GEOGRAPHICAL CHARACTERISTICS OF ALGERIA. 3 



Atlas and Atlas of the Tell or the Tellian Atlas, names which are self- 

 explanatory. The Tellian Atlas and all territory between this range and 

 the Mediterranean Sea is known as the Tell, or the land of hills. This is 

 the most important part of Algeria from an agricultural standpoint, and 

 furnishes grain and other products. Here also are the most important 

 forests, oak, pine, and- cedar. Between the two ranges of the Atlas lies 

 the region of the steppes or plateaus, in this study referred to as the 

 High Plateau, inasmuch as the average altitude is over 3,000 feet. The 

 steppe region is highest in the west and is wedge-shaped, in conformity 

 to the bounding mountains. In the eastern portion it breaks up into 

 mountain valleys. The topography of the High Plateau is monotonous. 

 The surface is gently rolling, and here and there are undrained depres- 

 sions, or chotts, where salts accumulate. In rainy seasons the chotts 

 contain water, but in the arid summers they are dry. The region of the 

 steppes is of no agricultural value, although, as will appear below, the 

 harvesting of the aifa grass, which occupies vast areas, is of considerable 

 importance. 



South of the Saharan Atlas lies the desert, comprising about 2,000,000 

 square miles, the topography of which is extremely varied. For present 

 purposes it is sufficient to say that in the extreme southern portion of 

 the Algerian Sahara, and crossed by the Tropic, there is an extensive 

 highland, the plateau of Idghagh, where an elevation exceeding 5,000 feet 

 is reached. All of the Sahara to the west of this plateau, or to the west 

 of a line drawn north from it, appears to be above sea-level (much of it 

 having an altitude of 1,000 feet), and of greater geological age than that 

 portion of the desert lying to the east. North from the plateau of Idghagh 

 the country gradually descends to the depression of which the great Chott 

 Melghir is a part, a region below the level of the sea. Here extends also 

 one of the longest oueds of the Sahara, the Oued Igharghar, which takes 

 its rise in the plateau of Idghagh and empties in the Chott Melghir, an 

 entire length exceeding 700 miles. In the western part of the Sahara the 

 surface descends to the Atlantic, but in the eastern part it falls away to 

 the Mediterranean. 



Turning now to consider the part of southern Algeria with which this 

 study especially deals — lying between Laghouat and Ghardaia, between 

 Ghardaia and Ouargla, and between the latter place and Biskra, all to the 

 south of the Saharan Atlas — we find topographical details which are prob- 

 ably representative of much of the rest of the Great Desert. Laghouat 

 has an elevation of 2,400 feet. It lies on the northern edge of the region 

 of the dayas. This region is characterized by the poor development of 

 its drainage and has a slightly undulating surface with frequent depres- 

 sions, each the center of an area of rather small extent, from which it 

 receives flood-waters. The dayas differ from the other undrained areas, 

 the chotts, in that they do not contain an excess of salt, owing probably 



