"but they are also highly variable from year to year. Indeed, the Tibesti can see seven to eight years pass between storms. In the south of the range, this variation is largely due to oscillations of the Intertropical Convergence Zone (ITCZ), which steadily moves northward toward Northern Chad from November until August, accompanied by the humid monsoonal air. Normally, the ITCZ repels the Harmattan, a dry trade wind that blows south-west from the Sahara Desert, and brings rainfall to southern Tibesti. However, sometimes the front retires early, before reaching the Tibesti, resulting one or more years of drought. In the"
". Such a large size, relative to its catchment, has raised the question of where this water came from. The formation of such a lake during the glacial maximum was probably dependent on orographic precipitation transported by the subtropical jet stream. The Tibesti mountains are part of a volcanic province that reaches from Libya into Chad and covers a total surface area of about . The Tibesti Mountains have been volcanically active since the late Cenozoic, with one old volcanic unit being dated to 17 million years ago. While all the higher peaks are volcanoes, not all of Tibesti is"
"nearby, on the other side of the border. The average elevation of the Tibesti Mountains is about ; sixty percent of its area exceeds in elevation. The range includes five shield volcanoes whose diameter can reach , with broad bases and the steepest peaks topped with large craters: Emi Koussi; Tarso Toon, which rises above sea level; Tarso Voon; Tarso Yega; and Tarso Toussidé, which culminates in the peak of the same name. Tarso Yega has the largest crater, with a diameter of and a depth of approximately , while Tarso Voon has the deepest crater, with a depth of"
"of the Tibesti exceed in height. These mountains are formed by a group of volcanoes that grew on top of a large dome of Earth's surface. Volcanism there is poorly studied, as the region is remote and access difficult for political reasons. According to historical reports, the Tibu people lived in its summit caldera and in artificial caves. In the Tedaga language, ""Emi"" means ""mountains"", ""massif"". Emi Koussi rises to a height of on the southern side of the volcano, towering above the surrounding terrain. It is considered by some astronauts to be the most recognizable landmark on Earth, as"
"Tibesti Mountains are a large area of tectonic uplift that, according to contemporary theory, resulted from a mantle plume in the craton of the African lithosphere, which is about thick. This tectonic uplift may have been accompanied by the opening, and subsequent closure via subduction, of a rift zone. The heart of the Tibesti is composed of schist, basalt and diorite of the Ediacaran period, one of six exposures of Precambrian crystalline rock in North Africa. These are overlaid by sandstone of the Paleozoic era, while the peaks consist of volcanic rock. The continental hotspot activity began as early as"
"of the range is striated by a network of dry valleys with the north- and east- facing slopes silted by the prevailing winds. After the typically violent rains, these slopes form ephemeral streams and flora. The southwest slopes in the south and west of the mountain range have a gentle rise, while the northern slope of the range is a cliff overlooking the vast Libyan desert pavement known as the Sarir Tibesti. Five rivers in the northern half of the Tibesti Mountains flow to Libya and are part of the Mediterranean Basin, while the southern half belongs to the endorheic"
"the caldera. The mountain was constructed over a basement of Precambrian schists. The well known Soborom Solfataric field is the largest in the Tibesti Mountains, it is located about 5 km west of the summit rim. The active fumaroles, mudpots and hot springs are visited by the people of the Tibesti for medical purposes. Tarso Voon The Tarso Voon is a high stratovolcano in the north of the Republic of Chad. It is located in the western center of the Tibesti Mountains. The summit of the mountain is dominated by the 14 x 18 km relatively flat caldera. Extensive basaltic"
"Toussidé, respectively. Another volcano in Tibesti is Emi Koussi, which is the highest mountain of the Tibesti and of the entire Sahara region. The volcano Tarso Toh lies northwest of Toussidé, the Botoum and Botoudoma/Petit Botoum rhyolite extrusions are located south of Trou au Natron. The origin of volcanism in Tibesti is unclear; both a hotspot-related mechanism and tectonic effects of the collision between the African Plate and the Eurasian Plate have been proposed. Toussidé is a symmetrical high stratovolcano, the second highest peak in Tibesti and the highest peak in the western Tibesti mountains. In the past it was"
"is connected to Emi Koussi by a narrow ridge. Tectonic activity appears to have occurred in the Tibesti already between the Carboniferous and the Cretaceous, that is between 358.9 ± 0.4 and 66 million years ago. During the earliest stage of volcanism on Tibesti, alkali basalts formed large plateaus. Later, the central volcanoes developed on top of these plateaus. Volcanism in Tibesti has been explained with a mantle plume, as has been proposed for other African volcanoes, although recently tectonic effects of the collision between Africa and Europe and their effects at a distance have also been advanced as an"
"Tarso Emi Chi Tarso Emi Chi (tarso: ""gentle mountain, high plateau""; emi: ""large mountain""; named by the Toubou) is a volcano in Chad. Tarso Emi Chi is part of the Tibesti Mountains, a group of volcanic mountains that cover a surface area of and reach an elevation of . The mountains consist of both a Precambrian crystalline rocks and volcanic rocks. The volcano consists of a lava plateau 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"
