North Africa and Levante: The Region

Africa is a very large continent, only superseded by Asia. Apart from the Atlas Mountains in the northwest, the region covered in this volume consists mostly of crystalline base rock, widely covered by aeolian sands in the Saharan region. The crystalline rocks are exposed, e.g., in the Air and Ahaggar massifs. The Red Sea Hills of Egypt are formed by granites, gneisses, and schists. This chapter deals especially with the Maghreb part of the Mediterranean Region, comprising folded mountains, e.g., at the northwestern extremity of the continent, dominated by the Atlas Mountains, originating through Tertiary folding and sediment uplift extending more than 3000 km from Morocco to Tunisia, and reaching up to 4165 m (Mount Toubkal). The coastal Rif Atlas represents the oldest part of the range. Prevalent rocks in the region are sediments, in particular limestones, and some fairly small areas of exposed Precambrian basement, and some volcanic outcrops. Most of the area is however covered by parts of the Saharan desert from the Atlantic coast to the Red Sea, characterized by high temperatures and mostly a dry atmosphere, consisting largely of aeolian sand deposits. Most of the Sahara consists of Cretaceous and Tertiary deposits, with some crystalline rock exposed in higher mountains, e.g., Tibesti, Ahaggar, or Jebel Uweinat, with some small, interspersed inselbergs formed by granite. The depressions are filled with gravel (Reg) and sand (Erg) deposits Pleistocene deposits, which form either sand deserts (erg) or gravel deserts (reg), and interspersed terrace landscape like stone desert (Hamada) and dry valleys (Wadis).