Next, turning to the north down the narrow declivity called _Nakb Hawi_, the "windy pass," of which the stupendous _granite_ walls or cliffs elevate themselves to about 800 feet, passing to the west end of _Wadi Solaf_, where it meets _Wadi Firan_ and _Wadi-el-Sheikh_, and following the last valley as far as _El Szaleib_, that ascent is attained. There the formation consists of _granite_, on the upper beds of which run layers of _red felspar_. North-east of _Wadi-el-Ush_ is situate _Gebel Sheyger_, which affords some native _cinnabar_. The three principal passes leading from the sandy Debbet-el-Ramleh on to the great desert over the Tyh range, are, _El Mureikhi_ near the centre and near _Gebel-el-Egmeh_; then _El Warsah_, said to be of too rapid an ascent for caravans; and the third, which is most to the west, _El Rakineh_ (the painted.) Afterwards, at some distance to the NW., is the valley opening past _Ras Wadi Gharandel_, that has already been described. Proceeding, again, across the plain El Ramleh, and over the pass Mureikhi on to the Desert-el-Tyh, in the approach to the castle of _Nakhl_, on the east, a few miles off, low _chalky_ hills appeared; and in places there were holes wherein _rock-salt_ had been dug. The water at Nakhl is brackish, and the ground chalky, covered with loose pebbles. _Wadi Nesil_ was observed to be overgrown with green shrubs. _Gebel-el-Thughar_, signifying "the mouths," presents a mountainous tract, in which followed a valley with _calcareous_ hills: here deep sands were lodged, and large insulated rocks of a porous _tufa_, called by Burckhardt _tufwacke_, lie scattered in many places. "The termination of the vast gravelly plain we had been crossing from _Nakhl_ was now at hand; but we could yet see it spreading out wide to our left, the mirage giving its distant portions the appearance of a succession of blue lakes; directly in front were the mountains which close it in; and far to the right we could see, stretching away, a still higher range running to the north, and on the left the tops of the mountains about Wadi Gharandel, the _Taset_ (cup) _Soddur_ being conspicuous afar. We entered these mountains by a slight ascent, which struck soon after the head of a long winding valley descending towards Suez: the immense plain we had traversed, floated away in mist, and we had now done with the plateau of the Great Desert."[15] Footnote 15: _Bartlett's_ "Forty Days in the Desert," p. 167. Thence a plain, which is below the level of the Desert-el-Tyh, and covered with moving _sands_, extends as far as the sea-shore. These _sands_ are collected by the winds, in many spots, into hills 30 or 40 feet high. The wells at _Mabuk_ afford good water by digging to the depth of 10 or 12 feet.