The Earth's crust is moved by plate tectonics, a theory that explains the movement of the Earth's lithosphere (the rigid outer layer). Here's a breakdown of the key factors:

1. Convection Currents in the Mantle:

* The Earth's mantle, a layer of hot, semi-solid rock, undergoes convection.

* Hotter, less dense material rises, while cooler, denser material sinks.

* This creates a circular flow of material within the mantle.

2. Drag on the Plates:

* The convection currents in the mantle drag the tectonic plates along with them.

* The plates are like rafts floating on the moving mantle.

3. Ridge Push and Slab Pull:

* Ridge Push: At mid-ocean ridges, where new crust is formed, the rising magma pushes the plates apart.

* Slab Pull: At subduction zones, where one plate slides beneath another, the dense, sinking plate pulls the rest of the plate along with it.

4. Plate Boundaries:

* The interactions between these moving plates at their boundaries are responsible for many of the Earth's geological features, such as:

* Volcanoes: Occur where plates converge or diverge.

* Earthquakes: Caused by the release of built-up stress at plate boundaries.

* Mountain Ranges: Formed when plates collide.

In summary, the Earth's crust is moved by a combination of forces driven by the convection currents within the mantle, along with the forces of ridge push and slab pull.