Volcanic valley formed 10-20 million years
ago by a crack in the Earth's crust and
running about 6,400 km/4,000 mi from the
Jordan valley in Syria through the Red Sea to
Mozambique in SE Africa. At some points its
traces have been lost by erosion, but
elsewhere, as in S Kenya, cliffs rise
thousands of metres. It is marked by a series
of lakes, including Lake Turkana (formerly
Lake Rudolph), and volcanoes, such as Mount
Kilimanjaro.