How does a Rift Valley Form

Guys help, formation of a rift valley

Rift valleys are downthrows or grabens which slide down between two fault lines.

They're are believed to be formed as a result of tensional forces (when plates are pulled apart).
These tensional forces can be created by magma blisters within the crust which exert tensional pressure causing the crust to snap.
The East African Rift Valley is believed to have formed this way