AprIL 8, 1897 ] 
ened TURE 
549 
The last report on the borings undertaken in the Delta of the 
Nile under the auspices of the Royal Society was communicated 
to the Society by the direction of the Delta Committee on 
November 12, 1885, and published in No. 240 of the Proceed- 
tzgs. This report dealt with the materials obtained from the 
three borings made at Kasr-el-Nil, at Kafr-ez-Zayat, and at 
Tantah, which reached depths of 45 feet, 84 feet, and 73 feet 
respectively. Although these borings made known to us the 
character of the delta deposits at greater depths than the 
explorations made by Mr. Leonard Horner and M. Linant de 
Bellefonds, yet none of them succeeded in reaching the solid 
rock on which these deposits lie, and in which the Nile Valley 
was originally excavated. It was therefore decided by the 
Delta Committee to make still more strenuous efforts to attain 
this result. 
In their attempts to carry out this important work, the Delta 
Committee have received the most valuable aid from the 
Secretary of State for War, the Inspector-General of Fortifica- 
tions, and the officers of the detachment of the Royal Engineers 
attached to the Army of Occupation in Egypt. 
Zagazig having been chosen as a suitable site for the next 
attempt to penetrate the delta deposits, a boring with a 5-inch 
tube was carried down to 97 feet, with a 4-inch tube to 190 feet 
6 inches, and with a 3-inch tube to 345 feet. 
From the surface to a depth of 115 feet the strata passed 
through in the Zagazig boring closely resembled: those already 
reported upon as occurring in the three earlier borings of Kasr- 
el-Nil, Kafr-ez-Zayat, and Tantah, and consisted of alternations 
of desert-sand and Nile-mud. 
At the depth of 115 feet a very noteworthy change was found 
to occur in the characters of the beds passed through, a mass of 
coarse sand and shingle being met with, and this continued to 
the depth of 151 feet. At the latter depth a band of yellow 
clay 2 feet thick was passed through, and under it sand and 
shingle beds prevailed till the lowest depth reached, 345 feet. 
In some of these shingle beds the fragments, which were usually 
well rounded—often, indeed, perfect pebbles—were very coarse, 
the fragments being of all sizes up to that of a hen’s egg. 
It is interesting to note that a boring made at Rosetta in the 
summer of 1885 by Mr. T. E. Cornish, C.M.G., Director of 
the Alexandria Waterworks, gave a section very similar to that 
at Zagazig. This boring was carried down bya 5-inch tube. 
Various beds of sand and mud, the latter containing in some 
places impure lignite, occurred down to the depth of 143 feet 
8 inches from the surface, but at this Jatter depth a mass of 
“coarse sand and pebbles* was found, which was followed 
down for about 1o feet. 
It will thus be seen that in the case of the Zagazig boring we 
find at the depth of 115 feet 8 inches (89 feet below sea level) a 
sudden change from the blown sand and alluvial mud of 
the Nile delta to masses of shingle and sand, and that the same 
change is found to take place at the Rosetta boring at a depth of 
143 feet 8 inches (134 feet 4 inches below sea level). That these 
shingle beds were deposited under totally different conditions 
to those which prevailed while the delta deposits were laid 
down, and that they were in fact the product of ordinary 
fluviatile action, can scarcely be doubted, and the determination 
of the geological age of the great gravelly deposit which is now 
shown to underlie the modern delta deposits, and to attain 
depths which certainly in places exceed 230 feet, becomes a 
problem of the greatest importance and interest. 
That the surface of these old gravelly deposits is a very 
uneven one is indicated by the difference of depth at which it is 
found at Rosetta and Yagazig respectively. It is possible, 
indeed, that this gravelly floor may in places rise through the 
whole of the Nile deposits, and form the present surface of the 
country. The late Sir Samuel Baker, in a letter addressed to 
the Delta Committee on February 20, 1886, called attention to 
the existence of the so-called *‘ turtle-backs,’’ which he regards 
as interesting proofs of ‘‘ the pre-existence of desert, before the 
Nile deposit had converted the lower level into delta.” 
