in the southwestern parts is the mountain range tassili n'ajjer located. this area is a subject of great archaeological interest and was put up on the "world heritage list" by unesco in 1982. the area is known for extreme aridity and extreme heat, as daytime temperatures are commonly between 46 °c (113 °f) and 51 °c (122 °f) during the hottest period of the year in most of the desert.