page_title: Geography of Ethiopia
section_title: Geology
hierarchical_section_title: Geography of Ethiopia / Geology
caption_attribution_description: Nabro Volcano (upper right, in Eritrea) and Mallahle Volcano (lower left, in Ethiopia). SRTM Colored Height and Shaded Relief image.
context_page_description: Ethiopia is located in the Horn of Africa. It is bordered by Eritrea to the north, Djibouti and Somalia to the east, Sudan and South Sudan to the west, and Kenya to the south. Ethiopia has a high central plateau that varies from 1,290 to 3,000 m above sea level, with the highest mountain reaching 4,533 m.
  Elevation is generally highest just before the point of descent to the Great Rift Valley, which splits the plateau diagonally. A number of rivers cross the plateau; notably the Blue Nile rising from Lake Tana. The plateau gradually slopes to the lowlands of the Sudan on the west and the Somali-inhabited plains to the east. Ethiopia's westermost locality is Pibor River opposite the Sudanese village of Denjok. Its eastermost locality lies along the eastern border of Dollo Zone opposite Puntland and Galmudug states.
context_section_description: The East African tableland is continued into Ethiopia. A pioneering study of the geology of Ethiopia was W. T. Blanford's work in 1870. More recent work has focused on the Afar Depression, due to its importance as one of two places on Earth where a mid-ocean ridge can be studied on land (the other is Iceland).
  The following formations are represented:
  Sedimentary and metamorphic
  Recent: Coral, alluvium, sand
  Tertiary: Limestones of Harrar
  Jurassic: Antalo Limestones
  Triassic: Adigrat Sandstones
  Archaean: Gneisses, schists, slaty rocks
  Igneous
  Recent: Aden Volcanic Series
  Tertiary, Cretaceous: Magdala group
  Jurassic: Ashangi group
  Archaean.– The metamorphic rocks compose the main mass of the tableland, and are exposed in every deep valley in Tigre and along the valley of the Blue Nile. Micaschists form the prevalent rocks. Hornblende schists also occur and a compact felspathic rock in the Suris defile. The foliae of the schists strike north and south.
  Triassic.– In the region of Adigrat the metamorphic rocks are invariably overlain by white and brown sandstones, unfossiliferous, and attaining a maximum thickness of 300 m. They are overlain by the fossiliferous limestones of the Antalo group. Around Chelga and Adigrat coal-bearing beds occur, which Blanford suggests may be of the same age as the coal-bearing strata of India. The Adigrat Sandstone possibly represents some portion of the Karoo System of South Africa.
  Jurassic.– The fossiliferous Antalo Limestones are generally horizontal, but are in places much disturbed when interstratified with Mekelle Dolerite. The fossils are all characteristic Oolite forms and include species of Hemicidaris, Pholadomya, Ceromya, Trigonia and Alaria.
  Igneous Rocks.– Above a height of 2,400 m (7,900 ft) the country consists of bedded traps belonging to two distinct and unconformable groups. The lower (Ashangi group) consists of basalts and dolerites often amygdaloidal. Their relation to the Antalo limestones is uncertain, but Blanford considers them to be not later in age than the Oolite. The upper (Magdala group) contains much trachytic rock of considerable thickness, lying perfectly horizontally, and giving rise to a series of terraced ridges characteristic of central Ethiopia. They are interbedded with unfossiliferous sandstones and shales.
  Of more recent date (probably Tertiary) are some igneous rocks, rich in alkalis, occurring in certain localities in southern Ethiopia. Of still more recent date are the basalts and ashes west of Massawa and around Annesley Bay and known as the Aden Volcanic Series. With regard to the older igneous rocks, the enormous amount they have suffered from denudation is a prominent feature. They have been worn into deep and narrow ravines, sometimes to a depth of 1,000 to 1,200 m (3,300 to 3,900 ft).
caption: False-color topographical relief image of Nabro caldera (top; in Eritrea) next to the Mallahle volcanic caldera, then Mount Sarkali with the smaller Sork Ale caldera in the bottom right – SRTM colored height and shaded relief.[1]
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