The flat on the right bank at Dakke (172 miles north of Wadi Halfeh) was found to be not quite 100 feet above the level of the river; and, as usual, it was covered with the same soil and loose stones noticed at Derr, Korosko, and the last-named locality. I traced the Cyrena fluminalis* among the natron-soil for upwards of a mile inwards, and the Bulimus for another half-mile to several hills, and to a desert plain which was covered with drifted sand. No trace of Shells could be met with at corresponding heights on the left bank. The alluvium extends from the river for a long way beyond the Temple of Dakke, which, like that at Maharraka, is built upon it. I may here remark that neither the banks of alluvium now forming nor these more ancient accumulations seem to contain many Shells; it is only on ancient bottoms, where the currents were not strong, and depositing much, that these remains appear most abundant. The great alluvial heaps seem to have been deposited by rapid currents, which may not have carried Shells along with them. I have often been struck with the absence of any traces of animal structures in the alluvial banks of the river, which fact I cannot account for in any other way. The above-mentioned high levels were traceable along the slopes at broken intervals on to Gertassee. On a plateau behind the village, some 60 to 80 feet above high Nile, Cyrena fluminalis, Unio lithophagus?, and Paludina bulimoides † were found in abundance. The granitic rocks, reappearing about six miles below Gertassee, continue on both sides of the river, in the shape of high rugged ridges, to Debod, 18 miles south of Assuan, on the left bank, where there is an excavation or bay, from the granite not having protruded so high as in other situations; in consequence of this the sandstone overlies the latter. West of the village is observed a terrace-cliff, more or less covered with sand and shingle; it is traceable around the basin to where the river narrows again southwards. There, at various points, some 60 to 70 feet above the river's level, were found abundance of the three last-mentioned Shells. The desert has intruded greatly on the plateaus and alluvial banks; the latter rise in great heaps along the side of the old basin, so that it is now scarcely possible to define the limits of either. This is an interesting locality for several reasons. There stands the ruined temple, probably at least 2000 years old, on comparatively recent river-deposits, over which are strewed the tufaceous nodules so frequently noticed on the surface of these beds. In these banks the ancient race excavated their catacombs and caverns, whose ghastly remains are now spread at the entrances, and bleach on their sunny slopes; whilst a few feet higher is the above-mentioned plateau, with its immeasurably more ancient memorials spread over or in the now scanty soil, in the hollows and the crevices of the granitic rocks. 7. Ravines east of Philo, with Alluvium and Freshwater Shells.-From Debod the river runs between hills of granitic rocks, having high bands of alluvium on each side, to the top of the First Cataract. * Specimen No. 6. Specimens Nos. 10, 11, 12, + Specimens Nos. 7, 8, 9, Opposite Philæ are banks and heaps of river-deposit, some 30 feet higher than the modern limit of the inundation; eastward a fine broad valley opens out and stretches in that direction, curving gently northwards, when it sweeps round to join the river below Assuan, as will be noticed presently; its northern side, for some distance from the river, is formed of granitic eminences, with valleys which run northwards in divers windings to meet the former at Assuan. The above-mentioned valley is more or less covered with sand-drift and washings from the slopes on each side. A perpendicular section of 25 feet is well seen in the bank of a torrent-bed, about a mile from the river, on the southern side of the valley; and this shows the following succession: 1. River-alluvium overlain by sand-drift. 2. Stratified sand and gravel. 3. Conglomerate. 4. Coarse white sand." A similar section is perceived in another part of the valley to the north, showing much the same order of beds. The height of the first section may be from 35 to 40 feet above high Nile. Among the alluvial beds and ancient deposits in the ravines northwards, also strewing the surface where the rain had washed down the slopes, were abundance of Etheria semilunata, Iridina Nilotica, and Bulimus pullus, at heights varying from 40 to 60 feet above the level of the river. Nowhere in the Nile Valley is the vast force and fury of the storms that now and then burst on Nubia better attested than among the shattered rocks and ravines eastward of the First Cataract. I penetrated several miles in that direction, finding abundance of river-shells either among the soil in the hollows or strewn on the surface, impressing me strongly with a belief that the river had at one time forced its way through