Indian and Asian plate

Why does Everest have ocean fossils?

under the Tethys ocean at one point