In spite of the most careful search, not a single organism 
has been found which lived when the shingle beds were 
deposited, and which would serve to throw light on the geo- 
logical period to which they must be assigned. 
it was of considerable interest to determine the source of the 
various pebbles making up the deposit, which we may con- 
veniently speak of as the ‘‘Sub-delta formation,” I placed 
myself in communication with Dr. Karl von Zittel, of Munich, 
who possesses such a unique knowledge of the rocks and 
fossils of North-eastern Africa. In his obliging communica- 
NO. 143 2, VOL. 55] 
As, however, | 
tion, he has indicated the probable source of the pebbles which 
I forwarded to him, and writes as follows :— 
“‘The quartz and chalcedony pebbles, from depths of 120, 
160, 245, and 270 feet, are almost absolutely pure examples of 
those rocks. The sandstones (for example, those from the 
depth of 120 feet) rather recall, in their general appearance, the 
Tertiary Sandstone of Gebel Achmar, near Cairo, than the older 
(Cretaceous) Nubian Sandstone of Upper Egypt. The quartz 
and chalcedony pebbles, before referred to, might also be 
derived from the Gebel Achmar Sandstone. The absence of 
limestone pebbles is striking; it would appear that only the 
harder rocks have been preserved in the gravels of the Delta, the 
softer ones having been possibly worn away.” 
With respect to the igneous rocks found as pebbles in these 
shingle beds, Dr. von Zittel suggests, from their macroscopic 
appearance, that they may be derived “‘ from the side valleys of 
the Arabian Desert.” Of metamorphic rocks, quartzites, which 
are evidently altered sandstones, were found somewhat fre- 
quently. Many pebbles of sandstone, sometimes showing 
Stratification and fault-structures, but destitute of organic 
remains, were obtained at various depths. 
Pebbles of flinty limestone from various depths contain 
recognisable Foraminifera, and one is crowded with specimens 
recognised by von Zittel as ‘‘belonging to the Textularidz, 
Rotalidz, and Globigerinz.” Of these there are other specimens 
from a depth of 270 feet. Dr. von Zittel states :—‘‘ I hold it as 
probable that these pebbles come from the Eocene of the Nile 
valley. Flinty layers and concretions are extremely common in 
the Egyptian Eocene (as, for example, in Central and Upper 
Egypt). The absence of sections of Memmudites and Alveolna 
is particularly noticeable.” 
At the depth of 121 feet, a pebble of a somewhat different 
class of rock was obtained. This rock may have come from a 
Cretaceous deposit, and not from the Eocene, like the others. 
Of the general sources from which these pebbles were de- 
rived, Dr. von Zittel writes as follows :— 
“On the whole, it appears to me conceivable that these 
gravels under the delta originated at a time when the Nile had 
already formed its present valley, but not to so great a depth as 
at present. The majority of the rolled rock-fragments would 
seem not to have been derived from points extremely distant 
from those in which they are at present found.” 
There can scarcely be the smallest doubt that in this Sub- 
delta formation we have a series of deposits, which were formed 
under totally different conditions from those which prevail in 
North-eastern Africa at the present time. The land must have 
been at an elevation at least from 100 to 300 feet higher than 
at present ; and the Lower Nile, instead of forming an alluvial 
flat, asat present, must have deposited coarse sands and gravels. 
It is upon the very uneven surface of this Sub-delta deposit that 
the alluvial mud and sands of the delta have been deposited, 
as the surface gradually subsided below the level of the 
Mediterranean. 
The interesting problem of the geological age of this Sub- 
delta deposit remains to be solved, but it may be hoped that 
the explorations now being carried on by the Geological Survey 
of Egypt, under Captain H. G. Lyons, R.E., will furnish new 
and important evidence bearing on this important question. 
It is to be regretted that the borings carried out by the Royal 
Society have not set at rest the doubts which have long existed 
as to the depth at which the solid rock-floor lies below the 
surface of the delta. But while this has not yet been accom- 
plished, it is satisfactory to have been able to show that the 
supposed’ insignificant thickness of the alluvial deposits is 
altogether a mistake ; while the existence of an underlying 
formation, laid down under conditions totally different to those 
which prevail at present, has been demonstrated. . i 
Communications have lately passed between the English War 
Department, the Egyptian Public Works Department, and the 
Royal Society, which lead us to hope that borings, to be shortly 
undertaken for economic purposes, may, either with or without 
aid from this Society, supply the means of reaching greater 
depths than that obtained at Zagazig, and possibly of reaching 
the old floor of solid rocks on which the Sub-delta deposits 
rest. : 
Geological Society, March 24.—Dr. Henry Hicks, BERS 
President, in the chair.—The following communications were 
read :—Notes on some volcanic and other rocks which occur 
near the Baluchistan-Afghan Frontier, between Chaman and 
Persia, by Lieut.-General C. A. McMahon and Captain A. H. 
McMahon. In the first part of this paper Captain McMahon 
