asthenosphere

atmosphere

lithosphere

troposphere

Present-day continents of South America and Africa are moving toward each other.

Continents move due to changes in the Earth's orbit around the Sun.

Present-day continents of South America and Africa once fit together like a jigsaw puzzle.

Continents move due to changes in the tilt of the Earth's axis.

crustal plate boundaries

interior areas of continental crustal plates

polar regions of the Earth

interior areas of oceanic crustal plates

Lithospheric plates are destroyed at the mid-ocean ridges.

Continents drift because they rest on lithospheric plates that move.

Lithospheric plates move because the inner core of the Earth is liquid.

Transform boundaries form when two lithospheric plates collide.

global warming

law of conservation of mass

seismic probability

theory of plate tectonics

Gondwanaland

Pangaea

Eurasia

Atlantis

the interior of an oceanic crust plate

boundary between the core and mantle

near a fault zone

near the equator

The theory of plate tectonics was a less complete theory because it failed to provide complete reasons and mechanisms for why the plates and continents moved.

The theory of plate tectonics was a more complete theory because it provided a reason and mechanism for why the plates and continents moved.

The theory of plate tectonics was a more complete theory because it failed to provide reasons and mechanisms for why the plates and continents moved.

The theory of plate tectonics was a less complete theory because it provided a reason and mechanism for why the plates and continents moved.

Older rocks are found near the deep-ocean trenches.

Older rocks are near the center of mid-ocean ridges.

Younger rocks are near the deep-ocean trenches.

Younger rocks are mixed with older rocks at mid-ocean ridges.

Earth's crust is thinnest under oceans.

Earth's crust is uniform in thickness.

Earth's crust is thinner under the poles and thicker at the equator.

Earth's crust is thinnest under mountainous regions.

They occur when a less dense plate is pushed below a more dense oceanic plate.

They result in mountains formed when two continental plates collide.

They always result in sea-floor spreading.

They always occur at convergent plate boundaries.

convergent

divergent

subduction

transform

They have been drifting farther apart.

They have been drifting closer together.

They have remained the same distance apart.

They drifted further apart and then drifted closer together.

A volcanic island arc and an ocean trench will form.

A non-volcanic mountain range will form.

An on-shore volcanic arc and an ocean trench will form.

A rift valley will form.

Plate A would subduct beneath Plate B, forming an oceanic volcano.

Plate B would subduct beneath Plate A, forming a deep trench.

Plates A and B would collide, forming an oceanic ridge and a volcanic arc.

Plates A and B would thrust rocks upward, forming a fold mountain.

oceanic-oceanic divergent plate boundary

continental-continental divergent plate boundary

continental-continental convergent plate boundary

oceanic-continental convergent plate boundary

An oceanic plate collides with a continental plate pushing at a convergent boundary pushing both plates upward in to jagged rock formations.

Two continental plates of equal density collide into each other at a convergent boundary crumpling and crushing under the pressure and folding upward creating jaded rock formations.

Two continental plates of equal density collide into each other at a divergent boundary crumpling and crushing under the pressure and folding upward creating jaded rock formations

Two continental plates of equal density collide into each other at a convergent boundary crumpling and crushing under the pressure and folding upward creating jaded rock formations over the course of millions of years.

Two oceanic plates of equal density collide into each other at a divergent boundary pushing away from each other as the seafloor spreads.

One oceanic plate and one continental plate at a divergent boundary are pushed away from each other by rising magma that fills in the rift valley creating mid-oceanic ridges, thereby creating new seafloor

Two oceanic plates at a divergent boundary are pushed away from each other by rising magma that fills in the rift valley creating mid-oceanic ridges and new seafloor over the course of millions of years.

Two oceanic plates at a divergent boundary are pushed away from each other by rising magma that fills in the rift valley creating mid-oceanic ridges, thereby creating new seafloor.

Two continental plates of equal density grind past each other at a convergent boundary, neither creating nor destroying any landforms rather creating folds and ripples in the land that look like a series of smaller hills next to the fault line

Two continental plates of equal density collide into each other at a convergent boundary crumpling and crushing under the pressure and folding creating jaded rock formations over millions of years.

Two continental plates of grind past each other at a transform plate boundary creating mountains and a rift valley along the fault line.

Two continental plates of equal dencity grind past each other at a transform plate boundary, neither creating nor destroying any landforms, rather creating folds and ripples in the land that look like a series of smaller hills next to the fault line.