What causes the movement of Lithospheric plates?

Correct Option

The correct option is

Movement of molten magma inside the earth

Explanation

The theory of Plate Tectonics states that the Earth's lithosphere is divided into massive, irregular slabs called tectonic plates. These plates float and move horizontally over the semi-molten asthenosphere. The mechanism driving this movement is fundamentally different from the forces proposed in earlier theories like Continental Drift.

Option Analysis

• Gravitational pull of the moon is Incorrect: The gravitational pull of the moon (tidal force) was proposed by Alfred Wegener as a driving force for Continental Drift. However, scientific evidence has proven that these forces are far too weak to move the massive lithospheric plates.
• Movement of molten magma inside the earth is Correct: The movement of lithospheric plates is driven by convection currents within the Earth's mantle. Heat generated from radioactive decay and residual primordial heat causes molten magma to rise, spread laterally beneath the lithosphere, and sink as it cools. This circulating movement creates friction and drag, propelling the overlying plates.
• Rotation of the earth is Incorrect: The rotation of the Earth generates a centrifugal force known as the "pole-fleeing force." While Wegener suggested this contributed to the equator-ward movement of continents, it is not strong enough to drive plate tectonics.
• Weight of the oceans is Incorrect: The weight of the oceans contributes to isostatic adjustment (vertical balance) but does not generate the lateral forces required to move tectonic plates horizontally.

Key Takeaway: The primary force driving the movement of lithospheric plates is the convectional current system operating in the mantle, fueled by the Earth's internal heat.