69G THE UNIVERSE. 



A desert of sand i^ossesses a tranquil beauty; a desert 

 of stone is horrible. In the former the horizon develops 

 itself before our eyes, it is accessible and on the confines 

 of it are liberty and repose. In the other the horizon 

 seems impassable, death separates us from it, it is a dis- 

 ordered mass of rocks, burned by the sun, irregular and 

 rugged ; there is no practicable road, and it is easy to 

 imagine that a few hours' stay in such a frightful place 

 would prove fatal to the most robust traveller. The fright- 

 ful aspect of such a desert cannot be better compared than 

 to that which the old engravers gave of the sea in a 

 temj)est. It Avas thus that the desert of Assouan on the 

 borders of Nubia looked to us.^ 



And yet in arid deserts an oasis here and there, rich in 

 shade and coolness, rejoices the heart of the Arab, for it 

 is here that he quenches his thirst and rests his caravan. 

 Poetrjr, usurping the place of truth, has generally promul- 

 gated the belief tliat these spots only consist of a group of 

 palm-trees, protecting Avith their foliage some limpid desert 

 spring, where the camels slake their thirst on their halt. 



^ About 100 miles south of Assouan, occurs the remarkable desert of Korosko. 

 For the sjoace of two days' journey southwards from the town of Korosko (lat. 

 22° 35' N.), before reaching the plains called rivers without water and sea of sand, 

 the desert is covered with remarkable conical hills, among which winds the path 

 of the traveller. On the slopes of these hills lie moving sands, liable to be dis- 

 ])laced by every storm; the winds disperse them generally on the slopes ojiposed 

 to their course. These hills are formed of a quartzose sandstone, which gradually 

 becomes less solid in its composition as we advance towards the south. They are 

 not due to upheavals or convulsions of the eai'th's crust (though dislocations 

 caused by earthquakes may be traced in the valleys of erosion), but are formed 

 by horizontal irregular strata of different density, some only slightly knit, but 

 others united by argillaceous-ferrugineous cement, and more capable of resisting 

 the destructive effects of the atmosphere. The upper laj'ers are those that seem 

 less hard, but none of them are very homogeneous. From this geological forma- 

 tion there result the most picturesque effects: the sands are driven along the 

 bottom of the valleys, which they fill up horizontally to a certain height, leaving 

 e.xposed only the tops of the hills. — Imperial Gazetteer. — Tr. 



