Sandstone arches and rock art in the Sahara
The Ennedi Plateau in north-eastern Chad is a sandstone massif eroded by wind and water into arches, pillars and canyons rising from the Sahara. Among its most famous sights are the Aloba Arch, one of the tallest natural arches in the world, and the Guelta d'Archei, a permanent pool in a gorge where camels come to drink. Rock paintings and engravings show cattle, camels and people from thousands of years ago. The region is extremely remote and is reached only on organised expeditions.