Quiz: Plate Tectonics - Evidence of Past Plate Motions

Question 1

Fossils of Mesosaurus, a small freshwater reptile, are found only in southern Africa and eastern South America. What is the best explanation?

Accepted Answer

The continents were once joined when Mesosaurus lived

Question 2

The close fit between the coastlines of South America and Africa, by itself, proves the continents were once joined.

Accepted Answer

false

Question 3

Alfred Wegener named the ancient supercontinent that contained all of Earth's landmasses _____.

Accepted Answer

Pangaea

Question 4

Matching rock layers of the same age and type appear in the Appalachian Mountains (North America) and Scotland. What do these data suggest?

Accepted Answer

The mountain ranges formed as one range before the continents separated

Question 5

Glacial scratches and deposits from 300 million years ago are found in India, Africa, and Australia, which are warm today. Explain how these data support continental drift.

Accepted Answer

These continents must once have been located near the South Pole and joined, so one ice sheet covered them. Over time the plates moved toward warmer latitudes, carrying the glacial evidence with them.

Question 6

Rock samples collected moving away from a mid-ocean ridge get older on both sides. What does this pattern show?

Accepted Answer

New seafloor forms at the ridge and spreads outward

Question 7

Sediment on the ocean floor is usually thinnest near mid-ocean ridges and thicker farther away.

Accepted Answer

true

Question 8

The process in which new oceanic crust forms at a mid-ocean ridge and moves away from it is called _____.

Accepted Answer

seafloor spreading

Question 9

Rocks on both sides of a mid-ocean ridge show symmetrical stripes of normal and reversed magnetic polarity. What best explains the symmetry?

Accepted Answer

Crust forms at the ridge and records Earth's field as it spreads both ways

Question 10

Deep-ocean trenches have the oldest seafloor nearby, yet the ocean floor is never older than about 200 million years. Explain what happens to old seafloor and why.

Accepted Answer

Old, dense oceanic crust sinks back into the mantle at trenches through subduction. Because seafloor is constantly recycled, it never gets very old compared to continental rock.

Question 11

Fossils of the seed fern Glossopteris across southern continents are strong evidence because its heavy seeds could not travel across oceans.

Accepted Answer

true

Question 12

Coal, which forms from tropical swamp plants, is found in Antarctica. Which conclusion best fits this evidence?

Accepted Answer

Antarctica was once located closer to the equator

Question 13

Long underwater mountain chains where tectonic plates pull apart are called _____.

Accepted Answer

mid-ocean ridges

Question 14

Why did many scientists reject Wegener's continental drift hypothesis in the early 1900s?

Accepted Answer

He could not explain what force moved the continents

Question 15

Earthquakes and volcanoes occur randomly across Earth's surface with no connection to plate boundaries.

Accepted Answer

false

Question 16

A map shows a deep trench beside a chain of volcanoes on the west coast of South America. Analyze what type of plate interaction this suggests and why.

Accepted Answer

This suggests a convergent boundary where the oceanic plate subducts under the South American plate. The trench forms where the plate bends down, and melting rock rises to form volcanoes.

Question 17

The Atlantic Ocean widens about 2.5 cm per year. Which data source best measures this present-day motion?

Accepted Answer

GPS stations on different continents

Question 18

When one tectonic plate sinks beneath another into the mantle, the process is called _____.

Accepted Answer

subduction

Question 19

Heat-driven convection currents in the mantle are thought to help move tectonic plates.

Accepted Answer

true

Question 20

The Himalayas contain marine fossils near their peaks. What best explains this?

Accepted Answer

Two continental plates collided and pushed seafloor rocks upward

Question 21

Compare the ages of oceanic crust and continental crust. Use this comparison to explain why continents preserve evidence like ancient fossils better than seafloor.

Accepted Answer

Continental crust can be billions of years old, while oceanic crust is under about 200 million years. Continental crust is less dense and is not subducted, so it keeps old fossils and rocks.

Question 22

East Africa has a long valley with active volcanoes and frequent earthquakes. What is most likely happening there?

Accepted Answer

The continent is beginning to split apart

Question 23

The rigid outer layer of Earth, made of crust and upper mantle and broken into plates, is the _____.

Accepted Answer

lithosphere

Question 24

Transform boundaries, like the San Andreas Fault, mostly create new crust as plates slide past each other.

Accepted Answer

false

Question 25

A student claims, 'Matching fossils on two continents prove the animals swam across the ocean.' Use at least two types of evidence to argue whether this claim is supported.

Accepted Answer

The claim is not supported. Matching rock layers and mountain ranges, plus seafloor spreading data showing the ocean widened over time, indicate the continents were joined, not that animals swam.

Quiz: Plate Tectonics - Evidence of Past Plate Motions

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