Sahara (place)

Sahara (Arabic Sah'ra), the vast desert region stretching from the Atlantic to the Nile, and from the S. confines of Morocco, Algeria, Tunis, and Tripoli S. to the vicinity of the Niger and Lake Tchad. It is usual to regard the Libyan Desert, lying between Egypt, the Central Sudan, and Tripoli, as a separate division. It was long customary to assert that the Sahara was the bed of an ancient inland sea. Since the French became masters of Algeria, they have completely revolutionized our knowledge. The surface, instead of being uniform and depressed below sea-level, is highly diversified, and attains in one place an altitude of fully 8,000 feet. There are still several extensive tracts as to which we have next to no information.

From the neighborhood of Cape Blanco in the W. a vast bow or semi-circle of sand dunes stretches round the N. side of the Sahara to Fezzan, skirting the Atlas Mountains and the mountains of Algeria. This long belt of sand hills varies in width from 50 to 300 miles, called Erg. The hills rise 300 feet though the average elevation is about 70 feet. They are composed of pure quartz sand, stationary in character, though constantly changing their outward form and configuration; and lie as a rule in parallel chains. Water is nearly always to be found below the surface in the hollows between the different chains and a few dry plants struggle to maintain a miserable existence. S. of Algeria, on the other side of the Erg, the country rises into the lofty plateau of Ahaggar (4,000 feet), which fills all the middle parts of the Sahara. Its surface runs up into veritable mountains 6,500 feet high, which are covered with snow for three months in the year. On the S. it falls again toward the basins of the Niger and Lake Tchad; there are mountain ranges along the E. side reaching 8,000 feet in Mount Tusidde in the Tibbu country, and a mountain knot in the oasis of Air, which reaches 6,500 feet. Mountainous tracts occur also in the W. between Morocco and Timbuctoo, but of inferior elevation (2,000 feet). These mountainous parts embrace many deep valleys, most of them seamed with the dry beds of ancient rivers, as the Igharghar and the Mya. These valleys always yield an abundance of water, if not on the surface in the watercourses, then a short distance below it, and are mostly inhabited, and grazed by the cattle and sheep and camels of the natives.

Another characteristic type of Saharan landscape is a low plateau strewn with rough blocks of granite and other rocks, and perfectly barren. These elevated stone fields -- called "hammada" -- alternate with tracts of bare flat sands, with broad marshes, where water has stood and evaporated, leaving salt behind it, and with extensive tracts of small, polished, smoothly-rounded stones. In many parts of the Sahara, especially in the valleys of the mountainous parts, in the recesses or bays at the foot of the hills, alongside the water-courses, and in the hollows of the sand dunes, in all which localities water is wont to exist, there are oases -- habitable, cultivable spots, islands of verdure in the midst of the ocean of desert. These oases mark the caravan routes between the Central Sudan States and the Mediterranean.

The Romans had colonies of military posts a long way S. in what are now desert regions; and both Herodotus and Pliny tell us that the elephant, the rhinoceros, and the crocodile, all animals that only live near abundant supplies of water, were common throughout North Africa in their day. None of the Egyptian inscriptions or animal sculptures represent the camel, nor to the Greek and Roman historians mention it either as being a denizen of North Africa. The camel is now the principal carrier across the Sahara, and must have been introduced since the begining of the Christian era.

The terrors of the desert sand storm have often been described. Thick deposits of Sahara quartz sand dust were discovered by the "Challenger" on the floor of the Atlantic a long way W. of the African coast. The sand in these dunes is so dry that in several places the tread of a camel or man will make the hill hum, or even thunder, as a vast quantity of it slips down to a lower level. The range of temperature is exceedingly great; often the thermometer falls from considerably more than 100 degrees F during the day to just below freezing-point at night. In the W. of the Sahara the daily average is 85 degrees in the shade in the month of May. Rain falls in parts of the Sahara, but in most districts after intervals of two to five years. After a fall of rain it is not unusual to see the river beds in the mountainous regions filled with foaming torrents. The atmosphere is so dry and clear that objects can be seen and sounds heard at a vast distance. Owing to the extreme dryness of the air, the Sahara is very healthy.

The plant life is very rich in the oases, the date palm, which has its home in these regions, being the principal ornament as well as the most valuable possession of these fertile spots. In the desert region the plant life is principally confined to tamarisks, prickly acacias and similarly thorny shurbs and trees, salsolacae, and coarse grasses. The animals most commonly met with include the giraffe, two or three kinds of antelope, wild cattle, the wild ass, desert fox, jackal, hare, lion, ostrich, desert lark, crow, viper, python, locusts, flies. The people keep as domestic animals the camel, horse, ox, sheep, and goat.

The human inhabitants, who are estimated altogether at between 1,500,000 and 2,500,000, consist of Moors, Tuareg, Tibbu, Negroes, Arabs, and Jews. The Tuareg are great traders and control the principal caravan routes. The Tibbu, who number about 200,000, and are regarded as being ethnically intermediate between the Berbers and the Negroes, occupy the oases bewtween Fezzan and Lake Tchad. The Arabs of pure stock are very few.

The boring of artesian wells, and with the water so obtained irrigating the soil in the vicinity, was apparently known to the ancients, and has been prosecuted by the French with great energy since 1856. By 1890 they had made a string of these wells from the cultivated districts of Algeria as far as Tugurt, on the edge of the desert S. of Biskra. Water is generally found at depths varying from 10 to 300 feet, in great abundance, and around them date palm groves and orchards support agricultural communities. A telegraph line across the desert S. to Timbuktu was opened in 1906.