Layers
What is the Earth's outermost layer ?
The crust.
What is the boundary where the plates move away from each other ?
Divergent boundary.
What is the definition of plates ?
Pieces on Earth that are separated by cracks.
Who is Alfred Wegener ?
A meteorologist and geophysicist who formulated the first complete statement of the continental drift hypothesis.
What did scientists use to map mid-ocean ridges with ?
Sonar.
What is the Earth's second-outermost layer ?
The mantle.
What is the boundary where plates slide past each other ?
Transform boundaries.
A theory explaining the structure of Earth's crust.
What exactly was wegener's theory ?
That all continents were once joined together in a single landmass and had since drifted apart.
What is one piece of evidence scientists used for sea-floor spreading ?
Ocean material, magnetic stripes, or drilling samples.
What is the Earth's inner most layer ?
The inner core.
What is the boundary where the plates collide ?
Convergent boundaries.
What forms when pieces of Earth's crust diverge on land ?
Rift valley.
When was Wegener's theory considered ?
In the 1950s.
What happens at deep-ocean trenches ?
The oceanic crust bends downward.
What is the Earth's layer that's above the inner core ?
The outer core.
Which boundary forms mountains ?
Convergent boundaries.
What is Pangea?
A supercontinent that is believed to have had all of the Earth's current landmasses.
Continental drift.
How many different boundaries are there ?
Three.
What is the mostly-solid bulk of Earth's interior ?
The mantle.
Which boundary can form volcanic islands ?
Divergent boundaries.
What is subduction ?
The process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle again.
What is the title of the book that Wegener published his evidence for continental drift in ?
The Origin of Continents and Oceans.
What does the theory of plate tectonics state ?
Earth's plates are in slow, constant motion, driven by convection currents in the mantle.