* Divergent Plate Boundaries: When two continental plates pull away from each other, the lithosphere (the rigid outer layer of Earth) thins and weakens. This allows the hot, less dense material from the mantle to rise towards the surface.
* Upwelling and Stretching: The rising mantle material creates a bulge in the crust, and the stretching forces cause the crust to fracture and break. Over time, these fractures widen and form a valley-like depression, known as a rift valley.
* Examples: The East African Rift Valley is a prime example of a rift valley forming at a divergent plate boundary. It's a massive geological feature stretching for thousands of kilometers across eastern Africa.
Important Note: Rift valleys can also form at divergent boundaries where oceanic plates pull apart, but these are usually filled with water, creating mid-ocean ridges.
