H.M.H - Unit 5 Lesson 1 E/E 4 Explaining Plate Motion

What is the main cause of the ground beneath us being in constant motion?

• Tectonic plates moving

• Wind currents

• Ocean tides

• Human activities

Answer explanation

The main cause of the ground beneath us being in constant motion is the movement of tectonic plates. These plates shift due to convection currents in the Earth's mantle, leading to earthquakes and volcanic activity.

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What are convection currents?

• Movements of tectonic plates

• Movements of water in the ocean

• Movements of matter due to density differences

• Movements of air in the atmosphere

Answer explanation

Convection currents are movements of matter caused by density differences, where warmer, less dense material rises and cooler, denser material sinks. This process occurs in fluids, including air and water.

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What role does gravity play in plate motion?

• It pulls the plates towards the sun

• It causes the plates to float

• It causes the weight of the rock at the ridge to push the plate

• It stops the plates from moving

Answer explanation

Gravity influences plate motion by causing the weight of the rock at mid-ocean ridges to push the tectonic plates apart. This process, known as ridge push, is a key driver of plate tectonics.

What happens at mid-ocean ridges?

• Plates stop moving

• Old rock sinks into the Earth

• New, warm rock sits higher than older rock

• Volcanic eruptions occur

Answer explanation

At mid-ocean ridges, new, warm rock rises from the mantle, creating new oceanic crust. This rock is less dense and sits higher than older, cooler rock, which is why the correct answer is that new, warm rock sits higher than older rock.

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What can the movement of tectonic plates cause?

• Sudden events like volcanic eruptions and earthquakes

• Formation of new oceans

• Changes in weather patterns

• Increase in Earth's temperature

Answer explanation

The movement of tectonic plates can lead to sudden events like volcanic eruptions and earthquakes, as these processes occur at plate boundaries where stress builds up and is released.

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The diagram represents a convection current in Earth's mantle.

Descriptions of the events at each of the positions are shown.

Match the descriptions of the events to the numbers in the diagram.

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a

b

c

d

2

3

1

4

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What causes convection currents?

• Hot magma rises while cool magma sinks

• The rotation of the Earth

• Ocean currents pulling plates apart

• The spinning of the Earth's core

Answer explanation

Convection currents are caused by the movement of hot magma rising and cool magma sinking. This process creates a cycle that drives the movement of tectonic plates, making the first answer choice correct.

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What is D indicating?

• magma

• upper mantle

• lava

• convection

Answer explanation

D indicates convection, which is the process of heat transfer in fluids, including the movement of magma in the Earth's mantle. This process drives plate tectonics and volcanic activity.

What causes convection currents?

• Hot magma rises while cool magma sinks

• The rotation of the Earth

• Ocean currents pulling plates apart

• The spinning of the Earth's core

Answer explanation

Convection currents are caused by the movement of hot magma rising and cool magma sinking. This process creates a cycle that drives the movement of tectonic plates.

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The process by which tectonic plates move due to the convection currents in the mantle

• Subduction

• Plate Tectonics

• Seafloor Spreading

• Conduction

Answer explanation

Plate tectonics is the scientific theory that explains the movement of tectonic plates caused by convection currents in the Earth's mantle, leading to various geological phenomena.

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