Knowra Tassili n'Ajjer Tassili n'Ajjer A sandstone plateau and mountain range in southeastern Algeria, known for prehistoric rock art, eroded stone formations, and distinctive Saharan ecosystems.
Tassili n'Ajjer rock art : Prehistoric paintings and engravings found across the Tassili n'Ajjer plateau. These images make the plateau one of the world's richest concentrations of prehistoric rock art.
Sandstone : A sedimentary rock formed when sand grains are compacted and cemented together. The plateau's resistant sandstone layers produce its cliffs, pillars, and rock shelters.
Saharan rock art : Prehistoric paintings and engravings found on rock surfaces across the Sahara. Tassili's art belongs to a much wider record of Saharan imagery.
Sahara : The world's largest hot desert, extending across northern Africa. Tassili is a mountainous enclave within the Sahara's vast arid landscape.
Sefar : A sandstone settlement and archaeological site in Tassili n'Ajjer, Algeria. Its rock shelters contain extensive paintings and engravings.
Differential erosion : The uneven wearing away of rock layers with different resistance to weathering. It sculpts Tassili's contrasting cliffs, towers, and narrow passages.
African Humid Period : A period when much of northern Africa was substantially wetter than today, especially between about 14,500 and 5,000 years ago. Its lakes and grasslands help explain the animals and pastoral scenes depicted in Tassili.
Ahaggar Mountains : A volcanic mountain massif in southern Algeria, west of Tassili n'Ajjer. This neighboring highland shares the region's isolated Saharan ecosystems.
Round Head period : An early phase of Saharan rock art, named for its distinctive human figures with rounded heads. The plateau's early paintings include characteristic Round Head figures.
Physical weathering : The breakdown of rock into smaller pieces without changing its chemical composition. Temperature changes and other physical forces help fracture exposed sandstone.
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