Which is an example of a continental rift valley?

• A. East African Rift Valley
• B. Mariana Trench
• C. Great Barrier Reef
• D. Andes Mountain Range

Answer: (A)

Continental rift valleys form when continental crust is stretched and pulled apart, causing normal faults to drop blocks of crust and create a long, down-dropped trough. The East African Rift Valley is the classic example: the African plate is undergoing extension, producing parallel faults and down-dropped blocks that form a trough often filled by lakes and volcanic activity along the rift. This explains why it’s a continental rift valley. The Mariana Trench is an oceanic trench formed by subduction, not rifting of continental crust. The Great Barrier Reef is a coral reef system on a continental shelf, not a rift valley. The Andes result from subduction and continental collision, not from the extensional processes that create rift valleys.