How does a rift valley form?
A rift valley forms when continental crust stretches and a long fault-bounded depression develops.
Formation process and geographic mechanism
Extension thins the crust, lowering central blocks along normal faults while edge blocks remain relatively high. Fault scarps, long lakes and linear valleys may develop. Thinning allows hot mantle material to rise, so volcanism and shallow earthquakes can accompany rifting. Not every depression is a rift; evidence of tectonic extension is required.
Spatial outcomes, measurement and management
If extension continues for millions of years, a continent may split, seawater may enter and a new ocean basin can form. Other rifts fail when forces change and remain ancient weaknesses within continents. The East African Rift System displays multiple stages across one broad region. Planning must consider active faults, volcanoes, landslides and changing lake shores together.