MODIS satellite image of the Afar Depression and surrounding regions of the Red Sea, Gulf of Aden, Arabia, and the Horn of Africa.

The Afar Depression (also called the Danakil Depression or the Afar Triangle) is a geological depression in the Horn of Africa, where it overlaps Eritrea, the Afar Region of Ethiopia, and Djibouti. Afar, especially the Middle Awash, Gona, and Hadar, is well known as one of the cradles of hominids: the first for many fossil hominid discoveries, the second for the worlds oldest stone tools, and the last for Lucy, the fossilized specimen of Australopithecus afarensis. The Afar Depression includes the lowest point in Africa, Lake Asal (−155 meters {−500 ft}). The climate varies from around 25 °C (77 °F) during the rainy season (September-March) to 48 °C (118°F) during the dry season (March-September). It is one of the hottest places year-round anywhere on Earth. Only the Awash River flows into the depression, where it ends in a chain of lakes that increase in salinity. Ash plumes on Kamchatka Peninsula, eastern Russia MODIS (Moderate-resolution Imaging Spectroradiometer) is a payload scientific instrument launched into Earth orbit by NASA in 1999 on board the Terra (EOS AM) Satellite, and in 2002 on board the Aqua (EOS PM) satellite. ... Location of the Red Sea The Red Sea is an inlet of the Indian Ocean between Africa and Asia. ... The Gulf of Aden is located in the Indian Ocean between Yemen on the south coast of the Arabian Peninsula and Somaliland in Africa. ... The Arabian Peninsula The Arabian Peninsula is a mainly desert peninsula in Southwest Asia at the junction of Africa and Asia and an important part of the greater Middle East. ... Nations of the Horn of Africa. ... Nations of the Horn of Africa. ... Map of Ethiopia highlighting the Afar region. ... The Middle Awash is an archaeological site along the Awash River in Ethiopias Afar Depression. ... Hadar is a site on the Awash River in Ethiopia, in the Afar Triangle. ... A hominid is any member of the biological family Hominidae (the great apes), including the extinct and extant humans, chimpanzees, gorillas, and orangutans. ... Binomial name †Australopithecus afarensis Johanson & White, 1978 Australopithecus afarensis is an extinct hominid which lived between 3. ... Lake Assal seen from space Lake Karum in the Ethiopian portion of the northern Afar Depression is also sometimes called Lake Assal. ... The Awash (sometimes spelled Hawash) is a major river of Ethiopia. ...

Environment

The lowlands of the Afar Depression are dominated by heat and drought. There is no rain for most of the year; yearly rainfall averages range from 100 to 200 millimeters (4 to 7 in), with less rain falling closer to the coast. The Awash River, flowing north-eastward through southern Afar, provides a narrow green belt and enables life for the Afars, the nomadic people living in the Danakil desert, and for all other flora and fauna in the area. About 128 kilometers (79 miles) from the Red Sea, the Awash ends in a chain of salt lakes, where its water evaporates as fast as it is supplied. About 1200 kilometers² (463 miles²) of the Afar Depression is covered by salt, and salt mining is still a major source of income for many Afar tribes. The Awash (sometimes spelled Hawash) is a major river of Ethiopia. ... Afar is one of the nine ethnic divisions (kililoch) of Ethiopia. ... Location of the Red Sea The Red Sea is an inlet of the Indian Ocean between Africa and Asia. ... A magnified crystal of a salt (halite/sodium chloride) Salt covering the floor of Bad Water in Death Valley, CA, the lowest point in the US. A salt, in chemistry, is any ionic compound composed of cations (positively charged ions) and anions (negative ions) so that the product is neutral...

Perspective view of the Afar depression and environs, generated by draping a Landsat image over a Digital elevation model. Image generated by Allison Thurmond.

