The East African Rift Valley formed as a result of what type of plate boundary?

• A. Divergent boundary
• B. Convergent boundary
• C. Transform boundary
• D. Hotspot volcanism

Answer: (A)

Rift valleys form where the crust is stretched and pulled apart, causing extension of the lithosphere. At a divergent boundary, tectonic plates move away from each other, the crust thins, and normal faults develop as blocks drop and sink, creating a down-dropped valley. The East African Rift Valley is a classic example of continental rifting: forces within the African Plate are pulling the land apart, the crust thins and magma from the mantle can rise to fill the gaps, sometimes producing volcanic activity along the rift. If this divergence continues, the rift can widen into a new ocean basin as separate landmasses drift apart. This differs from convergent boundaries, which compress and build mountains; transform boundaries, which slide past one another; and hotspot volcanism, which arises from localized mantle plumes rather than a plate boundary.