The Danakil Alps are a highland region in

Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...

and

Eritrea Eritrea, officially the State of Eritrea, is a country in the Horn of Africa region of East Africa, with its capital and largest city being Asmara. It is bordered by Ethiopia in the Eritrea–Ethiopia border, south, Sudan in the west, and Dj ...

with peaks over 1000 metres in height and a width varying between 40 and 70 kilometres. The area is known in the

Afar language Afar is an Afroasiatic language belonging to the Cushitic branch, primarily spoken by the Afar people, native to parts of Djibouti, Eritrea and Ethiopia. It is an official language in Ethiopia; and a national language in Djibouti and Eritre ...

as Arrata. The alps lie along the southern

Red Sea The Red Sea is a sea inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab-el-Mandeb Strait and the Gulf of Aden. To its north lie the Sinai Peninsula, the Gulf of Aqaba, and th ...

to the east of the Danakil Depression and separate it from the sea. The alps are asymmetric in cross-section with a comparatively gentle rift escarpment facing the Red Sea and intense

normal fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

ing on the inland side. In the northern part of the alps the basement rock is less elevated and there are many volcanic edifices, such as those forming the Nabro Volcanic Range. The largest of the Nabro Volcanic Range edifices are the Mallahle, Nabro, and Dubbi. The volcanic range extends northwestward to the Red Sea, ending with the Kod Ali volcano offshore. The Danakil Alps have been cut off from the sea since the late

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

Composition

Geologically these highlands are described as a horst and are sometimes referred to as the Danakil Horst or Danakil Block. They were formed by geological faulting which has occurred since the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

epoch. There is

Precambrian The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of t ...

basement A basement is any Storey, floor of a building that is not above the grade plane. Especially in residential buildings, it often is used as a utility space for a building, where such items as the Furnace (house heating), furnace, water heating, ...

rock underlying the region and in coastal Eritrea Precambrian and

Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...

rocks are exposed. The Antalo Limestone in the Danakil Alps is unusually thick for the

Horn of Africa The Horn of Africa (HoA), also known as the Somali Peninsula, is a large peninsula and geopolitical region in East Africa.Robert Stock, ''Africa South of the Sahara, Second Edition: A Geographical Interpretation'', (The Guilford Press; 2004), ...

, being at least in depth, implying that the area acted as a

drainage basin A drainage basin is an area of land in which all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...

before the uplift and break up of the Afro-Arabian continent. The basement rock of the alps has become overlaid with

flood basalt A flood basalt (or plateau basalt) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot (geolo ...

since the

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

epoch. The pre-rift

stratigraphic section A stratigraphic section is a sequence of layers of rocks in the order they were deposited. It is based on the principle of original horizontality, which states that layers of sediment are originally deposited horizontally under the action of ...

in the Danakil Alps exceeds , greater than that to the north, reflecting the development of the Indian Ocean margin during the Mesozoic.

Development

About 20 million years ago the Afar rift zone opened up. This resulted in the alps breaking away from the Ethiopian plateau to which they had previously been attached and drifting to the east/northeast. Paleomagnetic measurements indicate that, beginning in the early Miocene, the alps rotated counterclockwise by 20–30 degrees from their original position over a period of 11 million years as a result of the opening of the Red Sea. During the last million years, spreading has continued to propagate west from the

Gulf of Aden The Gulf of Aden (; ) is a deepwater gulf of the Indian Ocean between Yemen to the north, the Arabian Sea to the east, Djibouti to the west, and the Guardafui Channel, the Socotra Archipelago, Puntland in Somalia and Somaliland to the south. ...

into the Gulf of Tadjoura and into the

Afar Region The Afar Region (; ; ), formerly known as Region 2, is a Regions of Ethiopia, regional state in northeastern Ethiopia and the homeland of the Afar people. Its capital is the planned city of Semera, which lies on the paved Awash, Ethiopia, Awash� ...

via the subaerially exposed Asal–Ghoubbet rift. This active plate boundary continues along the west side of the Danakil Block, and links to the Red Sea at the Gulf of Zula. Stretching factors of the

continental crust Continental crust is the layer of igneous, metamorphic, and sedimentary rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as '' continental shelves''. This layer is sometimes called '' si ...

in the Danakil Alps are estimated to be up to β = ~2.5.

References

{{Regions of Africa Mountain ranges of Africa Ethiopian Highlands Horsts (geology)

Composition

Development

See also

References