The Afar Depression biome is characterized as desert scrubland. Vegetation is mostly confined to drought-resistant plants such as small trees (e.g. species of the dragon tree), shrubs, and grasses. Wildlife includes many herbivores including Grevy's Zebra, Soemmering’s Gazelle, Oryx Beisa and, notably, the last viable population of African wild ass (Equus africanus somalicus). Birds include the ostrich, the endemic Archer's lark (Heteromirafra archeri), the Secretary Bird, Arabian and Kori bustards, Abyssinian Roller and Crested Francolin. In the southern part of the plain, in Ethiopia, lies the Mille-Sardo Wildlife Reserve (established 1973). Many fossils have been found in the Awash region, not only hominids but also elephantoids, crocodiles and hippopotamus. The Landsat program is the longest running enterprise for acqusition of imagery of Earth from space. ... A digital elevation model (DEM) is a representation of the topography of the Earth in digital format, that is, by coordinates and numerical descriptions of altitude. ... In ecology, a biome is a major regional group of distinctive plant and animal communities best adapted to the regions physical natural environment, latitude, elevation, and terrain. ... In isolation, Hawaiis Silverswords have adapted to xeric microclimates within volcanic craters, trapping and channeling dew and protecting leaves with reflective hairs. ... Species See article Dracaena is a genus of about 40 species of trees and succulent shrubs in the family Agavaceae, or, according to some treatments, separated (with Cordyline) into a family of their own, Dracaenaceae. ... A deer and two fawns feeding on some foliage A herbivore is often defined as any organism that eats only plants[1]. By that definition, many fungi, some bacteria, many animals, about 1% of flowering plants and some protists can be considered herbivores. ... Binomial name Equus grevyi Oustalet, 1882 Distribution of Equus grevyi The Grevys Zebra (Equus grevyi), sometimes known as the Imperial Zebra, is the largest species of zebra. ... Species Several, see text A gazelle is an antelope of the genus Gazella. ... Binomial name Oryx beisa Rüppell, 1835 The East African Oryx (Oryx beisa, also known as the Beisa Oryx) found in steppe and semi-desert throughout the Horn of Africa and in parts of Tanzania. ... Binomial name Equus asinus Linnaeus, 1758 For other uses, see Donkey (disambiguation). ... Binomial name Struthio camelus Linnaeus, 1758 The present-day distribution of ostriches. ... In biology and ecology endemic means exclusively native to a place or biota, in contrast to cosmopolitan or introduced. ... Genera Mirafra Pinarocorys Heteromirafra Certhilauda Chersomanes Eremopterix Ammomanes Alaemon Ramphocoris Melanocorypha Calandrella Spizocorys Eremalauda Chersophilus Galerida Pseudalaemon Lullula Alauda Eremophila Larks are passerine birds of the predominantly Old World family Alaudidae. ... Binomial name Sagittarius serpentarius (Miller,JF, 1779) The Secretary Bird, Sagittarius serpentarius, is an extraordinary member of the bird of prey family. ... Genera See text. ... Binomial name Coracias abyssinica Hermann, 1783 The Abyssinian Roller, Coracias abyssinica, is a member of the roller family of birds which breeds across tropical Africa in a belt south of the Sahara. ... Species 41, see text The francolins are the species of bird in the genus Francolinus of the pheasant family, Phasianidae. ... A hominid is any member of the biological family Hominidae (the great apes), including the extinct and extant humans, chimpanzees, gorillas, and orangutans. ...

Geology

Simplified geologic map of the Afar Depression, after Berhane and Abdelsalam (2005).

Location of the depression and local fault lines

The Afar Depression is a plate tectonic triple junction where the spreading ridges that are forming the Red Sea and the Gulf of Aden emerge on land and meet the East African Rift. The central meeting place for these three pieces of Earth's crust is around Lake Abbe. The Afar Depression is one of two places on Earth where a mid-ocean ridge can be studied on land, the other being Iceland. Image File history File links Map of East Africa showing some of the historically active volcanoes(red triangles) and the Afar Triangle (shaded, center) -- a triple junction where three plates are pulling away from one another: the Arabian Plate, and the two parts of the African Plate (the Nubian and... Image File history File links Map of East Africa showing some of the historically active volcanoes(red triangles) and the Afar Triangle (shaded, center) -- a triple junction where three plates are pulling away from one another: the Arabian Plate, and the two parts of the African Plate (the Nubian and... The tectonic plates of the world were mapped in the second half of the 20th century. ... A triple junction is the point where three tectonic plates diverge. ... Location of the Red Sea The Red Sea is an inlet of the Indian Ocean between Africa and Asia. ... The Gulf of Aden is located in the Indian Ocean between Yemen on the south coast of the Arabian Peninsula and Somaliland in Africa. ... Northern section of the Great Rift Valley. ... Lake Abbe or Lake Abhe Bad is a salt lake, lying on the Ethiopia-Djibouti border. ... A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. ...

