The East African Rift Valley illustrates the formation of divergent plate boundary in a continental ...

(a) Rising magma beneath a continent pushes the crust up, producing numerous fractures,
faults, rift valleys, and volcanic activity.
(b) As the crust is stretched and thinned, rift valleys develop, and lava flows onto the valley
floorssuch as seen today in the East African Rift Valley.
(c) Continued spreading further separates the continent until it splits apart and a narrow
seaway develops. The Red Sea, which separates the Arabian Peninsula from Africa, is a good
example of this stage of development.
(d) As spreading continues, an oceanic ridge system forms, and an ocean basin develops and
grows. The Mid-Atlantic Ridge illustrates this stage in a divergent plate boundarys history.