The
Great Rift Valley is a geologic depression (rift)
that extends from Syria in south western Asia to
Mozambique in south eastern Africa. It takes the
form of a series of valleys and bodies of water that
are bounded by parallel fault lines. The Great Rift
Valley is widening slowly but surely, in the process
causing many volcanic eruptions and earthquakes in
the area. The great Rift valley is also visible from
outer space as a rift of two parallel lines.
Some 20 million years
ago, the earth's crust weakened and tore itself
apart creating a jagged rift, thousands of
kilometres long, across the Eastern end of the
African continent. The land on either side erupted
creating great volcanic mountains, while the valley
floor gradually sank into a low flat plain. This
geologic phenomena, dubbed the Great Rift Valley by
the Scottish explorer John Walter Gregory, divides
Kenya neatly down the length of the country
essentially separating east from west.
Today, The Rift Valley
is characterized by uninhabitable desert and fertile
farmland, flat arid plains and steep escarpments.
The great Rift Valley is also the home to millions
of wildlife and hosts the worlds most renowned game
parks and reserves (the Maasai Mara in kenya and The
Serengeti in Tanzania). In some places this natural
divide is up to 100 km (60 miles) wide, while it
reaches its narrowest point just north of Nairobi at
45 km wide.
The valley floor is at its
lowest near Lake Turkana where there is virtually no
distinction between the Great Rift and the surrounding
desert. As it heads south, however, the valley walls form
sheer cliffs rising to 1,900 km (6,232 ft) at Lake Naivasha.
After Naivasha, the valley descends again to 580 meters
(1,902 feet) at the Tanzanian border.
Subterranean movement
is common today as the Rift Valley is home to thirty
active and semi-active volcanoes and countless hot
springs along its length. This string of alkaline
lakes and boiling springs northwest of Nairobi
includes Lake Baringo, Lake Bogoria, Lake Nakuru,
Lake Elementaita, Lake Naivasha, and Lake Magadi in
the south. In the noth is lake Turkana.
These lakes are unique because their
water is highly concentrated in sodium carbonate.
This situation is caused by the high alkalinity from
the surrounding volcanic rocks coupled with poor
drainage outlets due to the steep sides of the
valley. The high evaporation of the surface lake
water results in sodium carbonate which, in turn,
creates an ideal breeding ground for algae. Several
species of fish, tilapia in particular, thrive in
this environment. As a result, millions of birds
flock to these soda lakes to feast on the abundant
food supply of algae and fish. Each of the lakes in
the East African Rift Valley string have a slightly different
water composition ranging from freshwater to
extremely alkaline, highly saline to brackish.
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