while there are numerous more or less isolated mountains and hills lying outside these principal masses. In the present chapter a more detailed account will be given of each of the main groups, taking them in order from north to south, the principal outlying hill-masses being considered along with the mountain group to which they are in greatest proximity. It may be remarked that the geographical positions of all the principal peaks are tabulated in [Chapter III.]
The Migif — Hafafit — Nugrus — Hangalia — Zabara Group.
The highest mountains of the group (see the detailed map on [Plate VI]) form a close cluster, round Gebel Nugrus (1,505 metres) as a centre, between latitudes 24° 40′ and 24° 55′, while other more or less detached masses are scattered to the north and west. A striking feature of the central cluster is the tendency to extension in a north-west and south-east direction, which is specially marked in the Hafafit and Hangalia ranges.
Gebel Nugrus, the central and highest mountain of this northerly group, is a great boss of red granite rising to a height of 1,505 metres among schists and gneisses. It is an almost isolated mass, for though the Hangalia and Hafafit ranges close in on it from either side, there are passes both east and west of it by which a circuit of the mountain can be made. In plan, it is a pear-shaped mass, about fourteen kilometres in length by six kilometres in width, having its long axis north-west and south-east. Gebel Nugrus is on the main watershed; its north parts are drained Nilewards by the Wadi Hangalia and other feeders of Wadi Gerf, while the drainage from its south portion passes by the Wadi Nugrus and Wadai el Nom to the Wadi Gemal and thence to the sea. The ascent of the mountain was made from a camp about four kilometres west of the summit, at the top of the pass leading into the stony head of Wadi Nugrus. The divide here is flat and sandy, at an altitude of 691 metres above sea-level, so that the ascent from camp to summit was 814 metres. Striking eastwards over the lower ridges which flank the main back-bone of the mountain, the summit was reached after a climb of nearly four hours. When ascended from this side, there appear to be two main peaks, of which the further one, marked by a beacon, is the triangulation point; the best way up is between the two peaks, as the passage from one to the other is very rough and steep. Though tiring, the climb is not very difficult. The top of the mountain (see [Plate VII]) is a mass of great rounded knobs of granite, on which a suitable place for setting up instruments was only found after some searching. The beacon, in latitude 24° 48′ 34″, longitude 34° 35′ 47″, is on a rounded eminence not large enough to receive an instrument, so that eccentric observations were necessary; the distance between the eccentric point of observation and the beacon had to be found by a subtense method, as the roughness of the mountain top rendered any process of chaining or taping impossible. The view from the summit is very fine. To the west, one sees the pinnacles of Migif and the nearer long range of Hafafit; to the north-east is the black cone of Atut; northward, seen over a sea of hills, is Igli; to the east is the high ridge of Hangalia, culminating to the south in Gebel Zabara.
The sea is visible to the north-east and east, but the sea horizon was obscured during the three days I spent on the summit by banks of clouds. These cloud banks simulated the sea horizon very closely, their upper surface appearing perfectly horizontal. They caused a peculiar phenomenon at sunrise, producing the optical effect of two suns rising one after the other owing to the refraction through the cloud. The first thing seen was a blood-red image of the sun rising over the true sea horizon, which was only thus discovered, the sun being seen through the cloud; about three minutes later, when a little more than half the blood-red disc had risen, the true sun rays flashed out from another and much brighter segment appearing over the top of the cloud, so that parts of two sun disks were seen at once, quite separately, one over the other.
Before descending from the mountain, I went along the ridge south-east and north-west of the highest point to get plane-table stations; in either direction progress along the top is extremely difficult. To the north-west it appeared as though the way would be easier by keeping on the east side of the ridge, but in reality this was not so, as the slope was so steep and smooth that some stretches could only be got over by wriggling along with as much as possible of one’s body in contact with the rock. The descent from the north-west end of the ridge to camp was difficult and rather dangerous in places. It is possible that a better way up the mountain could be found from the pass at the head of Wadi Hangalia, on the opposite side to where I started; that pass is 120 metres higher than the west one, so that the total climb would be lessened by that amount, and the horizontal distance is about the same.
Gebel Hafafit is a very long range, chiefly of gneiss, running in a nearly straight line south-eastward for over thirty kilometres. Its highest peaks are at its north end, where they are not very much lower than those of Gebel Nugrus; the heights decrease gradually further south. Half way down the range is a very conspicuous peak called Um Moghar, 860 metres above sea, while another well marked summit, the only one which I climbed, exists near the south end and rises to 744 metres. This last-named point is marked by a beacon, in latitude 24° 35′ 32″, longitude 34° 45′ 22″. On either side of the main back-bone of Hafafit are high flanking ridges. The drainage of Hafafit practically all flows seaward by the Wadi Gemal; the west faces are drained by Wadi Hafafit, and the east ones by Wadi Nugrus.
East of the south part of Gebel Hafafit are some remarkable bosses of granite, of which the chief, Gebel Abu Had, rises to 633 metres above sea, and is a landmark for Bir Abu Had. Another remarkable hill, closer in to Hafafit and the Wadi Gemal, is shaped like a bell with a handle on the top; this hill, which forms a good landmark, is called Gebel Um Regeba, and its summit is 571 metres above the sea.
PLATE VII.