these ravines, just as it now makes its way through the others westward. The sandstone was again noticed between the pinnacles of granite, and even topping them in many places; whilst (as at Kalabshe) upturned masses lay along their flanks. These appearances led me to infer that, in all probability, these granite-rocks had been united at one time by sandstone, and that the river had washed away the intermediate and softer rock; moreover, that the sandstone, between the granitic projections in the present course of the stream, had given way to a greater extent, causing the river to sink to lower levels and thus abandon its ancient channels eastward. Is such a result likely to have taken place more readily during a general rise of the rivervalley? 8. Phila.-Opposite Phila, on the left bank, which is very steep, the remains of a terrace-cliff are definable, but so overwhelmed by drift as to render our endeavours to procure remains a failure. The monuments of Philæ show that, at least within the last 2200 years, the river has changed very little in any way. There is an opening *Specimens Nos. 13, 14, 15. in the western wall for entrance at high Nile; and there are many holes in its south-western angle for attaching boats at different levels of the water, all suited to the present rise and fall of the river. Midway in the easternmost channel, opposite Phile, we found a depth of 50 feet. That the river has subsided much since it flowed through its eastern channels is most probable; moreover, to account for the enormous sinking which has taken place, we can, according to what has been shown with reference to its ancient levels at and above the cataract, come to some such a conclusion as this-that the primæval Nile was a larger and more rapid river than the Nile is now. 9. Assuan and vicinity.-Proceeding down the river, terracecliffs are visible on the left bank. On one of these, nearly opposite Assuan, I found a few specimens of Cyrena; but I had not leisure to institute a careful inspection of the higher plateaus, some of which seemed fully 100 to 120 feet above the river. Proceeding eastward from Assuan, in a direction parallel to the valley opposite Philæ, I met with abundant proofs of ancient levels. Granitic ridges and boulders were observed interspersed among the old banks of alluvium in the ravine near the town; further east, a long ridge of sandstone runs northwards (with a white tomb at its extremity); from this point a vast valley runs north and south, marked by mounds of alluvium, being the continuation of the great valley opposite Philæ, which concentrates, with the other ravines, in one great plain, debouching on the river a little way below the town, as already stated. Abundance of river-shells strew the beds, and are met with along the banks, chiefly along the eastern side of the largest channel, as it sweeps round towards the river. Another excellent panorama of the Cataract may be seen from a Sheik's tomb on the top of a hill directly opposite Assuan. From the terrace-cliffs on the left bank to the eastern bank of the great ravine, the distance, in a straight line, may be about 2 miles. At After leaving Assuan the river-valley opens out; and along its right bank, at divers elevations, from 20 to 30 feet above the highest Nile, may be seen abundance of freshwater Oysters (Etheria semilunata)*, not only scattered in enormous quantities throughout the soil, but adhering in numbers to their old rocky bottoms. the village of Bahveech, opposite the Island of that name, I met with beds of these Shells among the old alluvium now being dug out of the crevices of the rock, besides Cyrena and Iridina, which were likewise plentiful. 10. Ombos and vicinity.-The temple of Ombos has been already mentioned (p. 10) with reference to the wearing away of its alluvial foundation and the change of the river's course within the historical period. Standing among the ruins and looking on the fine broad valley, we noticed numerous high beds and banks of soil dotting the surface. One in particular is well worthy of attention, being perhaps the greatest alluvial accumulation visible throughout the river's course from Wadi Halfeh to the sea; it runs along the left bank a short way below Ombos, at a place called Maneche, display*Specimen No. 16. ing a perpendicular section of stratified mud, which I ascertained by measurement to average between 80 and 90 feet in height. The lines of bedding are not always parallel, but, as the accompanying sketch (fig. 4) shows, are also oblique, which I conceive might result from the mud having been deposited by eddies and swirls. Fig. 4.