Page 67 - Super Earth Encyclopedia
P. 67
“Every year, STATS AND FACTS
Africa gets a The Great Rift Valley is RIFTING DEPTH
one of the few places The two sides of In places, the
valley floor lies
the Rift Valley are
little closer to in the world where a pulling apart at 8,860 ft (2,700 m)
continent is being
below the land
the rate of about
IN THE
pulled apart. In many 28 in (71 cm) on each side. RIFT VALLEY
a century.
splitting into millions of years’ time, CRUST PEOPLE ACTIVE VOLCANOES 30
East Africa will become
an island continent in The continental Fossil remains
crust beneath the
of some of our
two continents.” the Indian Ocean. Rift Valley is five earliest ancestors
times thinner than
have been found
usual for Africa.
in the Rift Valley.
The Great African Rift Blocks of crust The lake fills the
is visible from space sink down fault bottom of the
as a giant scar in the lines into the rift. rift valley.
continent.
The crust
pulls apart. RIFT FORMATION
The continental crust of the rift
zone is being stretched, so it is
thinner than usual. Hot mantle
rock below the thin crust
makes it swell upward, but
the tension has also made it
fracture, creating fault lines.
These allow blocks of crust to
slip downward, creating the
Rift Valley and its deep lakes.
Hot mantle rises
under the crust.
AT A GLANCE
• LOCATION The Y-shaped Rift Valley is in
East Africa, extending from the Afar region in
the north to the mouth of the Zambezi River
in the south FORMIDABLE FORMATIONS
• LENGTH 2,500 miles (4,000 km)
• AGE The rift started opening up 30 million
years ago
•
The opening rift in the crust FORMATION TYPE Continental rift zone
eases pressure on the hot mantle
rock below, allowing some to
melt and form fluid magma.
65
US_064-065_Rift_Valley.indd 65 01/03/17 3:46 pm
