Tarso Toh (also known as Tarso Toon or Tarson Tôh) is a

volcanic field A volcanic field is an area of Earth's crust that is prone to localized volcanic activity. The type and number of volcanoes required to be called a "field" is not well-defined. Volcanic fields usually consist of clusters of up to 100 volcanoes ...

located 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 ...

, north of Tarso Toussidé volcano. It fills valleys and plains over an area of 80 km in east-west direction and 20–30 km in north-south direction. It contains 150

scoria cone Scoria is a pyroclastic, highly vesicular, dark-colored volcanic rock that was ejected from a volcano as a molten blob and cooled in the air to form discrete grains or clasts.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ''G ...

s and two

maar A maar is a broad, low-relief volcanic crater caused by a phreatomagmatic eruption (an explosion which occurs when groundwater comes into contact with hot lava or magma). A maar characteristically fills with water to form a relatively shallow ...

s. Tarso Toh is a volcanic plateau and has lateral dimensions of , resulting in a surface area of about . It rises to elevations of above sea level and above the surrounding terrain. The plateau encompasses about 150 separate volcanoes, some of which are found in remnants. Some

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or und ...

s at Tarso Toh have reached large distances. Part of the field is the Begour

crater Crater may refer to: Landforms *Impact crater, a depression caused by two celestial bodies impacting each other, such as a meteorite hitting a planet *Explosion crater, a hole formed in the ground produced by an explosion near or below the surfac ...

. It is about wide and is mostly dry with the exception of several small ponds and a ring of

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 ...

- and

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

-containing sediments which forms a ring terrace inside the crater.

Radiocarbon dating Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The method was dev ...

has yielded ages of 8,300 ± 300 years ago on sediments within Begour, and Tarso Toh is considered to be a

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...

volcano. The

Tibesti 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 is ...

features several different rock formations. A crystalline basement is covered by

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

s. These were subject to deformation and later overprinted by volcanic rocks. This basement is about 500-600 million years old. The recent volcanism has been explained with the existence of a

mantle plume A mantle plume is a proposed mechanism of convection within the Earth's mantle, hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hot ...

beneath Tibesti.

Climate and biota

The climate of the region is arid but in general there is more precipitation than in the surrounding desert, which results in the formation of

wadi Wadi ( ar, وَادِي, wādī), alternatively ''wād'' ( ar, وَاد), North African Arabic Oued, is the Arabic term traditionally referring to a valley. In some instances, it may refer to a wet (ephemeral) riverbed that contains water onl ...

s. Temperatures at

Zouar Zouar ( ar, زوار) is a town in the Tibesti Ouest department of the Tibesti region in northern Chad, located in an oasis in the Tibesti Mountains. Prior to 2008 it was in the Tibesti Department of the former Bourkou-Ennedi-Tibesti region The ...

( elevation) range from in winter to in summer; at high altitudes freezing temperatures may be common. Vegetation is scarce; in the proximity of waters some

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 and grasses can be found. A number of mollusc shells have been found in the Begour sediments, such as '' Anisus costulatus'', '' Anisus dallonii'', ''

Biomphalaria pfeifferi ''Biomphalaria pfeifferi'' is a species of air-breathing freshwater snail, an aquatic animal pulmonate gastropod mollusk in the family Planorbidae, the ram's horn snails. This snail is a medically important pest, because of transferring the ...

'', ''

Bulinus truncatus ''Bulinus truncatus'' is a species of air-breathing freshwater snail with a sinistral shell, an aquatic pulmonate gastropod mollusk in the subfamily Bulininae of the family Bulinidae, the ram's horn snails and the like. MolluscaBase eds. (2 ...

'', ''

Gastrocopta klunzingeri ''Gastrocopta klunzingeri'' is a species of gastropods belonging to the family Gastrocoptidae Gastrocoptidae is a family of minute, air-breathing land snails, terrestrial pulmonate gastropod molluscs in the superfamily Pupilloidea.Philip ...

,'' '' Lymnaea natalensis'', ''

Melanoides tuberculata The red-rimmed melania (''Melanoides tuberculata''), also known as Malayan livebearing snails or Malayan/Malaysian trumpet snails (often abbreviated to MTS) by aquarists, is a species of freshwater snail with an operculum, a parthenogenetic, a ...

'', ''

Pisidium ''Pisidium'' is a genus of very small or minute freshwater clams known as pill clams or pea clams, aquatic bivalve molluscs in the family Sphaeriidae, the pea clams and fingernail clams. In some bivalve classification systems, the family Spha ...

sp.'' ''

Segmentina angusta ''Segmentina'' is a genus of very small, air-breathing, freshwater snails, aquatic gastropod mollusks or micromollusks in the family Planorbidae, the ramshorn snails. Albrecht et al. (2007)Albrecht C., Kuhn K. & Streit B. (2007). "A molecul ...

'', ''

Succinea ''Succinea'', common name the amber snails, is a large genus of small, air-breathing land snails, terrestrial pulmonate gastropod molluscs in the family Succineidae. MolluscaBase eds. (2021). MolluscaBase. Succinea Draparnaud, 1801. Access ...

sp.'', '' Thapsia vestii'' and ''

Zootecus insularis ''Zootecus insularis'' is a species of gastropods belonging to the family Achatinidae Achatinidae (New Latin, from Greek "''agate''") is a family of medium to large sized tropical land snails, terrestrial pulmonate gastropod mollusks from Afri ...

'', although their identification is now always clear.Sparks and Grove 1961, p.360

References

Sources

* * * * {{DEFAULTSORT:Toh, Tarso Tibesti Mountains Mountains of Chad Volcanoes of Chad Maars of Chad Volcanic fields

Climate and biota

See also

References

Sources