4.1 - Plate Tectonics Flashcards
Name the Earth’s structure in order
- Crust
- Lithosphere
- Asthenosphere
- Mantle
- Core
Name and describe the earth’s structure
- Crust - very outer layer of the lithosphere, earth’s surface
- Lithosphere - thin, brittle layer of rock floating on top of mantle (broken up into tectonic plates)
- Asthenosphere - solid, flexible outer layer of mantle, beneath the lithosphere
- Mantle - liquid layer of magma surrounding core, kept liquified by intense heat from core
- Core - Dense mass of solid nickel, iron, and radioactive elements that release massive amount of heat
3 types of plate boundaries
- Divergent Plate Boundary
- Convergent Plate Boundary
- Transform Fault Plate Boundary
Explain Divergent Plate Boundary
- Plates move away from each other
- Risin magma plum from mantle forces plates apart
- Forms in - mid-Atlantic ridges, volcanoes, seafloor spreading, and rift valleys (on land)
Describe convergent plate boundary
- plates move towards each other
- leads to subduction (one plate being forced beneath another)
Describe transform fault plate boundary
- plates slide past each other in opposite directions
- found in - earthquakes
What cycle is with divergent plate boundaries?
Convection Cycle
Explain the convection cycle
- Magma is heated by the earth’s core and rises through the lithosphere
- Rising magma cools and expands, forcing oceanic plates apart
-Creates mid-ocean ridges, volcanoes, spreading zones (seafloor spreading) - Magma cools and solidifies into new lithosphere
- Spreading magma causes oceanic plates to be pushed under each other (converging/subduction zone)
- The sinking oceanic plate melts back into magma
- Forces magma up, creating narrow, coastal mountains (Andes) and volcanoes on land
What is the Convection Boundary related to
Subduction Zone
Name the 3 subduction zones
- Oceanic-Oceanic
- Oceanic-Continental
- Continental-Contental
Explain Oceanic-Oceanic Subduction Zones
- one plate subducts underneath other
- forces magma up to lithosphere surface, forming mid ocean volcanoes/island arcs
- Where the two meet there is a dent in the ocean, called an off-shore trench
Explain Oceanic-Continental Subduction zones
- dense oceanic plate subducts beneath continental plate and melts into magma
- Forces magma back up to the surface
- Creates costal mountains, volcanoes on land, trenches, and tsunami’s
Explain Continental-Continental Subduction zones
- One plate subducts underneath other, forcing crust upwards
- Creates mountains
Explain in detail transform Fault Boundary
- Plates sliding past each other in opposite directions creates a fault
- Earthquakes - most common activity
- Occurs when rough edges of plates get stuck on each other
- Pressure builds as plates keep sliding, but edges stay stuck
- When stress overcomes the locked fault, plates suddenly release, slide past each other and release energy that shakes the lithosphere
What can a tectonics plate map predict?
- Ring of Fire: pattern of volcanoes all around pacific plate and offshore island arcs
- Transform faults: Likely location of earthquakes
- Hotspots: areas of especially hot magna rising up to the lithosphere (mid ocean islands; hawaii, iceland)
FRQ Practice:
Explain how subduction leads to volcanic activity
As one plate pushes farther down against another plate, it puts pressure on the magma which brings it to the surface. Also, when the plate is pushed far enough down it also turns into magma, creating even more. Where the two plates meet creates volcanoes, and the pressure pushing the magma up through the lithosphere causes them to errupt.
What does a divergent boundary form?
Forms - mid-Atlantic ridges, volcanoes, seafloor spreading, and rift valleys (on land)
What forms in convergent boundaries?
Forms - mountains, island arcs, earthquakes, and volcanoes
