Note 6 — STEPPES AND DESERTS.

p. 3.—“The Desert near the basaltic mountains of Harudsh.”

Near the Egyptian Natron Lakes, (which in the time of Strabo had not yet been divided into six reservoirs), there is a range of hills which rises steeply on the northern side, and runs from east to west past Fezzan, where it finally appears to join the chain of the Atlas. It divides in north-eastern Africa, as the Atlas does in north-western Africa, the inhabited maritime Lybia of Herodotus from the land of the Berbers, or Biledulgerid, abounding in wild animals. From the limits of Middle Egypt the whole region south of the 30th degree of North latitude is a sea of sand, in which are dispersed islands, or Oases, containing springs of water and a flourishing vegetation. The number of these Oases, of which the ancients only reckoned three, and which Strabo compared to the spots on a panther’s skin, has been considerably augmented by the discoveries of modern travellers. The third Oasis of the ancients, now called Siwah, was the Nomos of Ammon; a residence of priests, a resting place for caravans, and the site of the temple of the horned Ammon and the supposed periodically cool fountain of the Sun. The ruins of Ummibida, (Omm-Beydah), belong incontestibly to the fortified caravanserai at the temple of Ammon, and therefore to the most ancient monuments which have come down to us from the early dawn of civilization. (Caillaud, Voyage à Syouah, p. 14; Ideler in den Fundgruben des Orients, Bd. iv. S. 399–411).

The word Oasis is Egyptian, and synonymous with Auasis and Hyasis (Strabo, lib. ii. p. 130, lib. xvii. p. 813, Cas.; Herod. lib. iii. cap. 26, p. 207, Wessel). Abulfeda calls the Oases, el-Wah. In the later times of the Cæsars, malefactors were sent to the Oases; being banished to these islands in the sea of sand, as the Spaniards and the English have sent criminals to the Falklands or to New Holland. Escape by the ocean is almost easier than through the desert. The fertility of the Oases is subject to diminution by the invasion of sand.

The small mountain-range of Harudsh is said to consist of basaltic hills of grotesque form (Ritter’s Afrika, 1822, S. 885, 988, 993, and 1003). It is the Mons Ater of Pliny; and its western extremity or continuation, called the Soudah mountains, has been explored by my unfortunate friend, the adventurous traveller Ritchie. This eruption of basalt in tertiary limestone, rows of hills rising abruptly from dike-like fissures, appears to be analogous to the outbreak of basalt in the Vicentine territory. Nature often repeats the same phenomena in the most distant parts of the earth. In the limestone formations of the “white Harudsh” (Harudje el-Abiad), which perhaps belong to the old chalk, Hornemann found an immense number of fossil heads of fish. Ritchie and Lyon remarked that the basalt of the Soudah mountains, like that of the Monte Berico, was in many places intimately mixed with carbonate of lime,—a phenomenon probably connected with eruption through limestone strata. Lyon’s map even mentions dolomite in the neighbourhood. Modern mineralogists have found syenite and greenstone in Egypt, but not basalt. Possibly the material of some of the ancient Egyptian vases, which are occasionally found of true basalt, may have been taken from these western mountains. May “Obsidius lapis” also have been found there? or are basalt and obsidian to be sought for near the Red Sea? The strip of volcanic or eruptive formations of the Harudsh, on the margin of the African desert, reminds the geologist of the augitic vesicular amygdaloid, phonolite, and greenstone porphyry, which are only found at the northern and western boundaries of the Steppes of Venezuela and of the plains of the Arkansas, as it were on the hills of the ancient coast line. (Humboldt, Relation Historique, tom. ii. p. 142; Long’s Expedition to the Rocky Mountains, vol. ii. pp. 91 and 405.)