Earth’s Layers & Structure
This rigid layer includes the crust and upper mantle.
What is the Lithosphere?
These geological “pieces” carry both the continents and oceans.
What are the tectonic plates?
He proposed the theory of Continental Drift in 1912.
Who is Alfred Wegener?
These underwater mountain chains form where plates pull apart under the ocean.
What are mid-ocean ridges?
These daily ocean movements are caused by the gravitational pull of the Moon and Sun.
What are tides?
This layer is soft, plastic, and allows plates to move above it.
What is the asthenosphere?
These currents in the mantle act as the “engine” of plate movement.
What are convection currents?
Wegener used this “puzzle-piece” observation of two specific continents as evidence.
What is the fit of South America and Africa?
This mountain range formed from continental–continental convergence.
What are the Himalayas?
Earth’s seasons are caused by this, not by how close Earth is to the Sun.
What is Earth’s 23.5° axial tilt?
This Earth layer is responsible for generating the magnetic field.
What is the liquid outer core?
This type of plate boundary forms rift valleys when happening on land.
What is a divergent continental–continental boundary?
This evidence shows matching direction of ancient glaciers on continents now far apart.
What are ancient climate clues?
This deep underwater feature forms where one tectonic plate bends and sinks beneath another at a convergent boundary.
What is an ocean trench?
This phase of the Moon occurs when the Moon is between the Earth and the Sun, and its lit side faces away from us.
What is a new moon?
This type of material in a convection cell rises.
What is hot and less dense?
This process occurs when a denser plate sinks below another plate.
What is subduction?
This pattern in ocean rock proves that Earth’s magnetic field has reversed many times.
What is paleomagnetism?
This volcanic arc in South America formed from oceanic–continental convergence.
What are the Andes Mountains?
The leading hypothesis for the Moon’s formation states it formed from debris after this Mars-sized object struck Earth.
What is Theia?
This extremely hot layer is solid because of immense pressure, not because of its temperature.
What is the inner core?
At this type of boundary, plates slide past each other, causing major earthquakes.
What is a transform boundary? (e.g., San Andreas Fault)
Wegener lacked this key mechanism, which was later provided by mid-ocean ridge research.
What is seafloor spreading?
This type of convergence forms volcanic island arcs, like Japan.
What is oceanic–oceanic convergence?
This metric system prefix means “one billion,” as in the distance of a light-year measured in meters.
What is “giga-”?