The actual width of the plateau varies from 120 kilometres between Abu Sighawâl and the scarp above Waled Hallaf, to 200 kilometres between Beris and Esna. The maximum elevation above sea-level is about 550 metres on the latitude of Esna, and on the whole the plateau has a fairly general slope to the north. As already mentioned, several distinct types of country, depending on the nature of the rocks constituting the surface strata, are met with. Smooth, hard, level plains, formed of a superficial layer of weathered limestone covered by a brown veneer of insoluble flint and cherty fragments, alternate with bare rugged rock desert of hummocky limestone. The sombre level or gently undulating flint-covered plains, frequently spoken of as ‘serir’ by the Arabs, have ideal surfaces for travelling; the light-coloured hummocky country, often called ‘kharafish,’ is in its most developed form made up of innumerable elongated hillocks, every portion of the exposed rock-surfaces being deeply scored; the furrows are separated by upstanding edges, often so sharp and knife-like as to be capable of injuring the feet of man and beast. The hillocks are separated by deep troughs half buried in drift-sand, all lying parallel, in the direction of the prevailing winds, so that progress in a latitudinal direction through this type of desert is a slow and tedious undertaking. Both types of country are equally desolate and barren, scrub of any description being of the rarest occurrence, except after local thunderstorms. Another type of country, to which we have already briefly alluded, is the curious desert-surface called El Botîkh (the water-melons), which results from the weathering of certain bands of the Lower Eocene formation containing numbers of large globular concretions; these, it may be mentioned, often lie so thickly strewn on the surface as to actually obstruct the passing caravan. Kharga is connected with the oasis of Dakhla to the west by two roads, the lower and more southerly, known as the Derb el Ghubbâri, being the one most frequently used. This road, by taking a wide sweep to the south, avoids the intervening plateau altogether, so that the fatiguing ascent and descent are avoided. After leaving Kharga village the route leads past a group of wells, known as Ain Khenâfish, distant some 6 kilometres; thence it lies over wide-stretching plains of sandstone, leading up to the more broken country formed by the foot-hills of the towering plateau, which is always plainly visible on the north side of the road. The distance to Tenîda, the most easterly of the Dakhla villages, is 143 kilometres by the Derb el Ghubbâri.