Q. A Rift Valley is:
Answer: a valley with steep fault-scarps and block mountains on both sides
Notes: A rift valley is a valley with steep fault scarps and block mountains on both sides. Rift valleys are formed when tension causes the central portion to be let down between two adjacent fault blocks. The East African Rift Valley system is an example of a rift valley. Block mountains are formed when large areas of the earth break and subside vertically. The uplifted blocks are called horsts and the lowered blocks are called graben. The Sierra Nevada mountain range in California is an example of fault block mountains. Block mountains are formed when two tectonic plates move away from each other, causing cracks on the surface of the Earth. This forces a slab of land to break off and is forced upwards.