Forces and Dynamics of Plate Tectonics

How do current dynamic models explain plate movement compared to earlier textbook models?

• Earlier models focused on gravity-driven convection, while current models emphasize mantle convection cells.

• Current models suggest mantle convection cells directly push plates, while earlier models focused on gravity.

• Earlier models proposed mantle convection cells pushing plates from below, while current models describe a gravity-driven convection system.

• Both models agree on the primary role of mantle convection cells, differing only in scale.

What are lithospheric plates composed of?

• Only oceanic or continental crust.

• The entire mantle.

• A layer of crust on top of the lithospheric mantle.

• The asthenosphere and the crust.

Which statement accurately describes the asthenosphere?

• It is a rigid, solid layer that prevents plate movement.

• It is a hotter, less rigid mantle rock that can slowly flow.

• It is a liquid layer that directly drives plate tectonics.

• It is the outermost, brittle part of the Earth's mantle.

How does the depth of the ocean floor relate to the age of the underlying plate?

• Ocean depth decreases with the age of the underlying plate.

• Ocean depth increases with the age of the underlying plate.

• Ocean depth is unrelated to the age of the underlying plate.

• Ocean depth is constant regardless of plate age.

What happens to the lithospheric plate as it moves away from a mid-ocean ridge?

• It becomes thinner and hotter.

• It becomes thicker and hotter.

• It becomes thinner and cooler.

• It becomes thicker and cooler.

At what temperature does the lithosphere become brittle enough to fracture and produce earthquakes?

• Above 1300°C.

• Below 600°C.

• Between 600°C and 1300°C.

• Only at the very top surface (4°C).

How does the force of ridge push change with distance from a spreading ridge?

• It is strongest at the ridge and decreases with distance.

• It is zero at the ridge and increases with distance and age.

• It is constant across the entire plate.

• It is only present in subduction zones.

What causes the slab pull force in subduction zones?

• Hot, buoyant oceanic lithosphere rising from the asthenosphere.

• The friction between the oceanic and continental plates.

• The enhanced gravitational force on cooler, denser rocks in the subducting plate.

• Mantle convection cells pushing the plate from below.

Which force is generally considered larger in driving plate tectonics?

• Mantle convection.

• Ridge push.

• Slab pull.

• Volcanic activity.

What is the ultimate energy source for plate tectonics?

• Solar radiation.

• Earth's internal heat.

• Tidal forces from the Moon.

• Chemical reactions in the crust.