The Aïr Mountains in the Sahara Desert, Niger18.2N 7.9E
The Aïr Mountains (also known as the Aïr Massif) is a triangular massif in northern Niger, in the Sahara desert. These mountains reach elevations of over 6,000 ft (1 830 m) and extend over an area 84 000 km².
Geologically, the Aïr Mountains consist of peralkaline granite intrusions which appear dark in colour (unusual since most granitic masses are light-toned in the field). In the Sahara Desert such mountains often stand out in stark relief as topographic heights amidst lowlands covered by sand.
The terrain consists of high plateau, mountain ranges, and broad, sandy valleys and seasonal wadis which once contained rivers. Areas of these deep, often intersecting, valleys also contain waterborne clay and silt deposits. Underground watercourses in some of these valleys continue to provide year round oasis and seasonal vegetation.
The Aïr mountains themselves consist of nine almost circular massifs rising from a rocky plateau, bordered by the sand dunes and plain of the Ténéré Desert to the east.
The massif is an eroded Cambrian metamorphic plateau, punctuated by a series of flat-topped, granite intrusion peaks, which include Mont Idoukal-n-Taghès (Niger’s highest point at 2022 m), Mont Tamgak (1988 m), Mont Greboun (1944 m), Adrar Bous, Fadei, Chirriet, Taghmert, Agueraguer, Takaloukouzet, and Goundai. Volcanic features include the extinct caldera of Arakao and one of the largest ring dike systems in the world. At Izouzaoenehe, lie the marble Blue Mountains, and the lower Zagado valley is surrounded by white marble hills.