Page 66 - Super Earth Encyclopedia

“Every year,
FRACTURED CONTINENT Africa gets a

little closer to
GREAT RIFT VALLEY splitting into

two continents.”
Magma rising through the
Rift Valley floor has fueled the
Most of the spreading rifts in Earth’s crust lie on the eruption of the Virunga volcanoes.
ocean floor. But one passes right through Africa, and is
tearing it apart—East Africa is pulling away from the rest
of the continent, opening up a vast rift valley that extends
from Mozambique to the Red Sea. The valley contains
some of the deepest lakes in the world.

The largest rift
lake in Africa, Lake
Splitting Africa in two Tanganyika is up to
The western branch of the East African 4,820 ft (1,470 m) deep.
Rift Valley forms the western frontiers of
Uganda, Rwanda, and Tanzania. Sinking The crust beneath Lake
continental crust in the valley floor has Tanganyika is sinking into
created a chain of deep lakes, including the rift. Sediments on the
Lake Tanganyika, the world’s second lake bed are sinking with it.
deepest lake. Molten rock erupting
through the thin, stretched crust has
also formed many volcanoes. As the crust pulls apart it
fractures, creating huge
faults that allow the rock
to slip downwards.

GIANT STEPS
As the eastern side of the Great Rift Valley
pulls away from the western side, huge slabs
of rock sink into the rift. This has created a
series of giant steps in the African landscape
on each side of the valley. Each step is a
block of continental crust that has slipped
down a near-vertical fault, and the fault
forms the steep cliff behind it.

TOWERING CLIFFS
The Torok River cascades over a cliff on the western A heat current rising through
side of the Rift Valley in Kenya. The cliff marks one The continent of Africa is Earth’s deep mantle creates
of the main faults that created the valley. pulling apart, stretching
and thinning the crust an extra-hot mantle plume
above the mantle plume. beneath the rift.

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