Earth in Motion: The Plate Tectonics Quiz

If the Earth's outer shell is composed of the crust and the rigid upper mantle, then this layer is called the lithosphere. If the lithosphere is divided into pieces, then those pieces are the tectonic plates.

If two oceanic plates move away from each other, then magma rises from the mantle to fill the gap. If this magma cools and hardens into new crust, then the process is known as seafloor spreading.

If two plates slide past each other horizontally, then friction causes them to lock. If the built-up stress is suddenly released, then an earthquake occurs without the melting required for volcanoes, which defines a transform boundary.

If an oceanic plate is denser than a continental plate, then it will be forced downward during a collision. If it sinks into the mantle, then the process is called subduction.

If the mantle is heated by the core, then the material expands and rises. If it cools near the crust and sinks, then it creates a circular flow or convection current that drags the plates above it.

If two continental plates of similar density collide, then neither can subduct. If the crust is forced upward by the pressure, then massive mountain ranges like the Himalayas are formed.

If tectonic plate movement is driven by slow mantle convection, then the plates move gradually. If the actual rate is similar to the speed of fingernail growth (cm/year), then moving kilometers per year is false.

If all Earth's landmasses were once joined together into a single giant continent, then that landmass is named Pangaea.

If continental crust is pulled apart at a divergent boundary, then the land sinks. If a low-lying valley is created between the separating plates, then it is a rift valley.

If a plate subducts, then it creates a deep-sea trench at the point of entry. If the sinking plate melts and the magma rises, then volcanic arcs form. If the plates grind against each other, then earthquakes occur.

If similar fossils and rock layers are found on separate continents, then they were likely once connected. If the coastlines fit together like puzzle pieces, then it supports the idea that the landmasses drifted apart.

If seafloor spreading creates new crust at a divergent boundary, then the newest rock is at the center of the ridge. If the plates move away, then the older rock is pushed further toward the continents.

If the North American Plate and the Pacific Plate slide horizontally past each other, then the boundary is transform. If the San Andreas Fault is the result of this sliding motion, then it is a transform boundary.

If gravity pulls a dense oceanic plate down into the asthenosphere, then the plate is recycled. If this happens at a convergent boundary, then the process is called subduction.

If oceanic crust is made of basalt and continental crust is made of granite, then their densities differ. If basalt is heavier for its size, then oceanic crust is the denser of the two.

If a plume of magma rises through the middle of a plate, then it is a hot spot. If a chain of volcanic islands forms as the plate moves over this stationary plume, then the Hawaiian Islands are the result.

If tectonic stress is released suddenly, then an earthquake occurs. If magma reaches the surface quickly, then an eruption occurs. If an undersea earthquake displaces water, then a tsunami is generated.

If plates pull apart and magma rises to form new mountains under the sea, then these features are called mid-ocean ridges.

If new crust is hot, then it is less dense. If the crust cools as it moves away from the ridge and more sediment accumulates on top, then its overall density increases.

If Earth's magnetic field reverses over time, then the minerals in new crust record that direction. If the same pattern of stripes exists on both sides of a ridge, then the seafloor must be spreading outward.