"Tarso Yega Tarso Yega (""well"", tedaga) is a stratovolcano in Tibesti, with a summit caldera that is wide and deep. The summit of the volcano reaches a height of , and its caldera is the largest caldera of the Tibesti. Neighbouring volcanoes include Doudriki east, Ehi Dosoatou south and Ehi Fodoboro southwest of the caldera. The Enneri Yega river drains the caldera westward and then south, before joining the Enneri Debarsar; in the past (Holocene) the rivers reached Lake Chad. The history of the volcano is characterized by the emission of tephras, with the downsagging of the caldera floor generating"
"explanation. The oldest rocks below the Tibesti are Precambrian diorites, granites and schists, which are probably of Neoproterozoic age and are differentiated into two units. The volcanic rocks rest on an uplifted basement formed by Cretaceous and Paleozoic sandstone. The latter crop out at the southwestern foot of Emi Koussi, while volcanic rocks dominate north of the volcano, and the Tibesti massif is prevalent east and southeast of Emi Koussi. Older volcanic rocks are exposed in valleys. Emi Koussi has erupted phonolite, trachyandesite and trachyte, as well as mafic rocks like basanite and tephrite. The erupted rocks define two alkaline"
"Monte Arcibessi Monte Arcibessi is a mountain located in the Sicilian province of Ragusa and is one of the highest peaks in the Hyblaen Mountain chain. It stretches between the Chiaramonte Gulfi and Ragusa communes. With its adjacent mountains, Monte Arcibessi is a part of the Miocene volcanic submarine complex, but they are no longer active. There are fortified settlements (""castellieri"") of the Bronze age and Iron Age in the area of Monte Arcibessi. Prehistoric inhabitants, remnants of Archaic Greek settlements, signs from the Hellenistic and Roman periods and Byzantine and Medieval remains. As one of the highest in the"
"Emi Koussi Emi Koussi (also known as Emi Koussou) is a high pyroclastic shield volcano that lies at the southeast end of the Tibesti Mountains in the central Sahara, in the northern Borkou Region of northern Chad. The highest mountain of the Sahara, the volcano is one of several in the Tibesti range, and reaches an elevation of , rising above the surrounding sandstone plains. The volcano is wide and has a volume of . Two nested calderas cap the volcano, the outer one being about in size. Within it on the southeast side is a smaller caldera known as"
"Tsiv-Gombori Range The Tsiv-Gombori () or Gombori (გომბორი) is a mountain range in the Georgian section of Greater Caucasus mountains. It is located in the province of Kakheti, eastern Georgia, and stretches to the distance of 107 km, with the highest mountain being at 1.991 m above sea level. The Gombori range serves as a watershed, separating the Alazani and Iori river valleys, thereby dividing Kakheti into two traditional regions: inner (Shida) and outer (Gare). The slopes of the range are traversed by several smaller river gorges. The Alazani passes through the mountain range affecting the overall climatic conditions in"
"Javakheti Range Javakheti Range (also Kechut Range or Wet Mountains; ) – is a volcanic range in southern Georgia and northern Armenia. The range is about 50 km (31 mi) long and runs north to south from Trialeti to Bazum Range. The highest peak is Achkasar at an elevation 3196 m (10485 ft) above sea level. Other notable peaks include Leyli (3154), Yemlikli (3054), Garanlig (3039), Aghrigar (2973) and Shambiani (2923). Javakheti Range is known with a lot of rainfall too. The name of Wet Mountains originated herein. Range are mainly covered with alpine meadows and grasslands. There are a"
"""Artemisia tilhoana"" and ""Ephedra tilhoana"". Finally, at the highest elevation elevations of the Tibesti, tree heath (""Erica arborea"") grows from moist crevices formed by early lava flows, and 24 different species of moss provide substrate for the tree heath. The large mammals present in the ecoregion are the addax (""Addax nasomaculatus""), Barbary sheep (""Ammotragus lervia""), dorcas gazelle (""Gazella dorcas""), and rhim gazelle (""Gazella leptoceros""). However, rodents are the most represented order of mammals in the Tibesti, and include the Agag gerbil (""Gerbillus agag""), Balochistan gerbil (""Gerbillus nanus""), Cairo spiny mouse (""Acomys cahirinus""), lesser Egyptian jerboa (""Jaculus jaculus""), Libyan jird (""Meriones"
"Trialeti Range Trialeti Range () is an east-west mountain range of the Lesser Caucasus Mountains in the central part of Georgia. The eastern edge of the Range runs along the western border of Tbilisi, while the western edge lies along River Mtkvari to the southwest of Borjomi. The length of the Trialeti Range is 144 kilometers and the maximum width is 30 kilometers. The mountain range was built up by volcanic activity during the Paleogene Era. Young, andesite lava flows are common in the western part of the Range. The highest point is Mount Shaviklde (meaning ""Black Cliff"" in Georgian)"
"Monte Soratte Monte Soratte (ancient: ""Soracte"") is a mountain ridge in the province of Rome, Italy. It is a narrow, isolated limestone ridge with a length of and six peaks. Located some south east of Civita Castellana and c. north of Rome, it is the sole notable ridge in the Tiber Valley. The nearest settlement is the village of Sant'Oreste. Saint Orestes or Edistus, after whom the settlement is named, is said to have been martyred near Monte Soratte. The highest summit is above sea-level. The ridge is part of a Natural Reserve housing a variety of vegetation and fauna."
