The East African Rift Valley is a prime example of a Graben formed by tensional forces. As the African Plate slowly splits into two (the Nubian and Somalian plates), the crust stretches and fractures. The central block of land subsides between parallel faults, creating a massive, long valley that is often filled with deep lakes. ANSWER: (C) Tensional forces causing crustal fracturing
Share
Rift valleys are significant geographical features representing a nascent divergent plate boundary. In East Africa, tensional forces are pulling the lithosphere apart, causing the crust to thin and fracture. This process, known as rifting, leads to the vertical displacement of rock blocks. The subsided block or Graben, forms the valley floor, while the uplifted sides form steep escarpments or Horsts. This region is a hotbed of tectonic and volcanic activity and is geologically significant as it may eventually lead to the formation of a new ocean basin, similar to how the Red Sea was formed millions of years ago.