The Afar, a nascent seafloor spreading center, is slowly rifting apart at a rate of 1–2 centimeters (0.3–0.8 in) per year. The immediate consequence of this is that there are (as of late 2005) a continuous sequence of earthquakes, fissures hundreds of metres long and deep appearing in the ground, and the valley floor sinking as much as 100 metres. Between September and October 2005, 163 earthquakes of magnitudes greater than 3.9 and a volcanic eruption occurred within the Afar rift. 2.5 cubic kilometers of molten rock was injected into the plate along a dyke between depths of 2 and 9 km, forcing open an 8 meter wide gap on the surface.^[1] Age of oceanic crust. ... 2005 is a common year starting on Saturday of the Gregorian calendar. ... The cubic meter (symbol m³) is the SI derived unit of volume. ... A dike in geology refers to a tabular intrusive igneous body. ...

Over millions of years, geologists expect the Red Sea to erode through the highlands surrounding the Afar Depression and flood the valley. In about 10 million years, geologists predict that the whole 6,000 km length of the East African Rift will be submerged, forming a new sea as large as the Red Sea is now. At that point, Africa will have lost its horn.^[2] Location of the Red Sea The Red Sea is an inlet of the Indian Ocean between Africa and Asia. ...

The floor of the Afar Depression is composed of lava, mostly basalt. One of Earth's great active volcanoes, Erta Ale, is found here. The Afar Depression and Triple Junction also mark the location of a mantle plume, a great uprising of mantle that melts to yield basalt as it approaches the surface (other mantle plumes can be found beneath the great volcanic islands of Iceland, Hawaii and Galapagos; also a mantle plume is responsible for Yellowstone in the USA). Look up lava, Aa, pahoehoe in Wiktionary, the free dictionary. ... Basalt Columnar basalt at Sheepeater Cliff in Yellowstone Basalt (IPA: ) is a common gray to black volcanic rock. ... Erta Ale is an active shield volcano in Ethiopia, known for its long-standing lava lake activity. ... A lava lamp illustrates the basic concept of a mantle plume. ... Earth cutaway from core to exosphere. ... This article or section does not cite its references or sources. ... NASA Satellite photo of the Galápagos archipelago. ... Yellowstone National Park is a U.S. National Park located in the states of Idaho, Montana, and Wyoming. ...

References

1. ^ Wright, T.J.; et al. (July 2006). "Magma-maintained rift segmentation at continental rupture in the 2005 Afar dyking episode". Nature 442: 291-294. DOI:10.1038/nature04978. 
2. ^ Bojanowski 2006

• Alebachew Beyene and Mohamed G. Abdelsalam, 2005. "Tectonics of the Afar Depression: A review and synthesis." Journal of African Earth Sciences, Volume 41, Issues 1-2, pp 41-59
• Kloos, Helmut (1982) 'Development, drought and famine in the Awash valley of Ethiopia', African Studies Review, vol. 25, no. 4, p. 21-48.
• [World Wildlife Fund] (2001) 'Ethiopian xeric grasslands and shrublands (AT1305)' online version.
• Bojanowski, Axel. "A Continent Splits Apart", Spiegel Online, March 15, 2006. Retrieved on 2006-03-16. Includes a photo essay of the region and its geologic changes.

A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... For the Manfred Mann album, see 2006 (album). ... March 16 is the 75th day of the year in the Gregorian Calendar (76th in leap years). ...

External links

• Another view from space.
• Danakalia
• Photos of Erta Ale
• Hotsprings at Dallol
• The Ethiopian state of Afar