Tunisia

TUNISIA, a country of North Africa under a French pro tectorate, bounded on the west by Algeria, on the north by the Mediterranean, on the east by the Syrtis (Gulfs of Hammamet and of Qabes) and by the Italian territory of Libya from the sea to Ghadames, on the south by the Sahara (Southern Territories and Algeria). It reaches from 3o° to 37° 20' (Cap Blanc) N. lat., and from 35' to I I° 4o' E. longitude. The total area is somewhat less than 49,00o sq.m., of which about 21,500 sq.m. is Saharan territory beyond the Shott Jerid, while the remainder is Tunisia proper. The country is placed half way between the Straits of Gibraltar and the Suez canal and, with Sicily, forms the barrier between the eastern and western Mediterranean. This situation, to which ancient Carthage owed its greatness, together with the possession of nearly 900 miles of coastline, gives Tunisia special economic and political importance.

Structure and Relief.

The mountains are formed of Second ary and Early Tertiary rocks, while later Tertiary and Quaternary rocks cover the plains. The folds are Miocene in the main, as in the Atlas, but movement continued long after that period. There are numerous short discontinuous chains of varying orientation, and a number of small circular or elliptical domes.

The Northern Zone, continuing the Algerian coastal forest, includes Kroumirie and the Mogods; Numidian sandstone is a dominant element. It is bounded southwards by the Medjerda valley, which widens into the plain of Suk-el-Arba (Dakhla basin), an old lake basin filled with alluvium, then narrows to form the gorges of Bejaura, and finally enlarges into the great plain of Late Tertiary deposits that extends between Bizerta, Mateur and Tunis. The large Central Zone is nearly 180 m. long by 90 broad, extending from Tebessa to Cap Bon, and from the Medjerda to Sbeitla, and including the continuations of the Saharan Atlas of Algeria. South of the chains of Kef and Tebursuk are the central plateaux of Tunisia, the Mactar massif, a large Cretaceous dome partly covered by Lower Eocene deposits, including phosphatic marls, while the calcareous elements stand out as hammadas and kalaas, plateaux with abrupt sides, e.g., the Kalaa-es-Senan (4,108 ft.). In this massif folding is barely discernible. Next follow the chains of Thala, a projection of the main Tunisian ridge or Zeugitan chain which begins at Jebel Serdj, is continued in the Bargou and the Zaghouan (4,249 ft.), an important dome of liassic limestone with sharp features and almost vertical walls, and ends in Jebel Ressas and Bou-Kornefn, on the Gulf of Tunis. A

related fold forms the Cap Bon peninsula. Attached to the same system are the Chambi and Feriana chains. The Southern Zone includes the chains of Sidi Aich, of Gafsa, which include large phosphatic deposits (Metlaoui-Ain-Moulares), of Shott Fedjedj, in an elliptical curve from Tozeur to Qabes. Eastern Tunisia is occupied by large plains (less than 1,300 ft. above sea-level) which form 8o% of the surface of Tunisia and are the Byzacene of the ancients, the Sahel of Sous and Sfax, with their special climatic and vegetative features. Beyond the great depression of the Shotts Gharsa, Djerid and Fedjedj, which are in part below sea-level, are the calcareous platforms of the Matmatas and the Ourghammas (Jebel Demmer and Jebel Douirat), separated from the sea by the coastal plain of Jeffara.

Climate and Hydrography.

With a Mediterranean climate, Tunis shows less contrasts in its different regions than do the Tell, the steppe and the Sahara in Algeria. Here the Tell is, in places, half steppe, and the steppe half Tell. The average January tem perature at Tunis is 52.7° (max. ay. 59.7°, min. ay. 45.6°); the hottest month has an average of 79.2° (max. ay. 92°, min. ay. 66.4'). The winds are chiefly north-west in winter and north-east in summer; the rainy season runs from October to May, and the dry one from May to September; January is usually the rainiest month, but in the interior spring rains are rather important— summer rains are less exceptional. The distribution of rain is, however, highly irregular from region to region and from year to year; North Africa, in general, is in a zone of climatic discon tinuity, and a small change of the winds may mean great changes in rainfall. One zone gets more than 600 mm. of rain per annum, and this includes the massifs of Kroumirie and Mogods (Ain Draham, 5,384 ft.) ; the next zone, with 400-600 mm. of rain, includes central Tunisia, the valley of the Medjerda, Cap Bon and the region of Tunis (Tunis 404, Teboursouk 513, Kef ; a zone with 200-400 mm. south of the Tunisian ridge includes the region of Qairwan and the Sahel (Qairwan 289 mm., Susa 347, Sfax 209) ; a zone with less than zoo mm. in the south and extreme south (Qabes 18o mm., Gafsa 155, Medenine 136). The Tunisian ridge forms a climatic barrier; the north-western side is a part of the Tell (Tunisian-Friquia) ; the south-eastern slope belongs to the steppe region. In the Sahel, the olive prospers, in spite of the low rainfall, on account of nearness to the sea and importance of the dew. In the extreme south the influence of the sea still tem pers that of the Sahara.