The highest point of Gebel Gerf had been singled out as a triangulation station from far to the north, while approaching the mass from the Wadi Hodein. It was eventually reached from the west side after leaving Gebel Korabkansi, the approach being made by ascending the Wadi Eirahimib, and going over the pass at its head (830 metres) into one of the heads of Wadi Um Reddam, turning round a spur and ascending another of the heads of the same wadi. The camp, placed as high up the wadi as possible, lay about 1,500 metres west of the beacon, at an altitude of 820 metres. The climb of nearly 600 metres to the summit occupied three and a quarter hours, and was free from serious difficulty, though involving some tiresome traversing of connecting ridges. The summit of Gebel Gerf is often wrapped in clouds for weeks together in winter, and cold northerly gales are prevalent. I found it necessary to remain on the summit for no less than twenty-one days and nights in January 1907, in order to obtain the observations necessary, and the discomfort due to enforced inaction and piercingly cold winds was considerable. The top of the mountain is a narrow ridge on which there is barely standing room for an instrument, but about 100 metres southward along the ridge from the beacon there is a slight broadening where a small tent may be pitched by hitching the ropes round rocks instead of tent-pegs.
On a clear day, the view from the summit of Gerf is a magnificent one. The numberless rugged ridges and peaks of the Gerf mass itself stretch for miles around, and out beyond, in every direction except to the east, one can see the more distant mountains. In the north, the most striking features are the distant spikes of Gebel Faraid, and still further off one may discern the blunter forms of Gebels Abu Gurdi, Hamata, and Abu Hamamid, 180 kilometres away. To the east is the coast-plain, with the granite peaks of Gebel Hamra Dom breaking the monotony. To the south-east one may see the great peaks of the Elba and Shendib mountains, 130 kilometres away, though these are often hidden by mist when everything else is clear. To the south, one looks out, over the gneiss boss of Gebel Um Rasein, to the mountains, rising rank behind rank, of Medarai, Abu Hodeid, Adar Qaqa, and Is; while a little to the left of the last-named one may see the double-headed granite mass of Gebel Obkeik in the Sudan, more than 100 kilometres distant, towering above the intervening Egyptian mountains. The panorama visible to the south and south-east is shown drawn to scale from theodolite measurements in the lower figure on [Plate XVI] (p. 206). To the south-west, one can make out the principal mountains of the Alaqi basin, while to the west the mountains of Korabkansi, Shabih, and Mishbih are conspicuous features.
The north portion of the Gerf mass, sometimes called Gebel Meneiga, is drained by the Wadi Kreiga, which is a tributary of Wadi Hodein. One of the principal feeders of Wadi Kreiga is the stony Wadi Meneiga, important as containing perennial springs of good water, easily accessible to camels. The eastern and southern parts of the mass are drained by various feeders of Wadi Shab, the principal of these feeders being Wadi Shellal el Sharqi, Wadi Muqur, Wadi Baaneit, Wadi Diqdib, and Wadi Sherefa el Sharqi. The Wadis Muqur, Baaneit, and Diqdib, all contain wells or springs, that in Wadi Diqdib being right in the heart of the mountain mass, while the others are nearer to its periphery. The western flanks of the Gerf mass are drained by the feeders of Wadis Feqoh and Madi, the principal being the Wadis Sherefa el Gharbi, Eirahimib, Shellal el Gharbi, and Korbiai. The Wadi Sherefa el Gharbi is important as leading to the Sherefa Pass (907 metres) which forms a direct road from Bir Sararat Seyet to the well of Um Rasein, while Wadi Korbiai contains an excellent well at its head, easily reached by camels.
Gebel Dreb is a many-peaked mass of mountains covering some sixty square kilometres, situated south-west of the Gerf mass, from which it is separated by the Sherefa Pass. Its highest peak is 1,293 metres above sea, but there are numerous other peaks of but little inferior altitude. Its south-western portion looks on to the plain at the head of Wadi Feqoh, while to the south-east it is separated from Gebel Medarai by an easy pass leading from the head of Kwat Hewah westwards into the head of Wadi Kreim, a tributary of Wadi Feqoh. Another pass is said to exist leading from Wadi Sherefa el Sharqi into the head of Wadi Dreb, where there is a well called Bir Bint el Dreb.
