TOPOGRAPHY. 15 



and the Santa Lucia ^Mountains district of the western part of Monterej^ 

 Count}', in California. 



Numerous streams arise in the mountains of the coast region, trav- 

 erse the Tell, and empt}" into the sea. Most of these are torrents, 

 discharging large volumes of water in winter, but in summer dwin- 

 dling to mere rivulets. Not infrequent!}' no water is to be seen in the 

 channel, but in that case it is generally to be found under the bed of 

 the stream. Owing to their relatively great fall, and the denuded 

 condition of much of the soil, the amoimt of erosion accomplished by 

 Algerian water courses is disproportionately large. These character- 

 istics are especially marked in western Algeria. In the eastern part 

 of the colony, where the rainfall is better distributed and more of the 

 surface of the country is forested, the How of the streams is more 

 regular. The small importance of Algerian water courses is doubtless 

 to be accounted for by the fact that most of the precipitation occurs 

 on or near the coast, while the interior of the country is extremely 

 arid. 



Only one I'iver of the Tell region also traverses the high plateau 

 region. That is the Cheliff, the most important water course in Alge- 

 ria, which rises in the mountains that border the Sahara on the north. 

 It has a total length of about 330 miles, draining an area of about 

 7,500,000 acres. Its flow in summer is only 100 to 175 cubic feet per 

 second, although in winter from 500 to 2,000 cubic feet are discharged. 

 It is obvious that only a small portion of the valley of the Chelifi' can 

 be irrigated throughout the year. Not even this stream is navigable, 

 except, near its mouth, for small boats. 



HIGH PLATEAU OR STEPPE REGION. 



Between the two chief mountain systems of Algeria extends a vast 

 region of elevated plains, with an average elevation of a little more 

 than 3,000 feet above sea level. The greatest width of the high pla- 

 teau in Oran Department is about 125 miles, whence it diminishes grad- 

 ually toward the east until on the frontier of Tunis a narrow river valley 

 is all that remains. In topography, and to some extent in vegetation, 

 this region greatly resembles parts of Nevada and New Mexico. In 

 its widest part it consists of a gently rolling expanse, sometimes with- 

 out a hill to break the monotonous horizon. In other places isolated 

 mountain groups rise like islands out of the sea. Near its northern 

 and southern borders spurs from the mountain chains that bound it 

 extend into the plain. Toward the east the mountains are higher and 

 approach nearer together. In the Department of Constantine the dis- 

 tinctive character of the high plateau is lost, and it breaks up into a 

 series of valleys a few miles wide, with gently sloping sides, separated 

 by high hills and mountains. The great masses of the Aures and 



