Here's why:
* Convergent Boundaries: These are where tectonic plates collide. The pressure causes mountains, volcanoes, and deep ocean trenches to form.
* Divergent Boundaries: These are where tectonic plates move apart. The space created allows magma from the Earth's mantle to rise and erupt, creating new crust.
How Rift Valleys Form:
1. Plate Separation: The plates move apart, creating a gap.
2. Magma Upwelling: The gap allows magma from the mantle to rise.
3. Volcanic Activity: Magma erupts, creating volcanoes and new crust.
4. Faulting and Subsidence: The pressure from the rising magma causes the crust to fracture and sink, creating a valley.
Examples of Rift Valleys:
* East African Rift Valley: A prominent example, stretching over 3,000 kilometers.
* Mid-Atlantic Ridge: A submerged rift valley that forms the boundary between the North American and Eurasian Plates.
So, while convergent boundaries create mountains and trenches, divergent boundaries are responsible for the formation of rift valleys.
