CHAPTER VI. * * * * * =THE MOUNTAINS AND HILLS.= * * * * * It has been already mentioned (p. 19) that the principal mountain masses are divisible into ten main groups as follows:— i. The Migif — Hafafit — Nugrus — Hangalia — Zabara group; ii. The Abu Hamamid — Hamata — Abu Gurdi group; iii. The Um Gunud — Dahanib — Batoga group; iv. The Abu Dahr — Orga — Um Tenebda group; v. The Faraid group; vi. The Awamtib — Abraq — Dif — Aqab el Negum — Mishbih group; vii. The Gerf — Korabkansi — Abu Hodeid group; viii. The Meisah — Adar Qaqa — Is group; ix. The mountains of the Alaqi basin west of Gebel Adar Qaqa; x. The Elba — Shendib group; 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.