Tibesti mountains

Tibesti
The Tibesti, including Emi Koussi summit, seen from the International Space Station
Highest point
Peak	Emi Koussi
Elevation	3,445 m (11,302 ft)
Coordinates	18°33′6″N 19°47′36″E / 18.55167°N 19.79333°E / 18.55167; 19.79333
Dimensions
Length	380 km (240 mi)
Width	350 km (220 mi)
Area	100,000 km2 (39,000 sq mi)
Geography
Countries	Chad and Libya
Range coordinates	20°47′N 18°03′E / 20.78°N 18.05°E / 20.78; 18.05Coordinates: 20°47′N 18°03′E / 20.78°N 18.05°E / 20.78; 18.05
Geology
Age of rock	Oligocene
Type of rock	Basalt, Dacite, Ignimbrite, Trachyte, Sandstone

The Tibesti Mountains are a mountain range in the central Sahara, primarily located in the extreme north of Chad, with a small extension into southern Libya. The highest peak in the range, Emi Koussi, lies to the south at a height of 3,445 metres (11,302 ft) and is the highest point in both Chad and the Sahara. Bikku Bitti, the highest peak in Libya, is located in the north of the range. The central third of the Tibesti is of volcanic origin and consists of five shield volcanoes topped by large craters: Emi Koussi, Tarso Toon, Tarso Voon, Tarso Yega, and Toussidé. 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 oases where palm trees and limited grains grow. They harness the water that collects in gueltas, the supply of which is highly variable from year-to-year and decade-to-decade. The plateaus are used to graze livestock in the winter and harvest grain in the summer. Temperatures are high, although the altitude ensures that the range is cooler than the surrounding desert. The Toubou, who first appeared in the range in the 5th century BC, adapted to these conditions and turned the range into a large natural fortress. They arrived in several waves, taking refuge in times of conflict and dispersing in times of prosperity, although not without intense internal hostility at times.