Geology Reference
In-Depth Information
In this region, the Red Sea and the Gulf of Aden are actively spreading, while Africa's rift
valley has stopped spreading. Africa's rift valley is called the
failed rift,
while the Red Sea
and Gulf of Aden are
active rifts.
Rifting of continental crust begins when heated mantle rocks and magma rise up under-
neath the continent, forcing the crust upward until the stress causes it to crack. As the
continental crust moves apart, eventually a rift is wide enough that nearby ocean water
spills in, creating a small sea. For example, the rift along the floor of the Red Sea began
as a rift between the continental rocks of Egypt and the Arabian Peninsula. Already the
ridge along the floor of the Red Sea is creating new basalt rock. As rifting continues, this
small sea becomes the first stage of a new ocean basin.
This means that what starts as a continental divergence eventually becomes
an oceanic plate divergence, when the continental plates are far enough apart that
ocean lies between them. Scientists think this series of events is how all ocean
basins begin.