"Brenta group The Brenta Group or Brenta Dolomites () is a mountain range, and a subrange of the Rhaetian Alps in the Southern Limestone Alps mountain group. They are located in the Province of Trentino, in northeastern Italy. It is the only dolomitic group west of river Adige. Therefore, geographically, they have not always been considered a part of the Dolomites mountain ranges. Geologically, however, they definitely are - and therefore sometimes called the ""Western Dolomites"". As part of the Dolomites, the Brenta Group has been officially recognized as UNESCO World Heritage Site under the World Heritage Convention. Geologically, the"
"to the bunkers in Monte Soratte. Monte Soratte Monte Soratte (ancient: ""Soracte"") is a mountain ridge in the province of Rome, Italy. It is a narrow, isolated limestone ridge with a length of and six peaks. Located some south east of Civita Castellana and c. north of Rome, it is the sole notable ridge in the Tiber Valley. The nearest settlement is the village of Sant'Oreste. Saint Orestes or Edistus, after whom the settlement is named, is said to have been martyred near Monte Soratte. The highest summit is above sea-level. The ridge is part of a Natural Reserve housing"
"Major lava flows have formed vast plateaus that overlie Paleozoic sandstone. The volcanic activity was the result of a continental hotspot that arose during the Oligocene and continued in some places until the Holocene, creating fumaroles, hot springs, mud pools and deposits of natron and sulfur. Erosion has shaped volcanic spires and carved an extensive network of canyons through which run rivers subject to highly irregular flows that are rapidly lost to the desert sands. Tibesti, which means ""place where the mountain people live,"" is the domain of the Toubou people. The Toubou live mainly along the wadis, on rare"
"deep. On the northwest side of Tarso Voon is the Soborom geothermal field, which contains mud pools and fumaroles that vent sulfuric acid. Sulfur and iron have stained the soil bright colors. Fumaroles are also present at the Yi Yerra hot springs on Emi Koussi. Tarso Tôh was an active volcano in the early Holocene. The volcanic area of the Tibesti Mountains is located entirely in Chad; it covers about a third of the total area of the Tibesti Mountains and is responsible for between of rock. The rest of the Tibesti Mountains consists of volcanic plateaus (""tarsos"" in the"
"seen from orbit. Supposedly the entire Tibesti can be seen from the northern summits. It is a shield volcano with a diameter of and an estimated volume of . The summit of Emi Koussi is formed by two overlapping calderas, which together form a wide elliptical caldera that extends from northwest to southeast. The northern caldera formed first, then the southern caldera which is about deeper below the northern one. high scarps form the inner margin of the southern caldera, with the floor at an elevation of . Before the formation of the calderas, the volcano may have reached a"
"number of small-sized lakes in and around the Javakheti Range. Javakheti Range Javakheti Range (also Kechut Range or Wet Mountains; ) – is a volcanic range in southern Georgia and northern Armenia. The range is about 50 km (31 mi) long and runs north to south from Trialeti to Bazum Range. The highest peak is Achkasar at an elevation 3196 m (10485 ft) above sea level. Other notable peaks include Leyli (3154), Yemlikli (3054), Garanlig (3039), Aghrigar (2973) and Shambiani (2923). Javakheti Range is known with a lot of rainfall too. The name of Wet Mountains originated herein. Range are"
"endemism levels are much higher in the Tibesti than in the Aïr Mountains or the Ennedi Plateau, although the vegetation's coverage is highly dependent on rainfall. A number of oases lie along the courses of the ""enneris"" such as Enneri Yebige, which is virtually unexplored. These oases, which are more numerous to the north and west of the range, have vegetation of the genera ""Acacia"", ""Ficus"" (fig trees), ""Hyphaene"" and ""Tamarix"". Most gueltas are lined with macrophytes including ""Cyperus laevigatus"", ""Equisetum ramosissimum"", ""Juncus fontanesii"" and ""Scirpus holoschoenus"". ""Acacia nilotica"" grow near these water basins. ""Myrtus nivellei"" and ""Nerium oleander"" grow"
