Though sometimes occurring as rounded bosses, as at Gebels Muelih, Selaia, and Faraid, granite typically forms rather jagged mountains, more especially in the south parts of the area; the mountains of Mishbih and Elba, for instance, abound in spiky peaks, while Qash Amir, the “Scragged Hill” of the Admiralty Chart, is an extreme example of this mode of weathering. The spikes are often made up of more or less rounded blocks piled one on another, the separation and rounding of the blocks being brought about by jointing and the more rapid weathering of the corners of the separated masses. Granite mountains, though sometimes white, are usually of a pink or red colour and are often named accordingly by the Arabs. In Ababda country, all mountains named _Hamrat_, as for instance Hamrat Wogud and Hamrat Mukbud, are composed of red granite or granitoid gneiss; while in Bisharin country the corresponding name _Adar_, as used for example in Adar Qaqa and Adar Aweib, has the same significance, both the names meaning _red_. The beds of wadis draining from granitic mountains, and plains adjacent to them, are invariably covered with a thick accumulation of coarse felspathic and quartzose sand derived from the weathering of the rock. This sand is quite firm to walk on, and in this respect forms a pleasing contrast to the finer wind-borne sand derived from the disintegration of sandstone. The granitic sand being generally white in colour (the redness of the felspars having largely disappeared in the process of weathering), the wadis in whose floors it is largely displayed are frequently named “Wadi el Abiad” (_abiad_ = white); there are numerous wadis called by this name, all possessing the common characteristic of draining from granitic mountains and consequently having a floor of granitic sand. Besides the great mountain-forming masses, granites also occur frequently in the form of dykes or veins, penetrating the gneisses, schists, and other rocks. Viewed as a whole, the granites of South-Eastern Egypt are characterised by their strongly acid composition. Though perfectly normal granites are found in many places, and a gradual passage into quartz-syenite may be occasionally traced, yet on the whole the rocks approximate to the aplitic and pegmatitic types in which quartz and felspar are associated with very small quantities of ferro-magnesian minerals. We may consider the granites as falling mainly into the following classes:— 1. Normal pink granite. 2. Red pegmatitic granite. 3. Aplite. 4. Biotite-granite. 5. Muscovite-granite. 6. Hornblende-granite. =PLATE XXII.= [Illustration: Ball.—Geography & Geology of South-Eastern Egypt. =ACID IGNEOUS ROCKS.= =PORPHYRITIC GRANITE.= Gebel Fereyid. =PEGMATITIC RED GRANITE.= Wadi Gemal. =BIOTITE-GRANITE.= Gebel Abu Hegilig. =HORNBLENDE-GRANITE.= Gebel Elba. =QUARTZ-FELSITE.= Near Gebel Kolaiqo. =QUARTZ-FELSITE.= Near Gebel Kolaiqo.