North Africa has three main geographic features: the Sahara desert in the south, the Atlas Mountains in the west, and the Nile River and delta in the east. The Atlas Mountains extend across much of northern Algeria, Morocco, and Tunisia. These mountains are part of the fold mountain system that also runs through much of Southern Europe. They recede to the south and east, becoming a steppe landscape before meeting the Sahara desert, which covers more than 75 percent of the region. The tallest peaks are in the High Atlas range in south-central Morocco, which has many snowcapped peaks.
South of the Atlas Mountains is the dry and barren expanse of the Sahara desert, which is the largest sand desert in the world. In places the desert is cut by irregular watercourses called wadis—streams that flow only after rainfalls but are usually dry. The Sahara’s major landforms include ergs, large seas of sand that sometimes form into huge dunes; the hammada, a level rocky plateau without soil or sand; and the reg, a level plain of gravel or small stones. The Sahara covers the southern part of Algeria, Morocco and Tunisia, and most of Libya. Only two regions of Libya are outside the desert: Tripolitania in the northwest and Cyrenaica in the northeast. Most of Egypt is also desert, with the exception of the Nile River and the irrigated land along its banks. The Nile Valley forms a narrow fertile thread that runs along the length of the country.
Sheltered valleys in the Atlas Mountains, the Nile Valley and Delta, and the Mediterranean coast are the main sources of fertile farming land. A wide variety of valuable crops including cereals, rice and cotton, and woods such as cedar and cork, are grown. Typical Mediterranean crops, such as olives, figs, dates and citrus fruits, also thrive in these areas. The Nile Valley is particularly fertile, and most of the population in Egypt live close to the river. Elsewhere, irrigation is essential to improve crop yields on the desert margins.