The plateaus have borders clearly marked by important mountain groups. At the S. they reach the Saharan Atlas, which they understand under the climatic and anthropic point of view. To the N. and to the NE. they lead to a great chain, which crosses Algeria obliquely, from Tlemcen to Biscra. This chain has a deep orographic unity, forming the mountainous crown at the limit of the ancient penepian (the Algerian Horst), which constitutes the base of the plateaus (see atlas). Therefore this crowning is composed of disparate elements: the Aurès, the Bellesma, the Bou Thaleb, the Maadid, the Dira, the Djebel Lakhdar, the Ouarsenis, the Tiaret mountains, the causses of Saïda and Tlemcen. There is not yet a universally accepted collective noun; and this is absurd, since there is no type of structure in the whole of Algeria that has the same human importance. So it was proposed to adopt one; it could be called the chain of the limes, following it, more or less, the limes of the Roman empire, the layout of which has been reconstructed with great precision.
To the west, the Algerian highlands continue the same in eastern Morocco, up to the middle Muluia valley and the first slopes of the Middle Atlas. This is a point where history has somehow taken over geography. For Algeria geography, please check franciscogardening.com.
Within these well-defined boundaries, the base of the plateaus is slowly and progressively rising from the E. to the O., from the Hodna basin (from 4 to 500 m.) to the border of Morocco (from 1000 to 1200 m.); beyond the border, the base rises up to 1400 m. At the lowest point, the Hodna basin, the continuity of the Saharan Atlas undergoes major interruptions between the Biban chain and the Aurès. The Hodna and the Sahara are in communication on the same level; that is the door of Biscra, the road of the invasions, a point of great historical importance.
Enclosed in their circle of mountains, the plateaus, through the geological ages, have always suffered from drought, and the mountain range, as a whole, has not been much affected by erosion. From the hydrographic point of view, the elevated plateaus are a series of closed basins, at the bottom of each of which there is a salt lake: the Hodna, which is the largest of all, the Zahrez, the Chergui and Gharbi lakes. However at one point within the borders of Algeria, the regressive erosion of a Mediterranean wadi has captured a highland wadi, resulting in the Chéliff, which is one of the longest and most important rivers in the country. The other uidians (plur. Of ued, wadi) of the plateaus are short streams, which descend from the mountain to the nearest salt lake; the exception is the ued Djedi, which was born at S. di Dielfa, passes through Laghouat and ends up near Biscra, in the large closed basin of the lakes of Constantina and Tunis (Chott Melghir). Its valley, with good pastures, is remarkable for its length and direction. Skirting the southern base of the Saharan Atlas, it has historically been almost a border ditch between the high plateaus and the Sahara, and constitutes a communication route traveled by nomads, between Laghouat and Biscra.
The uidian of the highlands are steppe rivers, mostly dry, which, after a hurricane, convey huge amounts of water, pebbles and silt laden, and that, when they arrived in their expansion zone, follow a capricious course, precluding themselves from walking with the mass of accumulated floods. They have operated in this way through the geological ages, and have encrusted the entire surface of the high plateaus with their filling, thus creating a plain landscape, where the horizon line is often almost as regular as that of the sea.
On the highlands, as indeed in the Saharan Atlas, the annual average rainfall is generally less than 300 mm.; too low for agriculture to be made possible, except for certain privileged points of the northern extremity, such as the region of Tiaret and the Sersou, object of millennial military and economic struggles between nomads and sedentaries,
In the parts of the Saharan Atlas which are higher and better favored by the nature of the soil, namely in Oulad Naïl (Djelfa), in Diebel Amour (Aflou), some tracts of forests have been preserved: green oaks, but mainly the more resistant species to drought, juniperus, tuia. But, taken together, the high plateaus are an unbroken steppe of alpha and mugwort.
However disadvantageous these conditions may appear to us, we must not forget that they are much better than those of the Sahara. At the S. of the Saharan Atlas the precipitations immediately drop below 100 mm., And the vegetation disappears in every part, except in certain privileged points, which are very rare.
At heights that are just a little farther away from a thousand meters there are considerable fluctuations in temperature, in an extremely dry air: hot summers, but cold winters with frequent snowfalls. Exceptionally, once or twice there has been the case of a small group of soldiers surprised and destroyed by a violent snowstorm. Such climatic conditions require in Africa the white Mediterranean man, and train him to tolerance and energy. The highlands seem destined to feed great nomadic tribes, “these beautiful wild beasts” as Ibn Khaldūn puts it.
In the remotest historical antiquity, which we glimpse only through funerary monuments, the elevated plateaus already appear clearly distinct from the rest. They are covered with graves in poor condition, modest heaps of stones, which always appear isolated or in very small groups. At N. of the border chain the tombs are much more accurate, often quite different (dolmens) and always grouped in cemeteries, which sometimes have a great extension. The Saharan Atlas is the only region of Algeria where there are rock inscriptions. The few savages who rest under the piles of stones (even if they are not the same ones who engraved the stones with inscriptions), were most likely the Getuli, of whom the Roman Empire did not give any thought, being they outside the border, despite some belated ambitions to carry the border further forward.
It must be borne in mind that the population was distributed very differently from today. The highlands were almost uninhabited, as evidenced by the presence of herds of wild elephants, thanks to which Carthage could supply its armies. The Getuli were of no importance, as they did not have a camel. The Berbers were unable to cross the immense desert areas, and the whole Algerian Sahara at S. Oued Djedi was Ethiopian dominion, that is to say Negro. The introduction of camel breeding, starting with Septimius Severus, was one of the benefits brought by the Roman administration, but it was a fatal benefit to the benefactor, since little by little the great tribes of nomadic camel drivers were formed, who invaded the Sahara, and nowhere did they become as prosperous as on the Algerian highlands. The first to take advantage of the camel were the Berbers, whom Arab historians call with the name of Zenātah; these, from the century. XI onwards, they were strengthened by the invasion of the Arab Hilalian Bedouins, whose language they adopted belatedly (not before the XIV century), eventually merging entirely with them.
The Algerian evolution is to be attributed to those great tribes of nomadic camel drivers, who now speak Arabic and are the only residents of the highlands; since they precisely prevented the rise not only of a nation, but even a state of some duration, as they were constituted, whatever their value, in Tunisia and Morocco; they have prevented the formation of large indigenous cities, such as Fez and Tunis; and they have reduced the country to a state of decomposition, which has attracted the foreign conquerors, first the Turks, then the French.
The harmful power of these nomads has not ceased, although after the annihilation of Abd el-Kader, who was sultan of the highlands, that is, after 1848, the military prestige of France was fully established; but in this long period of peaceful domination, economic development has not progressed as expected and as it has in other parts of Algeria. Yet all that was needed has been done: there are railways from Oran to Colomb-Béchar and Méchéria, from Algiers to Djelfa, from Constantina to Biscra and Tuggurt; the automobile services operate, extending and completing the railway network. On the northern border, where the climate has allowed it, European colonization has lavished its attention on the land (Tiaret, il Sersou); but the steppe as a whole can only be the land of the sheep. L’ the administration organized water supplies, drilled wells, studied crossbreeding and shearing: the results did not match its efforts. Here, as elsewhere, great progress will only be possible through European private initiative; interesting attempts made to this end were unsuccessful. In Algeria, where the settlers have grown so many that they have almost reached one million, there is still not a single squatter. All farming is always in the hands of indigenous nomads, and is done with primitive methods. In all this we must recognize a setback, which can be considered temporary, especially in the face of the needs of national wool, determined by the new physiognomy of the world market following the war.