Earth's Structures Unit Review

Front

What is the most likely cause of the geological features in a mid-ocean ridge?

Back

Rising convection currents in the mantle.

Answer explanation

The geological features of mid-ocean ridges are primarily caused by rising convection currents in the mantle, which create new oceanic crust as tectonic plates diverge. This process leads to the formation of ridges.

Front

Why does the oceanic crust sink beneath the continental crust at a subduction boundary?

Back

The oceanic crust is denser.

Answer explanation

The oceanic crust is denser than the continental crust, which causes it to sink beneath the continental crust at a subduction boundary. This density difference is the primary reason for the subduction process.

Front

What is the most likely cause of the earthquakes near a plate boundary?

Back

Subduction of a crustal (tectonic) plate

Answer explanation

The most likely cause of earthquakes near a plate boundary is the subduction of a crustal plate, where one tectonic plate moves under another, creating stress and leading to seismic activity.

Front

How is heat transferred from the Earth’s interior to its crust?

Back

Convection in the mantle.

Answer explanation

Heat is transferred from the Earth's interior to its crust primarily through convection in the mantle, where hot material rises and cooler material sinks, facilitating the transfer of heat.

Front

Why do earthquakes and volcanic activity occur along the Pacific Ring of Fire?

Back

It is located at the boundaries of tectonic plates.

Answer explanation

Earthquakes and volcanic activity occur along the Pacific Ring of Fire because it is located at the boundaries of tectonic plates, where the movement and interaction of these plates create geological activity.

Front

Where are the convection currents that cause tectonic plate motion located?

Back

Mantle

Answer explanation

Convection currents that drive tectonic plate motion are located in the mantle. These currents result from the heat from the Earth's core causing the mantle material to move, which in turn moves the tectonic plates above.

Front

Where do earthquakes most likely occur?

Back

Where tectonic plates are sliding past each other.

Answer explanation

Earthquakes most likely occur where tectonic plates are sliding past each other, known as transform boundaries. This movement causes stress to build up, leading to seismic activity.

Front

What is least likely to occur at a tectonic plate boundary where the plates are moving towards each other?

Back

Sea-floor spreading

Answer explanation

Sea-floor spreading occurs at divergent boundaries where plates move apart, not at convergent boundaries where plates move towards each other. Therefore, it is least likely to occur in such areas.

Front

Which of the following provides evidence for continental drift?

• Movement of the Australian continent was observed
• Africa and South America have the same type of climate
• Fossils of the same plants and animals have been found in Africa and South America
• Plants and animals found in Africa differ from those found in Australia

Back

Fossils of the same plants and animals have been found in Africa and South America

Answer explanation

The presence of identical fossils of plants and animals in Africa and South America supports the theory of continental drift, indicating these continents were once connected.

Front

What feature of the ocean floor develops from divergent plates?

Back

Mid-ocean ridge

Answer explanation

Divergent plates move apart, allowing magma to rise and create new oceanic crust. This process forms mid-ocean ridges, which are underwater mountain ranges, making it the correct feature associated with divergent plate boundaries.