Question

1. according to the theory of plate tectonics, what causes the earths tectonic plates to move?

a) they float upon the fluid mantle and move due to gravity, convection currents, and pressure.
b) they shift due to eruptions of molten rock that occur within the earths core.
c) they shift and settle when gravitational changes occur due to the earths revolution around the sun.
d) they are pulled in different directions due to the earths changing magnetic field.

Explanation:

To solve this, we analyze each option:

• Option A: Tectonic plates float on the semi - fluid mantle. Convection currents in the mantle, along with gravity and pressure, drive plate movement. This aligns with plate tectonics theory.
• Option B: Molten rock eruptions (volcanism) are a result of plate movement, not the cause of it. The core doesn't have molten rock eruptions that move plates.
• Option C: The Earth's revolution around the Sun doesn't cause gravitational changes that move tectonic plates. Plate movement is internal to the Earth.
• Option D: The Earth's magnetic field doesn't pull tectonic plates. Magnetic field changes are related to core processes but not plate movement.

Answer:

A. They float upon the fluid mantle and move due to gravity, convection currents, and pressure.