Gebel Medarai, the next mountain mass to the south-east, is separated from Gebel Dreb by the pass into Wadi Kreim above referred to, while at its south faces it is separated from Gebel Abu Hireiq by another pass leading from one of the heads of Wadi Medarai westwards into the Wadi Kirwau, a tributary of Wadi Feqoh. The highest point of Gebel Medarai, marked by a large cairn, is in latitude 22° 30′ 58″, longitude 35° 12′ 5″, and rises to 1,299 metres above sea-level. The north faces of the mass are drained by Kwat Hewah, a tributary of Wadi Shab; the eastern flanks by Wadi Medarai, a tributary of Wadi Ibib, while the western faces drain by various feeders into Wadi Feqoh.
Gebel Abu Hireiq, the mountain-mass next south of Medarai, extends eastwards, as a broad tract of many high ridges, almost to the gneiss-boss of Um Rasein, while to the south it is united with Gebel Abu Hodeid. The highest point of Abu Hireiq is 1,319 metres above sea. Its eastern flanks are drained by tributaries of Wadi Ibib, while the western parts drain into Wadi Feqoh.
Gebel Abu Hodeid, which forms a higher southward extension of Gebel Abu Hireiq, is really two ranges with the Wadi Abu Hodeid draining between them. The western range is the higher, its summit, marked by a beacon in latitude 22° 23′ 18″, longitude 35° 14′ 9″, being 1,482 metres above sea. The highest point of the eastern range is 1,256 metres above sea. The south termination of this eastern range is a very conspicuous rounded peak of granite, 992 metres above sea, called Abu Hodeid Ogla, which forms a good landmark for travellers in making the wells of Abu Hodeid; the wells lie west of this peak. The south parts of the Abu Hodeid mountains are drained by the Wadis Shinai, Delawet, and Abu Hodeid, all feeders of Wadi Hasium, and all leading to important water sources. The eastern faces are drained by Wadis Abu Hireiq and Tikraneib, which are likewise feeders of Hasium, while the western flanks are drained by feeders of Wadi Feqoh. The broad opening where Wadi Hasium passes to the south of the range makes a natural division separating the mountains of Abu Hodeid from those of the Adar Qaqa group.
Gebel Mansur Diab, a dark mountain, 1,091 metres high, lying six kilometres west of Gebel Abu Hodeid, is not often visible from the east, being hidden by the higher ranges in front of it; but it forms a conspicuous landmark to any one approaching from the west.
To the south of Gebel Mansur Diab, between the heads of Wadi Feqoh and Wadi Hasium, are some other mountains of considerable height, the positions of whose summits were fixed by triangulation, but which were not closely approached. These are Gebel Hadal Derqa (1,108 metres), which as seen from the north appeared like a hog-backed dark ridge with a conical semi-detached hill at its south-east end; and Gebel Hilwit Hasium, which appeared to consist of two separate peaks some three and a half kilometres apart, the higher or north-east one rising to 1,037 metres, the south-west one to 952 metres above sea.
Gebel Korabkansi is a rugged mass of dark serpentine peaks and ridges occupying a nearly isolated position some twenty kilometres west of Gebel Gerf. Its highest point, marked by a triangulation beacon, is situated in latitude 22° 39′ 16″, longitude 34° 59′ 55″, and rises to 1,230 metres above sea. The main mass is flanked by lower hills to the north and south, but is more open to the east and west. It is drained entirely by feeders of Wadi Feqoh, the most important of these being the Wadi Gemal. The upper portion of Wadi Gemal is called Wadi Seyet, and is important as containing a well, Bir Sararat Seyet; the well is about five kilometres north-east of the main peak, at a place where the wadi cuts through the flanking hill range. For the ascent of the mountain, it is best to turn westward from near the well, and follow up one of the tributaries of Wadi Seyet which leads right into the heart of the mountain; here a camp can be pitched at 765 metres above sea-level, and the ascent of 465 metres to the summit, from which there is a grand view, can be accomplished in less than two hours. The ascent and descent require some care, owing to the steepness of the slopes (the observed depression angle from summit to camp was 29¼°) and the rottenness of the rock, which comes away in lumps at a touch. The accumulated debris, consisting of small fragments of serpentine, sets at just the angle of repose, so that in coming down one can stick one’s feet firmly in the mass and slide down with it for a hundred metres or more without exertion, taking care only not to be shot over a sudden drop of the face. The rocks are highly magnetic, and the compass is much disturbed anywhere on or about the mountain. The mass of high hills which forms the southward extension of Korabkansi, with peaks and ridges rising to over 900 metres above sea-level, is called Gebel Wadhait. It is drained on the north by Wadi Wadhait, a tributary of Wadi Seyet, and on the west by the Wadi Kamoyib, a tributary of Wadi Feqoh.