Wednesday, March 15, 2006

Africa coming apart

A Continent Splits Apart

By Axel Bojanowski

Normally new rivers, seas and mountains are born in slow motion. The Afar Triangle near the Horn of Africa is another story. A new ocean is forming there with staggering speed -- at least by geological standards. Africa will eventually lose its horn.

Geologist Dereje Ayalew and his colleagues from Addis Ababa University were amazed --and frightened. They had only just stepped out of their helicopter onto the desert plains of central Ethiopia when the ground began to shake under their feet. The pilot shouted for the scientists to get back to the helicopter. And then it happened: the Earth split open. Crevices began racing toward the researchers like a zipper opening up. After a few seconds, the ground stopped moving, and after they had recovered from their shock, Ayalew and his colleagues realized they had just witnessed history. For the first time ever, human beings were able to witness the first stages in the birth of an ocean.

Normally changes to our geological environment take place almost imperceptibly. A life time is too short to see rivers changing course, mountains rising skywards or valleys opening up. In north-eastern Africa's Afar Triangle, though, recent months have seen hundreds of crevices splitting the desert floor and the ground has slumped by as much as 100 meters (328 feet). At the same time, scientists have observed magma rising from deep below as it begins to form what will eventually become a basalt ocean floor. Geologically speaking, it won't be long until the Red Sea floods the region. The ocean that will then be born will split Africa apart.

The Afar Triangle, which cuts across Ethiopia, Eritrea and Djibouti, is the largest construction site on the planet. Three tectonic plates meet there with the African and Arabic plates drifting apart along two separate fault lines by one centimeter a year. A team of scientists working with Christophe Vigny of the Paris Laboratory of Geology reported on the phenomenon in a 2006 issue of the Journal of Geophysical Research. While the two plates move apart, the ground sinks to make room for the Red Sea and the Gulf of Aden.