About six kilometres below the well, Wadi Ghadir passes close north of Gebel Allawi, where there are some old gold mines. The Wadi Allawi, which with its tributary Wadi Lewewi drains the hilly country between Gebels Zabara and Sikait, enters Ghadir a little to the east of Gebel Allawi; both Allawi and Lewewi are very tortuous wadis, their names in fact meaning “crooked” in the Ababda tongue (Lewewi is a diminutive of Allawi).
Wadi Um Gamil, the next wadi entering the sea to the south, drains the hilly country south-east of Sikait. Very little is known about its course, the only part surveyed being the heads east of Gebel Sikait.
Wadi Gemal is the terminal portion, about sixty kilometres in length, of the main drainage channel from a basin nearly 200 square kilometres in area. With its numerous large feeders, the principal of which is Wadi Huluz, about eighty kilometres in length, the Wadi Gemal drains the Hafafit and Nugrus ranges of mountains on the north, and a great mass of high mountains, including Gebel Hamata, on the south. It will be convenient here to describe only the Wadi Gemal proper, leaving the great wadis which join to form it, and its major tributaries, for separate treatment.
The name Wadi Gemal is first given to the drainage at the point where Wadi Huluz turns sharply eastward in longitude 34° 39′.[89] At this point the country becomes more open than in the gorge-like Wadi Huluz. To the north is a mass of low granite hills, some of which have remarkable shapes, with a great deal of drift sand, while to the south are the higher dark hills flanking Gebel Um Suerab. Among these surroundings the wadi pursues a winding course, with a general north-easterly direction, receiving the Wadi Um Suerab lil Gemal and the Wadi Durunkat as tributaries from the south.
About six kilometres below the point of influx of Wadi Durunkat, on the right (south) side of Wadi Gemal, is a locality called Geli, where there are extensive ruins. A very remarkable rock in the middle of the main wadi marks the place whence a track leads south-east past the ruins and across the heads of Wadis Um Ghazal and Mukhatatat into the upper part of Wadi el Abiad.
Passing a remarkable bell-shaped hill (Gebel Um Regeba, rising to 571 metres above sea, the “mosque rock” of Floyer’s map) about four kilometres on the left, Wadi Gemal receives two small feeders coming from among the hills to the south, and then the important tributary called Wadi Hafafit enters from the north-west.
Below the point of influx of Hafafit, the Wadi Gemal becomes more narrow, and shut in by high hills. Near the meridian of 34° 49′ there are some ruins on the north side of the wadi, and a little further on the Wadi Nugrus, one of the largest tributaries of Wadi Gemal, enters from the north-west at a rather sharp bend. Further down, Wadi Gemal receives Wadi el Mukhatatat and Wadi Um Sueh from the south, and Wadi Um Heran and Wadi el Nasbia from the north. The Wadi Abiad, which next joins Wadi Gemal from the south, is an important feeder. Two kilometres below the mouth of Wadi el Abiad, the Wadi Um Kabu enters Wadi Gemal from the north-west, while nearly opposite to it is a small wadi, called Um Sellimi, in which there are water pools after rain. The wadi now curves more northward round the base of the double-topped hill mass called Madaret Um Gamil. Just beyond the northward turn a road[90] leads up a narrow tortuous gully in a north-westerly direction, passing close south of the hill summit and forming the most ready means of ascent of Madaret Um Gamil; the climb from the road at the top of the gully is only about 200 metres. The course of the Wadi Gemal to the sea has not been surveyed beyond four kilometres east of Madaret Um Gamil; it goes through low hilly country and enters the sea in about latitude 24°.
The fall of the Wadi Gemal averages about six metres per kilometre, being as low as four metres per kilometre in some places, and probably exceeding ten metres per kilometre where it emerges from the hills on to the coast-plain. It is interesting to note that the observations of level indicate a local increase of gradient above the place of influx of Hafafit and Nugrus. The Wadi Gemal is well supplied with trees, as are also almost all its tributaries with the exception of the sandy Wadi Hafafit.
Wadi Huluz is a long winding wadi, mostly shut in by high rock walls, draining the high mountains round Gebel Hamata and coursing north-east for a distance of over seventy-five kilometres to the point, near Gebel Um Suerab, where, turning sharply eastward, it enters more open country and takes the name of Wadi Gemal. The slope of Wadi Huluz averages fifty metres per kilometre for the first ten kilometres from its heads in the mountains. In the next ten kilometres the slope is much flatter, being twenty metres per kilometre. From twenty to forty kilometres from its head the average fall is only ten metres per kilometre, while still further down the rate of fall lessens till in the last reaches, just before entering the Wadi Gemal, it is only six and a half metres per kilometre.
The principal heads of Wadi Huluz are close to the south-east of Gebel Hamata, in a cul-de-sac formed by the high mountains of Gebel Hamata (1,978 metres above sea) and Gebel Ras el Kharit (1,661 metres). Here a number of steep gorges unite to form the main channel, which due south of Hamata has an altitude of 1,053 metres above sea-level. Following a winding course among the mountains as a rapidly falling valley with a sandy floor averaging 100 metres or more in width, it passes west of the great mass of Hamata, receiving the drainages from the north-east flanks of that mountain and from the north face of Gebel Um Hasidok. At its crossing the meridian of 35° it receives as a feeder the Wadi el Abiad lil Huluz, which drains the north face of Hamata and the south flanks of Gebel Abu Ghusun; draining mostly from granite country, this feeder has a floor of coarse granitic sand, from the whitish colour of which it takes its name.