Birth of an Ocean: The Evolution of Ethiopia's Afar Depression
Formation of an ocean is a rare event, one few scientists have ever witnessed. Yet this geophysical nativity is unfolding today in one of the hottest and most inhospitable corners of the globe. Visit the site in safety through this extraordinary photographic essay
Credits: Eitan Haddock
MIRAGE OR HALLUCINATION? Most years the greatest concern for the Afar people is finding adequate water. But the rains were unusually heavy in late 2006, and many of the salt fields remained flooded throughout my visit in January 2007. This unusual environmental circumstance afforded one of the most lasting impressions of my visit to Afar: as the camel caravans waded through the floodwaters, they appeared from a distance as a surreal montage of the present and future of this ocean floor in the making.
SALT OF THE EARTH The closest places to sell or exchange the salt are located in the Ethiopian highlands to the west--about a six days' walk for the camel caravans used to transport this unlikely export.
SALT OF THE EARTH Salty traces of past deluges give the modern people of Afar a modest means to benefit from their baked and barren homeland. These nomadic herders collect the salt by hand, wielding wooden stakes and hatchets to break the thick layers into manageable blocks.
FATEFUL FLOODS In other areas, alternating layers of salt and reddish marine sediment are visible in eroded canyon walls.
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FATEFUL FLOODS When sea level dropped and Afar was once again cut off from the sea, the floodwaters evaporated. Wind and water sculpted the salty traces of these past inundations over the ensuing millennia, sometimes carving bizarre formations called salt mushrooms.
FATEFUL FLOODS The salt sculptures on the opposite page and others that decorate Afar serve as a reminder that the birth of an ocean is not a singular event but rather an ongoing saga. During the 30 million years this region has been stretching thin, global sea level has fluctuated, at times filling Afar with seawater. Most recently, about 80,000 years ago, the waters of the Red Sea rose high enough to breech the low hills east of Afar, carving deep canyons as they flooded the lowlands.
POISON OR ELIXIR? Near reddish pools of bubbling-hot, iron-rich water, the strong odor of hydrocarbon is a telltale sign of danger. Animals sometimes stop for a drink--not realizing it will be their last. I saw several ill-fated birds swirling in the scalding pools. But I was comforted by the irony that one organism's poison is another's elixir. The same emanations that can kill birds, insects and mammals also nourish complex communities of microbes, which thrive in many of Dallol's acidic waters. Not surprisingly, these terrestrial hot-springs communities bear striking similarities to their counterparts along submerged mid-ocean ridges.
LETHAL FUMES The surreal landscape of the Dallol crater results as rain-water percolates deep underground, heats up as it contacts hot magma and rises to the surface through thick layers of salt, dissolving the salt as it travels. Recrystallization of the salt at ground level can sculpt massive structures (
left) or formations as delicate as an eggshell ( right) . But the beauty of the sculptures can be deceiving: toxic vapors emanating from these so-called aeration mouths are yet another contributorto Afar's devilish reputation--and often require visitors to wear gas masks. More than once a surge of the ominous gas forced me to stop shooting photographs and don my mask for safety. Eitan Haddok Advertisement
HELLISH HEAT The mineral sulfur produces the lemon-yellow color in this earthly palette (
left); blended with the signature red of oxidized iron, the sulfur stains turn orange ( center). Only a few steps away from this vivid scene are drab, desiccated reminders of a hot spring's ephemeral nature ( right). When an earthquake or other natural process clogs a vent's buried conduits, its minerals can lose their florid flush within a year. Eitan Haddok
HELLISH HEAT One hundred kilometers north of Erta Ale, near the Eritrea border, is the Dallol crater. There molten magma simmering below the surface fuels a vast plumbing network of superheated water. The result is a 1.6-kilometer-wide field of hydrothermal vents, geysers and hot springs that call to mind the similar but more accessible environment in Yellowstone National Park in the western U.S.
LAKE OF LAVA Lava emerging from cracks in the lake is particularly spectacular at night, when the sight evokes the phantoms of local lore.
LAKE OF LAVA Most of the Afar people do not approach the volcano, because it is thought to harbor evil spirits. Seeing an Afar warrior on the volcano's summit is unusual; this man, Ibrahim, was my guide.
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LAKE OF LAVA Typically, though, blocks of basalt float like icebergs on the fiery liquid rock, which reaches 1,200 degrees C (2,190 degrees F).
LAKE OF LAVA Atop Erta Ale is one of the earth's few quasi-permanent lava lakes. The flux of heat from the earth's interior is rarely sufficient to keep rock molten under the cooling effect of the atmosphere. Even on Erta Ale the heat sometimes slackens enough so that portions of the lake surface "freeze" into a black crust.
RISING ABOVE The highest point in sunken Afar is Erta Ale, or "smoking mountain" in the language of the local people. Erta Ale is the northernmost volcano in a long chain that follows the so-called East African Rift.
This rift is the not yet submerged equivalent of mid-ocean ridges--chains of under-sea volcanoes that produce new seafloor. Indeed, Erta Ale spews the same kind of basaltic lava that erupts at mid-ocean ridges; past expulsions have covered the surrounding plain with so much fresh basalt that vegetation struggles to take hold. Eitan Haddok
GHOSTLY SALT DEPOSITS Near Afdera volcano testify to ancient inundations in Ethiopia's Afar region. In the past 200,000 years the Red Sea flooded Afar's lowlands at least three times; the salt stayed behind as the seawater evaporated. One day the ersatz seascape will likely become the real thing.
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AFAR DEPRESSION This area marks the north end of the East African Rift, a3,500-kilometer-long zone of tectonic turmoil that is tearing the continent in two (
arrows on globe) The detail shows a segment of the depression. Kevin Hand Advertisement |