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AEABIA
AEABIA
on tbe S. side, the most important of the iBlands ^^'hich lie ofi' Arabia.
The ^eolo^cal character of A. is thus described by Mr. Doughty : 'The constitution of the Arabian peninsula appears to be a central stack of Platonic rocks which are ^ranited uith traps and old basalts, whereupon are laid sandstones (continuous witJj those of Petra, and probably "cretaceous"), and limestones (sometimes with dints) overlie the sandstones. Ne\^er rocks are the volcanic, and namely of the vast " harrahs " : the flint land of eravel (upon limestone with flint veins) that is A. Petrjea, in which were found flint instruments (as those of Abbeville) by Mr. Doughty at Man, 1S76 ; and ancient flood soil, block drift, loams or clays in the volleys and low j^rounds.'
The land won from the sea constitutes the low- lands (called by the Arabs Tihamah), which fringe the peninsuJa, and beyond which there rise ranges of mountains on all three sides. On the N. the great Nefud, which succeeds to the stony plain, occupies the centre of the peninsula, with a greatest breadth of 150 miles, and a greatest length of 400 miles. Of this wilderness of red sand the most accurate description has been given by W. H. Blunt (in Lady IJlunt's Pilgrimage to Nejd, vol. ii. app. i.). Far greater, however, is the untrodden desert (Ahkaf) which cuts off Central A. from the E. and S.E. provinces. The sand of these wastes has peculiarproperties, which, according to Blunt, render them as dillerent from other deserts as a glacier is from a mass of snow. To the S. of the former Nefud rises the Jebel Aja, a red granite range, stretching E. by N. and W. by S. for some 100 miles, with a mean breadth of 10-15 mUes, and rising to a height of 5600 ft. (Blunt, I.e.). To similar heights do the movmtains rise which shut in the peninsula on the W. and E. sides ; Wellsted gives the measurement 6500 ft. for the peak of Mowilah (S. of the Gulf of Akabah), while 9000 ft. is the height of some portions of the Jebel Akhdar, or Green Mountains, which tower over Oman in the E. (according to the latest researches of Mr. Theodore Bent, Cuntemp. Rev. Dec. 1895). To the same height, according to W. B. Harris [A Journey through Yemen, 1894), do the passes by which Yemen is entered from the S. rise in places j and if the measurements of this writer are correct, the plateau of central Yemen, in the S.E., has an average altitude of 8000 ft. Farther to the E. this southern range sinks till, where it separates the incense country from the desert (about 55° long. E. of Greenwich), its eleva- tion is not above 3000 ft.
Between the mountains and the Nefud in North A. lies El-Hisma, the great sandstone country, described by Doughty as 'a forest of square- built platform mountains, which rise to 2000 ft. above tlie plain ; the heads may be 6U00 ft. above sea-level.' Between lat. 26° and 20° vast tracts form what are called harrahs, beds of basalt, where the sandstone is covered with lava. The most northerly of these volcanic platforms, called'Uwayrid, stretches for 100 miles in length, its middle point being about 120 miles from the Red Sea. It is thickly strewn with the craters of extinct volcanoes, so thickly that in places as many as thirty can be seen at once. The highest cf these peaks, called Anaj, is 7600 ft. About lat. 16° this phenomenon is repeated. We owe descrip- tions of it to Douglity and Glaser.
Of the rivers of A. none are navigable ; few are perennial, or reach the sea. Some such, however, nave been marked in South A. by the travellers Wellsted and W. B. Harris. Most of them dis- ai'pear in the sand at some part of their course. Instead of a river system tliere is a system of wadys, great receptacles for the water brought down by the mountains, of which the surface for large portions of the year is dry, but where water can be got by digging. Such in North A. is the Wady Birhan, which bisects the country in a line parallel with the Euphrates; in Central A., tlie Wady el- Dawasir and Wady el-Kummali, N. and S. of
Yemamah respectively, both issuing in the Perg. Gulf— with the former of these, or with one great tributary of it, Glaser {Shizze, ii. p. 347) would identify the Biblical Pishon ; and the Wady el- Humd, first traced by Doughtj, which traverses the Hijaz, and issues m the Red Sea. At Saihut (lon^. 51°), on the S. coast, there issues the Wady of Hadramaut, once probably an arm of the sea, which in its course of 100 miles receives s series of wadys that drain the moimtains behind it ; while the mountains of Yemen proper are drained by wadys called Maur, Surdud, Siham, Kharid, etc., of which the course was traced by Glaser ('Von Hodaida nach Sana,' in Peterraann's Mittheilungsn, 18S6).
The classical writers divided A. into A. Felix, A. Petma, and A. Deserta. This division was based on the pohticat condition of A. in the Ist cent, a.d., the first being free, the second (inclusive of Idumaa) subject to Rome, the third subject to Persia. In the native divisions different principles, u Sprenger {Alt. Geog. Arab p. 9) has pointed out, have been confused. According to a tradition which he quotes, Mohammed, standing at Tebuk (about 2»" C, ST 40'), said that all to the N. wa« Sham (lit. the left, ordinarily used for Syria), all to the S. Yemen (the right). According to this, the name for the province of Mecca, Hijoz (lit. * the barrier ') would mean the land between Sham and Yemen. More probably it meant the 'middle region' between the lowlands and the Nejd (highlands). These last, then, are terms of ph\^ical geography ; and as those by whom they were applied had no accurate instruments for determining