In place of the broad fields and mountains to which we have been accustomed, the river here flows in a basin formed by low, precipitous hills, and is broken by innumerable rocky islets on different levels, which form the series of rapids and little cascades which give the cataract its name. These little islets are formed by a collection of boulders of red granite filled in with silt, and have a very strange effect, for the boulders are rounded by the action of the water, which, combined with the effect of the hot sun, has caused the red stone to become coated with a hard skin, black and smooth to touch, just as though they had been blackleaded.
Many of the islets are simply rocks of curious shapes which jut out of the water; others are large enough to be partially cultivated, and their little patches of green are peculiarly vivid in contrast with the rock and sand which form their setting.
The scenery is wildly fantastic, for while the rocks which form the western bank are almost entirely covered by the golden sand-drifts which pour over them, smooth as satin, to the water's edge, those on the east are sun-baked and forbidding, a huge agglomeration of boulders piled one upon the other and partially covered by shingle, which crackle under foot like clinkers; between are the islands, many crowned by a hut or pigeon-cote, and with their greenery often perfectly reflected in the rapidly flowing water.
Though navigation here is difficult, and a strong breeze is necessary to enable vessels to ascend the river, boat sailing is a popular feature of European life in Assuan, a special kind of sailing-boat being kept for visitors, who organize regattas and enjoy many a pleasant picnic beneath the shade of the dôm palms or mimosa-trees which grow among the rocks.
In the old days the great excursion from Assuan was by water to the "Great Gate," as the principal rapid was called, often a difficult matter to accomplish. To-day the great dam has replaced it as the object of a sail.
This is the greatest engineering work of the kind ever constructed, and spans the Nile Valley at the head of the cataract basin. It is a mile and a quarter in length, and the river, which is raised in level about 66 feet, pours through a great number of sluice-gates which are opened or shut according to the season of the year and the necessities of irrigation or navigation.
Behind, the steep valley is filled, and forms a huge lake extending eighty miles to the south, and many pretty villages have been submerged, while of the date-groves which surrounded them the crests of the higher trees alone appear above water. The green island of Philæ also is engulfed, and of the beautiful temple of Isis built upon it only the upper portion is visible.
Below the dam activity of many kinds characterizes the Nile, as does the sound of rushing water the Cataract basin. Above, silence reigns, for the huge volume of stored water lies inert between its rugged banks.
One's first thought is one of sadness, for everywhere the tree-tops, often barely showing above water, seem to mourn the little villages and graveyards which lie below, and as yet no fresh verdure has appeared to give the banks the life and beauty they formerly had.