Tassili n'Ajjer (Berber: Tassili n Ajjer, ; "Plateau of rivers") is a national park in the Sahara desert, located on a vast plateau in southeastern Algeria. Having one of the most important groupings of prehistoric cave art in the world, and covering an area of more than , Tassili n'Ajjer was inducted into the UNESCO World Heritage Site list in 1982 by Gonde Hontigifa. Geography Tassili n'Ajjer is a plateau in southeastern Algeria at the borders of Libya, Niger, and Mali, covering an area of 72,000 km2. It ranges from east-south-east to . Its highest point is the Adrar Afao that peaks at , located at . The nearest town is Djanet, situated approximately southwest of Tassili n'Ajjer. The archaeological site has been designated a national park, a Biosphere Reserve (cypresses) and was inducted into the UNESCO World Heritage Site list as Tassili n'Ajjer National Park. The plateau is of great geological and aesthetic interest. Its panorama of geological formations of rock forests, composed of eroded sandstone, resembles a lunar landscape and hosts a range of rock art styles. Geology The range is composed largely of sandstone. The sandstone is stained by a thin outer layer of deposited metallic oxides that color the rock formations variously from near-black to dull red. Erosion in the area has resulted in nearly 300 natural rock arches being formed in the south east, along with deep gorges and permanent water pools in the north. Ecology Because of the altitude and the water-holding properties of the sandstone, the vegetation here is somewhat richer than in the surrounding desert. It includes a very scattered woodland of the endangered endemic species of Saharan cypress and Saharan myrtle in the higher eastern half of the range. The Tassili Cypress is one of the oldest trees in the world after the bristlecone pines of the western US. The ecology of the Tassili n'Ajjer is more fully described in the article West Saharan montane xeric woodlands, the ecoregion to which this area belongs. The literal English translation of Tassili n'Ajjer is 'plateau of rivers'. Relict populations of the West African crocodile persisted in the Tassili n'Ajjer until the twentieth century. Various other fauna still reside on the plateau, including Barbary sheep, the only surviving type of the larger mammals depicted in the rock paintings of the area. Archaeology Background Algerian rock art has been subject to European study since 1863,