* Tensional Stress: As plates pull away from each other, the lithosphere (the Earth's rigid outer layer) experiences tension, which weakens it.
* Faulting: The weakened lithosphere fractures, forming faults, which are breaks in the Earth's crust.
* Subsidence: As the plates continue to move apart, the land between the faults sinks downwards, forming a depression known as a rift valley.
* Volcanic Activity: The process of plate separation often allows magma from the Earth's mantle to rise up, leading to volcanic activity along the rift.
Where rift valleys can form:
* Mid-Ocean Ridges: These are underwater mountain ranges where new oceanic crust is formed. They are prime examples of rift valleys where plates are pulling apart.
* Continental Rifts: These form when continents break apart, creating new oceans. The East African Rift Valley is a well-known example.
* Oceanic-Continental Rifts: These occur when an oceanic plate pulls away from a continental plate. They are less common but can lead to the formation of rift valleys.
Key takeaways:
* Rift valleys form due to divergent plate movement.
* The process involves tension, faulting, subsidence, and often volcanic activity.
* Rift valleys can occur in both oceanic and continental settings.
