North Africa stretches from the Atlantic coast of the Maghreb to the Red Sea borders of Egypt and Sudan. The region’s geography is defined by the meeting of the Mediterranean Sea, a continental desert, and significant mountain ranges. Key landforms include the world’s largest hot desert, a long coastal mountain system, and the planet’s longest river system. This combination of features has dictated historical human settlement patterns, concentrating life along the coastlines and river banks.
The Sahara Desert and Its Interior Plateaus
The Sahara Desert covers over 9.2 million square kilometers of North Africa. Contrary to the common image of endless sand, the desert is a mosaic of landforms shaped by aeolian (wind) processes. The classic mobile sand dunes, known as ergs, constitute only a fraction of the total desert area.
The Sahara’s surface is predominantly made up of two other landforms. Extensive plains of wind-scoured gravel and pebbles, often referred to as desert pavement, are known as regs. In contrast, large, elevated surfaces of exposed, weathered bedrock form rocky plateaus called hammadas.
Within this arid expanse, ancient geological structures rise as isolated massifs, forming interior plateaus. The Ahaggar (Hoggar) Mountains in southern Algeria and the Tibesti Mountains near the border of Libya and Chad represent elevated volcanic and crystalline rock formations. These massifs act as sources for ancient, now-dry river systems that once transported sediments into the surrounding desert basins.
The Atlas Mountain Range System
The Atlas Mountains form an orographic barrier along the northwestern edge of North Africa, running through Morocco, Algeria, and Tunisia. This system is a series of folded mountains created by the collision of the African and Eurasian tectonic plates. The High Atlas, located in Morocco, contains the range’s highest peaks, which remain snow-capped into the summer months.
The mountain system creates a rain shadow effect. Moist winds from the Atlantic Ocean and the Mediterranean Sea are forced upward, causing precipitation on the northern (windward) slopes. As the dry air descends the southern (leeward) side, it heats up and absorbs moisture, severely limiting rainfall and contributing to the aridity of the adjacent Sahara. This climatic barrier separates the Mediterranean’s fertile coastal strips from the desert interior.
The Nile River Valley and Delta
The Nile River system defines the geography of eastern North Africa, flowing through the arid environment of Egypt and Sudan as an exotic river. The Nile Valley is a narrow, geological trench carved into the desert landscape, where the river’s historical flooding deposited rich alluvial soils. This concentration of fertile land creates a habitable ribbon surrounded by non-arable desert.
As the river nears the Mediterranean Sea, it forms the Nile Delta, one of the world’s largest deltaic landforms. The Delta is a low-lying, fan-shaped accumulation of sediment, where the river splits into numerous distributaries. This landform was created by the continuous deposition of silt, clay, and sand, which historically built up the agricultural floodplains of Lower Egypt. The Delta’s geological structure is a direct result of thousands of years of fluvial action and sedimentary processes.