"are very steep, north are steep and step-like and drainages to the west are gentler but have still developed deep canyons. Presently, acacias grow up to elevations of . Tarso Emi Chi Tarso Emi Chi (tarso: ""gentle mountain, high plateau""; emi: ""large mountain""; named by the Toubou) is a volcano in Chad. Tarso Emi Chi is part of the Tibesti Mountains, a group of volcanic mountains that cover a surface area of and reach an elevation of . The mountains consist of both a Precambrian crystalline rocks and volcanic rocks. The volcano consists of a lava plateau that originated in"
"a depression. Basaltic vents and Lava domes were emplaced within this caldera, and an intrusion named Ehi Yodéï developed farther south. The caldera is heavily eroded, with almost the entire southern side eroded away, and the younger Voon ignimbrite has been emplaced inside of it; it belongs to a different volcano, Tarso Voon. Humans have used the caldera for irrigated agriculture. Tarso Yega Tarso Yega (""well"", tedaga) is a stratovolcano in Tibesti, with a summit caldera that is wide and deep. The summit of the volcano reaches a height of , and its caldera is the largest caldera of the"
"Julian Alps The Julian Alps (, , ) are a mountain range of the Southern Limestone Alps that stretch from northeastern Italy to Slovenia, where they rise to 2,864 m at Mount Triglav, the highest peak in Slovenia and of the former Yugoslavia. They are named after Julius Caesar, who founded the municipium of Cividale del Friuli at the foot of the mountains. A large part of the Julian Alps is included in Triglav National Park. The second highest peak of the range, the 2,775 m high Jôf di Montasio, lies in Italy. The Julian Alps cover an estimated 4,400"
"enter the Tibesti range, but were killed by a Toubou warrior. While Nachtigal provided an accurate description of the population, his account discouraged any new adventure into the Tibesti for over 40 years, as he was convicted by the Toubou of spying for Bismarck and only released after the intervention of Maï Arami Tetimi. Later expeditions carried out between 1920 and 1970 yielded valuable information on the geology and petrology of the range. The French anthropologist Charles le Cœur and his wife Margaret, a geographer, lived among the Teda of Tibesti between 1933 and 1935. Le Cœur was the first"
"and ""Selaginella"" species grow at fumaroles. The wood rush ""Luzula tibestica"" is endemic on Emi Koussi. The fern ""Asplenium quezelii"" was discovered on Emi Koussi and at first thought to be endemic there before it was found to be identical to ""Asplenium daghestanicum"", a species also previously considered to be endemic to Dagestan, more than away from Emi Koussi. Emi Koussi Emi Koussi (also known as Emi Koussou) is a high pyroclastic shield volcano that lies at the southeast end of the Tibesti Mountains in the central Sahara, in the northern Borkou Region of northern Chad. The highest mountain of"
"Chita. Yablonoi Mountains The Yablonoi Mountains or Yablonovy Mountains (Яблоновый хребет in Russian) is a mountain range in Siberia. It is in Transbaikal (mainly in Chita Oblast) in Russia. The range runs north-east from Mongolia, passing just to the east of Lake Baikal. The Yablonoi Mountains run for about 1600 kilometres before joining with the Stanovoi Range. The range forms the dividing line between the rivers that empty into the Arctic Ocean and those that empty into the Pacific. The range is not particularly tall or large, being long and thin. The tallest peaks are 'Bolshoy Sokhondo' at 2505м and"
"unity never been seen before in Chad. After a series of defeats in northeastern Chad, Libyan forces withdrew fully from the Tibesti in March 1987. Although the Tibesti has since entered an era of relative peace, the years of conflict have left the area strewn with thousands of landmines. Due to its isolation and geopolitical situation, the Tibesti Mountains were long unexplored by scientists. The German Gustav Nachtigal, dispatched by Otto von Bismarck, was the first European to explore, albeit with great difficulty, the Tibesti in 1869. Prior to Nachtigal's expedition, an American along with two missionaries had attempted to"