The Tunisian territory forms the eastern edge of the Maghreb, the Mediterranean “balcony” of the African continent, and generally represents the structural continuation of neighboring Algeria. The morphology is very varied: the northern section is in fact crossed by various mountainous alignments of Cenozoic origin, followed by a central depression zone; Finally, tabular reliefs occupy the southern sector, Saharan, resting on an ancient crystalline base which has remained almost stable since the Mesozoic. The northern reliefs are part of the great Atlas system, which here, however, has now lost the roughness and the high peaks of Morocco and Algeria. Oriented, according to the trend of the entire system, from SW to NE, the Tunisian Atlas is in fact characterized by relatively modest reliefs, often interspersed with plateaus, hilly areas, wide valleys; however, it is possible to distinguish two main series of chains divided by the groove of the Medjerda (or Megerda) river: to the N the Atlas called Telliano (or Tell), to the S the Saharan Atlas (or simply Atlas). Visit healthinclude.com for exotic Tunisia.
The reliefs of the Tell, mainly made up of sandstones, hang directly on the coast, determining its varied outline; they are relatively inaccessible, often interrupted by slopes; particularly vigorous, although it does not even reach 1000 m in height, is the Krumiria massif (Khroumirie), which occupies the north-western end of the country, where it connects to the Algerian mountains of the Medjerda. The inner side of the Tell descends to the vast depression formed by the Medjerda valley, covered by sediments mostly from the Cretaceous (Mesozoic era); then rises the Tunisian section of the Atlas, or Tunisian ridge, a continuation of the Algerian group of the Tébessa; these are even more discontinuous chains than the tellian ones, since the exogenous agents have more easily and deeply eroded the mainly calcareous rocks, sometimes reducing them to tabular reliefs that sudden escarpments (kalaat) delimit. The average altitude of the chain is not high, even though it contains the country’s highest peak, Jebel Chambi (1544 m). A series of mostly tabular offshoots, generally of a few hundred meters while not missing higher peaks (Jebel Orbata, 1164 m), gradually descends into a large depression area, approx. 350 km from W to E, occupied by ancient basins today dried up and covered by saline residues, the chotts, which only exceptionally present, in the rainy season, a surface layer of brackish water. The largest is the Chot Jerid, which is lowered to only 17 m and through which the Sahara could once go as far as the Mediterranean, which here is deep inside the Tunisian territory with the AS of the chotts belt the real Saharan section of Tunisia begins. The desert here shows all its three typical aspects: rocky (hamada), pebbly (serir), sandy (erg); in particular, the extreme western section is occupied by the dunes of the Great Eastern Erg, also a continuation of the Algerian one, with its sands of recent wind transport. An integral part of the Precambrian base of Africa, the Tunisian Sahara is in reality only a flat monotone, rarely interrupted by reliefs of sedimentary origin; however, these give rise, in the southeast of the territory, to a weak ridge of limestone from the Cretaceous period, forming the Altopiano del Dahar (= ridge) and the Monti dei Ksour, which develop from N to S, almost parallel to the coast, culminating at 715 m just W of the town of Medenine. Of tabular conformation, weakly engraved by the so-called uidians, the Ksour Mountains finally yield to the E to another semi-arid flat expanse, Gefara (Al-Jifārah), but more widely developed in the contiguous Tripolitania (Libya). Tunisia faces the Mediterranean with 1150 km of very articulated coasts; by convention it is the Tunisian Capo Bon with the Sicilian one of the Lilibeo that divides the Mediterranean into the western and eastern basins.
From the border with Algeria to Capo Bianco the coast does not have many inlets; the sea can only creep between the rocky spurs that extend the mountains of Krumiria; almost non-existent in this stretch are the coastal plains, as well as lacking good anchorages. Between Capo Bianco and Capo Bon the landscape changes, both because alluvial deposits, especially in the Medjerda, have created new land (various places that, for example, faced the sea in Roman times are now inland), and because the sea it was able to penetrate deeply into the mainland (Gulf of Tunis). Vast are also the plains of the east coast, all of an alluvial character, originating from deposits of rivers that are now poor or only occasionally not completely dry; the shoreline, dunes and in many points bordered by lagoons, has the two vast indentations of Hammamet and Gabès. Numerous islands face the east coast: the Kuriate, in front of the city of Monastir, the Kerkenna in front of Sfax, the island of Djerba (Jerba), the largest (514 km²) of Tunisia, a large tabular fragment of limestone of the small gulf of Bou-Grara. Off the northern coast there are islands of modest importance, such as the volcanic La Galite, the Cani Islands, facing Biserta, and Zembra, in the Gulf of Tunis.