Vocabulary
Pieces of Earth's crust
Tectonic plates.
There are ______________ main layers of the Earth.
Four
(crust, mantle, outer core, inner core)
Scientist who created the Continental Drift Theory
Alfred Wegener
Convection currents in the mantle of Earth
Hot air or liquid is less ________________ than cool air or liquid.
dense
A special type of mountain that forms near the subduction zone of a convergent boundary.
The thinnest layer of Earth
Crust
True or False: Evidence shows that Pangaea split into pieces and now the tectonic plates are done moving.
FALSE!
Tectonic plates are still moving at a rate of approximately 2.5 cm per year. If they weren't, there wouldn't be any earthquakes, volcanoes, or mountains!
Where do most earthquakes & volcanoes on Earth occur?
On plate BOUNDARIES.
The San Andreas Fault in California is an example of a ____________________ boundary.
Transform boundary
A/An _________________ is the fast release of energy that results from the build up of stress at a plate boundary.
Earthquake
Two types of crust
1. Continental
2. Oceanic
Three types of plate boundaries
1. Convergent
2. Divergent
3. Transform
The two types of convergent boundaries
1. Subduction (where volcanoes often occur)
2. Collision (where mountains are usually formed)
The Himalayan mountains are the result of a ___________________________ boundary.
Convergent boundary
(Collision)
The theory that all continents are fragments of Pangaea now drifting apart
The Continental Drift Theory
The Earth's crust is thinnest under the _____________________ and thickest under the _____________________.
Thinnest under the ocean.
Thickest under the continents.
Pangaea existed this many millions of years ago
Approximately 250 million years ago
Two tectonic plates aggressively slide against each other in opposite directions. What type of boundary is formed?
Transform
The Mid-Atlantic Ridge running through the Atlantic Ocean is an example of a _____________ boundary.
Divergent
The process that occurs at divergent boundaries under the ocean and produces new oceanic crust.
Seafloor spreading
Heat that drives the movement of tectonic plates comes from this location
Inner core
Continental Drift Theory was not accepted because it did not explain this
HOW the continents moved
(the force)
Two oceanic plates move away from each other. A gap is formed in between them. What fills the gap?
Magma
An oceanic plate and a continental plate move towards each other. What will happen next?
The denser oceanic plate subducts (sinks below) the less dense continental plate.