Due to the pressure of the magma. Cause a rift The magma heat transfer into the crust had a temperature and pressure drop. It became the Rift Valley tectonic subsidence in duration than later, when the water is accumulated sea. And caused a rift caused deep magma pushes it moving again. Southern Ocean caused the earth to separate the two sides occurred. The expansion of the sea floor (Sea floor spreading) and mountain causing mid-oceanic areas such as the Red Sea. Gulf of California East Africa The Rift Valley has separate tracks. Shallow earthquakes Volcanoes and lava flows beneath the ocean.