Tarso Emi Chi (tarso: "gentle mountain, high plateau"; emi: "large mountain"; named by the

Toubou The Toubou or Tubu (from Old Tebu, meaning "rock people") are an ethnic group native to the Tibesti Mountains that inhabit the central Sahara in northern Chad, southern Libya and northeastern Niger. They live either as herders and nomads or as ...

) is a volcano in

Chad Chad (; ar, تشاد , ; french: Tchad, ), officially the Republic of Chad, '; ) is a landlocked country at the crossroads of North and Central Africa. It is bordered by Libya to the north, Sudan to the east, the Central African Republic ...

. Tarso Emi Chi is part of the

Tibesti Mountains The Tibesti Mountains are a mountain range in the central Sahara, primarily located in the extreme north of Chad, with a small portion located in southern Libya. The highest peak in the range, Emi Koussi, lies to the south at a height of and i ...

, a group of volcanic mountains that cover a surface area of and reach an elevation of . The mountains consist of both a

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, 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 the ...

crystalline rocks and volcanic rocks. The volcano consists of a

lava plateau A volcanic plateau is a plateau produced by volcanism, volcanic activity. There are two main types: lava plateaus and pyroclastic plateaus. Lava plateau Lava plateaus are formed by highly fluid basaltic lava during numerous successive erup ...

that originated in a number of vents, which form a number of volcanic cones. It covers a surface of about in the northeastern Tibesti mountains, with a steep drop towards the east and the north and gentler slopes in the south and west. Summits in the volcano include Boubou, Chebedo, Godoon, Kazena Lulli, Kégueur Tédi, Mouskorbé, Tarso Adar, Tarso Aozi, Tarso Chididemi, Tarso Goziydi, Tarso Kozen and Tarso Toudougou. Of these Mouskorbé reaches a height of . Tarso Emi Chi has erupted a number of volcanic series such as the "black series" and the "white series", which consist of

basaltic andesite Basaltic andesite is a volcanic rock that is intermediate in composition between basalt and andesite. It is composed predominantly of augite and plagioclase. Basaltic andesite can be found in volcanoes around the world, including in Central Ameri ...

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...

and

trachyte Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava enriched with silica and al ...

Syenite Syenite is a coarse-grained intrusive igneous rock with a general composition similar to that of granite, but deficient in quartz, which, if present at all, occurs in relatively small concentrations (< 5%). Some syenites contain larger proport ...

intrusion In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

s have been found as well, the black series consist mainly of

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

. The "white series" is usually more heavily eroded than the "black series". There is no evidence of historical eruptions at Tarso Emi Chi, but volcanic products overlie

diatom A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev ...

beds of former lakes.

Vegetation, ice and water

Block glaciers developed on Mouskorbe, the largest of which is long on the south flank and ends at elevation. There is widespread evidence of

nivation Nivation is the set of geomorphic processes associated with snow patches. The primary processes are mass wasting and the freeze and thaw cycle, in which fallen snow gets compacted into firn or névé. The importance of the processes covered by the ...

landforms on Mouskorbe above and especially above . Presently, precipitation at Mouskorbe is about . Former lakes in Tarso Emi Chi were inhabited by

snail A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gastro ...

s such as '' Euconulus fulvus'', '' Limnea trunculata'', '' Succinea pfeifferi'' and ''

Zonitoides nitidus ''Zonitoides nitidus'' (sometimes ''Zonitoides nitida'') is a species of small, air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the family Gastrodontidae. ''Zonitoides nitidus'' is the type species of the genus '' Zonito ...

'', as well as by

grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns an ...

es and

reed Reed or Reeds may refer to: Science, technology, biology, and medicine * Reed bird (disambiguation) * Reed pen, writing implement in use since ancient times * Reed (plant), one of several tall, grass-like wetland plants of the order Poales * ...

s. Further, Mouskorbe was part of the Kufrah paleoriver

watershed Watershed is a hydrological term, which has been adopted in other fields in a more or less figurative sense. It may refer to: Hydrology * Drainage divide, the line that separates neighbouring drainage basins * Drainage basin, called a "watershe ...

; drainages to the east are very steep, north are steep and step-like and drainages to the west are gentler but have still developed deep canyons. Presently,

acacia ''Acacia'', commonly known as the wattles or acacias, is a large genus of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa and Australasia. The genus na ...

s grow up to elevations of .

References

Sources

* * * * {{refend Pleistocene volcanoes Tibesti Mountains Volcanoes of Chad