Emi Koussi Volcano, Chad
Emi Koussi is an extinct high shield volcano that lies at the south end of the Tibesti Mountains in the central Sahara of northern Chad.
It is the highest mountain in Chad, and also the highest in the Sahara. The volcano is one of several in the Tibesti massif, and reaches 3445 m (11302 ft) in altitude, rising 2.3 km (1.43 mi) above the surrounding sandstone plains. The volcano is 60 by 80 km (37 to 50mi) wide.
Upon more detailed examination, the rim of the volcano appears to consist of two rings. This is because two nested calderas cap the volcano, the outer one being about 12 by 15 km in size. Within it on the southeast side is a smaller caldera, about 2-3 km wide and 350 m deep.
Numerous lava domes, cinder cones, maars, and lava flows are found both within the calderas and along the outer flanks of the shield.