EARTH AND SPACE 1

Which statement best differentiates the seafloor spreading theory from the continental drift theory?

Seafloor spreading explains how new oceanic crust forms, while continental drift describes continental movement without a clear mechanism.

 

Which term describes the supercontinent that existed during the late Paleozoic Period, when most of the Earth’s landmasses were joined together?

Pangaea

During which geologic period did most of the Earth’s landmasses start to separate into distinct continents?

Triassic Period

During which geologic period was the Indian subcontinent rapidly moving northward across the Tethys Ocean toward Asia, which would eventually lead to the formation of the Himalayas?

Cretaceous Period

Which of the following fossils provides the strongest evidence that continents such as Africa, South America, India, and Antarctica were once connected?

Glossopteris

Why is Cynognathus considered strong evidence for continental drift?

 

It was a land-dwelling reptile found in both South America and Africa.

Why is Lystrosaurus considered strong evidence for continental drift?

It was a terrestrial reptile found in Africa, India, and Antarctica.

What role do convection currents in the mantle play in the seafloor spreading process?

They push oceanic plates apart at mid-ocean ridges, allowing new crust to form

The rate of formation of a new seafloor is not always as fast as the destruction of the old seafloor at the subduction zone. What happens when seafloor spreading occurs faster than subduction?

The ocean widens, as with the Atlantic Ocean

Which statement best explains how magma at mid-ocean ridges forms new oceanic crust?

Magma rises from the mantle, cools, and solidifies, forming new oceanic crust.

What pattern of rock ages on the ocean floor provides evidence for seafloor spreading?

Rocks near mid-ocean ridges are youngest, while rocks farther away are older

Where is heat the highest in relation to plate boundaries according to the seafloor spreading theory?

At mid-ocean ridges because magma rises to form new oceanic crust

 

Which observation about earthquakes and volcanoes best supports both continental drift and seafloor spreading theories?

They are concentrated along plate boundaries, showing where crust is created, destroyed, or sliding past other plates.

A student examines a map showing the continental outlines of South America and Africa. Which interpretation applies the concept of continental jigsaw fit?

 

The continents have coastlines that appear to match like puzzle pieces.

A researcher compares fossils of a reptile found in both Africa and South America. What conclusion correctly applies fossil correlation as evidence for plate movement?

The continents were once joined, allowing species to spread across them.

A student tests the seafloor spreading theory by looking at magnetic patterns on the ocean floor. What should they expect to find?

Symmetrical magnetic stripes on both sides of the mid-ocean ridge.

A class examines glacial deposits in present-day India and South Africa. What does this evidence help them apply?

 

These continents were once positioned much closer to the South Pole.

When examining rock layers along the coast of Brazil and West Africa, students notice they have nearly identical compositions. What does this observation suggest about plate movement?

The continents previously shared connected landmasses before separating.

Seafloor drilling reveals that sediments become thicker and older farther from mid-ocean ridges. What conclusion can be drawn?

Spreading centers create young oceanic crust that gradually accumulates sediments as it moves outward from the ridge.

A geologist compares rock samples from a continent and an adjacent ocean basin. The continental rocks are billions of years old, while the oceanic rocks are much younger. Which conclusion best explains this observation?

 

Continents are stable and long-lasting, while ocean basins are constantly renewed and recycled at mid-ocean ridges.