Physical Geography
The principal physical features of Algeria are the Atlas Mountains in the north and the Sahara, to the south, a vast desert that covers about nine-tenths of the country.
The Atlas Mountains are a faulted system, with steep-sided mountains and deep ravines in the more rugged parts. The region consists of three roughly parallel northeast-southwest zones. Beginning near the coast, they are (from north to south) the Tell Atlas, the High Plateaus, and the Saharan Atlas. The highest ranges of the Tell Atlas rise more than 7,500 feet (2,290 m) above sea level. The rough terrain is interrupted by small plains, particularly along the coast.
The High Plateaus are marked by rolling hills, some steep cliffs, and flat plains, with an average elevation of 3,000 feet (910 m). Though generally low, the Saharan Atlas, which fringes the desert, rises to a height of more than 7,600 feet (2,320 m).
The Sahara is made up mainly of low tablelands, with occasional areas of high terrain, such as the Ahaggar massif in the south. Here rises 9,573-foot (2,918-m) Tahat, the highest point in Algeria. Part of the Sahara consists of sand and dune areas, called ergs, among the largest of which are the Great Eastern Erg and the Great Western Erg. There are also areas of exposed bedrock, called hammadas.
There are few rivers and lakes. The Chelif River, 450 miles (720 km) long, is the chief river. Of the rivers that originate in the Saharan Atlas, it is the only one to reach the Mediterranean. Many watercourses are dry except after winter rains. On the High Plateaus and in the Sahara are expansive salt flats and marshes, known as chotts or shotts. Many of them are covered by shallow water during winter. Chott Melrhir, in the Sahara near the Saharan Atlas, occupies a depression below sea level.
Coastal Algeria has a Mediterranean type of climate, with mild, rainy winters and hot, dry summers—a climate similar to that of southern California. January temperatures average about 50° F. (10° C.); July temperatures, just below 80° F. (27° C.). Most of the area has 30 inches (760 mm) or more of rainfall a year; some places receive more than 50 inches (1,270 mm).
On the High Plateaus, there is a dry steppe climate, with cooler winters and slightly hotter summers. Rainfall averages 10 to 20 inches (250 to 500 mm) annually, all of it coming in winter and spring. The Atlas Mountains have a varied climate because of their elevation.
The Sahara is one of the world's most desolate areas. Summer temperatures average above 95° F. (35° C.) and frequently rise as high as 110° F. (43° C.). Temperature changes between night and day are extreme. There is little or no rain.
In the more humid mountain areas, and occasionally along the coast, are oaks (particularly cork oaks) and coniferous trees, mainly pines, cedars, and cypresses. However, much of northern Algeria is covered with scrubby bush-type vegetation, called maquis. On the High Plateaus are dry grasslands. Beyond the mountain vegetation of the Saharan Atlas begins the true desert, where vegetation is nonexistent or sparse.
