Unit D - Plate Tectonics Flashcards
What are the different layers that make up the earth?
Crust - solid - thinnest
Mantle - thickest
- Upper Mantle - solid - 60km
- Lower Mantle - liquid - 2000km
Outer Core - liquid
Inner Core - solid (extreme pressure)What is the lithosphere?
The first 100km below the earth’s surface. (Crust and Upper Mantle)
“Litho” means stone.
About how old is the earth?
Earth is about 4.5 billion years old.
What is continental drift?
The idea that the continents were once joined together to form a large land mass called Pangaea, and slowly drifted apart over geological time.
What was Alfred Wegener’s evidence that the continents have moved?
Edges of continents fit like a puzzle
Matching plant and reptile fossils found on separate continents
Mountains with matching rock layers found on separate continents
Tropical plant fossils in Antarctica
What is the theory of plate tectonics?
The surface of the earth is made up of large plates that have moved over geological time.
The plates have moved toward and away from each other to form continents, mountains, and oceans.
What causes an earthquake?
As the huge lithospheric plates move, large sections of rock break and shift position releasing energy waves.
How does information about earthquakes and volcanoes help to map tectonic plates?
Earthquakes and volcanoes mainly occur along plate boundaries because of plates moving in different directions.
Scientists mapped the boundaries by plotting the eruptions and quakes.
What are the different types of plate boundaries?
Convergent 2 Continental: Plates collide –> (Mid-Atlantic Ridge)
Transform: plates sliding past each other causing earthquakes /\ \/ (US West Coast)
Where do mountains form?
Regular Mountains:
Get pushed up at convergent 2 continental boundaries where the plates collide head-on
Volcanic Mountains:
At convergent subduction zones where one oceanic plate slides under another.
At divergent boundaries when plates spread apart.
Form at Hot Spots: a place where magma melts through the earth’s lithosphere.
What is the current theory on why plates move?
Convection Currents in the mantle below the lithosphere push and pull the plates around.
Convection Current:
Magma heats at the bottom of the mantle (hot core)
Rises
Cools near the top of the layer (under litho)
Falls back down
Core heats it again…
What are the three main types of rocks?
Igneous, Sedimentary, Metamorphic
How is each category of rock determined?
Method of formation:
Igneous - cooling magma/lava
Sedimentary - weathered rock cemented/compacted together
Metamorphic - heat and pressure change a rock into another rock
What is the rock cycle?
It is a diagram which shows how rocks are formed and changed from one rock type to another.
