Captains Irby and Mangles, the _first_ Europeans who ascended Gebel _Harun_, thus describe "the view from the summit." It "is extremely extensive in every direction; but the eye rests on few objects which it can clearly distinguish, and give a name to, although an excellent idea is obtained of the general face and features of the country. The chain of Idumean mountains, which form the western shore of the Dead Sea, seem to run on to the south, though losing considerably in their height. They appear in this point of view, barren and desolate. Below them is spread out a white sandy plain, seamed with the beds of occasional torrents, and presenting much the same features as the most desert parts of the Ghor. Where this desert expanse approaches the foot of Mount Hor, there arise out of it, like islands, several lower peaks and ridges, of a purple colour, probably composed of the same kind of _sandstone_ as that of Mount Hor itself, which, variegated as it is in its hues, presents in the distance one uniform mass of dark purple. Towards the Egyptian side there is an expanse of country without features or limit, and lost in the distance. The lofty district which we had quitted in our descent to Wadi Mousa, shuts up the prospect on the south-east side; but there is no part of the landscape which the eye wanders over with more curiosity and delight than the crags of Mount Hor itself, which stand up on every side, in the most rugged and fantastic forms, sometimes strangely piled one on the other, and sometimes as strangely yawning in clefts of a frightful depth." Under the term _Nabathæan Chain_, or the chain of the mountains of Edom, I have restricted those mountains beginning north of 30° N. Lat., and which then tend round northward, by the east of Petra. They are the loftiest on the east, attaining probably to an altitude of 3000 feet above the Wadi-el-Araba. This chain presents to the view, on the east, long elevated ranges of _limestone_, sometimes with _flints_, but of more easy slopes, _without_ precipices, being smooth and rounded. Further still to the east, the high plateau of the Great Eastern Desert--of which _El Nejd_ is a portion--stretches out to an almost indefinite extent. To the west and north, and around Mount _Hor_, lofty party-coloured _sandstone_ ridges and cliffs prevail; then succeed high masses of _porphyry_, constituting the body of the mountains, but _lower_ than the _sandstone_. And, lastly, more northwards, the chain sinks down into low hills of _argillaceous_ rock, or of _limestone_. The entire breadth of the _Seir_ range seems not to exceed eighteen English miles, between Wadi-el-Araba and the Eastern Desert; whilst that of the more northern, or _Nabathæan chain_, does not exceed twenty-two miles between those districts.