-Diagram-section of an Alluvial Bank at Maneche, The surface is, as usual, covered with drifted sand and pebbles. I found no organic remains in this bed; but my examination was not sufficiently extensive to enable me to speak confidently on that point. Besides the above, I noticed, for the first and last time, on its southern flank, a great bed of stratified sand, red and variegated; throughout were interspersed rounded and oval masses of sandstone, of a black colour externally, becoming paler towards their centres, and varying in size from small oblong sticks to flat oval-shaped lumps several feet in length. In consistence this sand-bank appeared firm and indurated. Again, on the opposite bank, a mile below Ombos, we noticed quantities of a white substance, in the shape of roots of trees, interspersed throughout the alluvial deposit. The before-mentioned old mud-beds are in all probability the deposit of the river; but the variegated red sand and its nodules are very different from any formation that I have seen in the Valley of the Nile. From the general appearance of the surrounding country, it seemed to me an excellent locality for studying the earlier deposits of the river. No doubt between Assuan and Selsileh, where the country opens out, the early Nile had time to deposit the débris which it could not lay down in its narrow mountain-course above the First Cataract. 11. Selsileh and vicinity.—The white limestone of Thebes is seen for the first time on the right bank above Selsileh, but disappears before you reach the sandstone-gorge through which the river passes. This opening is made in a ridge of fine-grained sandstone crossing the valley almost due east and west. At the entrance to the river's channel, on each side, for some distance, are great banks and domeshaped hillocks of alluvium, evidently washed against the flanks of the ridge by the river in former times; as usual, these are covered with nodules of the concretionary tufaceous substance. On the right bank a great bed of alluvium has banked up what had evidently been an old river-channel, as the Shells found in the neighbourhood and other appearances indicate. Again, abundance of Cyrena were * Specimen No. 7, to contrast with the usual sedimentary deposit No. 8. † Specimen No. 9. See Specimen No. 10. VOL. XX.-PART I. c found on terrace-cliffs throughout the river's course, especially on the ridge on its left bank, some 80 to 90 feet above the most ancient of the temples and grottos, and, wherever any soil has been left, also strewing the surface of the loose sand. I noticed in the above situation several great rents and slips in the rocks, running N.E. and S.W.: these are rarely observed in the sandstone, unless in the neighbourhood of the granitic protrusions, none of which could, however, be seen, at least in the neighbourhood of the gorge. With reference to Sir Gardner Wilkinson's hypothesis, that the barrier at Selsileh dammed back the river and produced the rise recorded at Semneh, there can be but one opinion. When the locality has been even casually examined, it is evident that, supposing the height of the river to have been equal to that of the plateaus above-mentioned, its waters would not only flow through the large gorges right and left of the present entrance, but almost top the ridge altogether; moreover, granted even a barrier as high as the very summit of the ridge, then even the utmost effect on the rise of the river southwards could not have extended beyond a few miles. I believe a closer examination of the locality than I had an opportunity of making will afford more convincing proofs of the impossibility of any obstacle so far down affecting the rise of the river even at the First Cataract. After leaving Selsileh, terrace-cliffs are seen running along both banks to within a few miles of Edfu, and wherever the hills approach the river, until the limestone appears near Esneh, where the rivervalley opens out and all traces of high grounds are lost. III. Conclusion.-From the evidences adduced, it appears to me that there is reason to infer that the Nile in early ages was a rapid river; and that the force of the stream has been steadily declining, at least since the upheaval (?) of the valley ceased; therefore the wearing process has diminished: for this reason the bottom contains more mud, and in consequence may even be rising, on the whole; and this latter opinion Mr. Rhind seemed disposed to hold. His observations, however, tend to show that the change has been scarcely perceptible within the long historical period furnished by the records, excepting, as already shown, at certain points, caused by a change in the direction of the river's force: perhaps a similar change, or the giving way of a barrier close to Semneh, as Mr. Horner remarks*, might explain the fall of the river there. * "Observations on the Discovery, by Professor Lepsius, of sculptured marks on rocks in the Nile Valley in Nubia; indicating that, within the historical period, the river had flowed at a higher level than has been known in modern times," by Leonard Horner, Esq., F.R.S., &c. Edinburgh New Philosophical Journal for July 1850. See also Letters on Egypt,' &c., by Lepsius (Bohn, 1853, 12mo), pp. 30 and 238, and his reply to Mr. Horner's "Observations," p. 530. |