Constructive margins

What happens when two plates pull apart?

• A stronger zone in the crust forms

• A weaker zone in the crust forms

• The crust remains unchanged

• The crust becomes thicker

What is the main feature of a rift valley?

• High mountains

• Deep valleys

• Wide plateaus

• Narrow ridges

What causes the upwelling of magma under the earth's continental lithosphere?

• Ocean currents

• Convection currents in the asthenosphere

• Wind patterns

• Tectonic plate collisions

What is the role of convection currents in the formation of rift valleys?

• They cause the crust to thicken

• They lead to volcanic eruptions

• They stretch the crust thinner

• They create ocean currents

What is the expected outcome of the Great African Rift Valley's geological activity?

• Formation of a mountain range

• Creation of a new ocean

• Development of a desert

• Emergence of a new island

What type of boundary is associated with the Great African Rift Valley?

• Convergent

• Divergent

• Transform

• Static

What is the primary cause of the formation of mid-ocean ridges?

• Erosion

• Sedimentation

• Seafloor spreading

• Glacial movement

What causes the upwelling of magma under the earth's oceanic lithosphere?

• Convection currents in the asthenosphere

• Tectonic plate collisions

• Ocean currents

• Wind erosion

What feature may be found at the central part of a ridge?

• A mountain peak

• A central (rift) valley

• A desert basin

• A coral reef

What can cause the lithosphere to split and create a 'plate boundary'?

• Cooling of magma

• Rising magma and subsequent cooling

• Wind erosion

• Ocean currents