me in the east the almost horizontal lines of cliffs forming the most
westerly point of the mysterious plateaux of Erdi. The word “Erdi” means
in the language of the Toubous “expedition, razzia,” and would appear to
have been applied to that region from time immemorial because it served
as a meeting-place for the bands of raiders who put the caravans to
ransom and pushed their raids as far as northern Dar Four and Kordofan,
and sometimes even to the valley of the Nile in its middle reaches.
According to the guide, rocky tablelands were to be found there, of an
altitude comparable with that of Ennedi; the rains were less rare than
in Borkou, the grazing-grounds for camels abundant, and the points where
water could be found were hidden away in gorges difficult of access,
little known, and hard to find the way to. For his own part, he hardly
knew any except those of Erdi-Dji and Erdi-Ma, separated by a distance
of 70 or 80 miles.
I hesitated some time before continuing my journey towards this region,
whose very name was unknown till now; my water-barrels only gave me a
reserve of some thirty gallons, and my men’s skin bottles were so
corroded by the salts of sodium they had transported that they were
empty after twenty-four or thirty-six hours’ march. My camels, thin,
worn out, and more and more mangy, could not do more than 20 miles a
day, and I only had at my disposal ten days’ supplies for my detachment,
so that any error on my guide’s part might put me into a critical
position.
_Erdi._—In spite of everything I resolved to make the attempt, trusting
in fortune to ensure its success. In two marches we succeeded in
reaching the foot of the cliffs of Erdi-Dji, 750 feet high and about
2000 feet above the sea. We found there good grazing for the camels, and
from that day onward we had abundant fodder at each successive stage, so
that I was delivered from the dread of seeing my indispensable beasts of
burden waste away from inanition. The water was no less abundant, and
was found in natural cisterns hollowed out by waterfalls in the beds of
dried-up torrents that came down from the plateau. Some of these
cisterns contained nothing but sand; but it was enough to bore a hole 1
or 2 feet deep in the sand to obtain a sufficient store of water.
From the top of the cliffs all that could be seen was an immense
plateau, slightly undulating, and rising gradually towards the north-
east. Beyond the line of the horizon some dozen miles away, there rose,
as our guide told me, other cliffs; but all I could do was to take note
of that information without being able to verify it.
Continuing our route eastwards along the foot of the cliffs, we reached
five days later the region of Erdi-Ma, decidedly higher than that of
Erdi-Dji: the highest altitude I had the opportunity of measuring
exceeded 3000 feet. Our bivouac was installed at the entrance of the
gorges of Dourdouro, where very picturesque natural cisterns are to be
found containing abundant quantities of water withdrawn by the positions
of the enclosing rocks from the drying action of sun and wind. During
the whole of the way thither we did not see a living soul, any more than
in the neighbourhood of Dourdouro.
My guide never having gone beyond that point, it was impossible to push
my investigations further. Besides, I had now only four days’ supplies
left, a fact which obliged me to change my direction and make for Wad
Mourdi, on the northern border of Ennedi, where I was to receive fresh
supplies. I had eventually to be satisfied with determining the position
of this point and measuring a few heights while we were renewing our
store of water before starting again after a day’s rest.
This expedition, though limited to the south-western border of the
massif of Erdi, revealed some interesting facts about the configuration
of the country towards the 18th degree of latitude north and the 23rd
degree of longitude east of Greenwich; the altitudes increased from west
to east, and it seemed likely that the massif of Erdi was connected in
one direction with the mountains of Tibesti by the plateau of Jef-Jef,
and in another with the still unknown massif of El Aouinat, situated
approximately between the 22nd and 23rd degrees of latitude north and
the 24th and 25th degrees of longitude east.
Later information gave me a few further indications about western Erdi,
where two water-points were found; one Bini-Erdi, about 80 miles north-
east of Dourdouro, and the other, Erdi-Fouchini, some 60 miles north of
Dourdouro, at the foot of a line of tall cliffs. The deduction may be
allowed, for the time being, that the central tableland of Erdi offers
altitudes presumably superior to 4000 feet, and that it slopes gently
down on the east to the great sandy plain, without vegetation or water,
across which passes the route from El Aouinat to Merga, a route that
establishes direct but very difficult communication between Koufra and
Dar Four, to the east of the 24th degree of longitude.
_Between Erdi and Ennedi._—In leaving Dourdouro to march southwards I
was going into the unknown. I could, no doubt, see in front of me, 40
miles away, the crests of northern Ennedi, at the foot of which I was to
find the water-points of Aga and Diona; but to seek the said points
without guide in the chaos of rocks was a risky undertaking, and might
have been held unreasonable if the way our supplies were running short
had not obliged me to go forward.
A vast depression, stretching from south-south-west to north-north-east
and of an average breadth of some 30 miles, separated Erdi from Ennedi;
it was the depression I heard spoken of earlier as a prolongation of
that of the Bahr El Ghazal, through which Lake Chad once poured its
waters into the lakes of Toro and Djourab, and consequently that by
which the basins of the Chad and the Nile might in ancient times have
entered into communication. That being so, I took the utmost care in
examining the region and determining the altitudes. The lowest point was
found about 30 kilometres from Dourdouro. Its altitude was 1750 feet, or
1000 feet higher than that of Bokalia at the north-eastern extremity of
the Djourab. The slope was therefore from north-east to south-west, as
was confirmed by the shape of the ground and the general direction of
the valleys running into that depression, and I was able to conclude
that if an ancient river once flowed in the bottom of that broad valley,
which is hardly likely, it ran, not towards the Nile, but towards the
lowlands of the Chad. By this evidence, one of the most important items
of my geographical programme was fully elucidated: the basin of Lake
Chad constitutes in the centre of Africa a closed basin which has never
been connected with the basin of the Nile. The lake zone, now dried up,
consisting of Kanem, the lowlands of Lake Chad, and Borkou, was once the
outlet for the affluents of Lake Chad and for many great rivers coming
down from the mountain mass of Ennedi, Erdi, and Tibesti. Its outline at
successive periods—an outline in all probability very irregular—might be
indicated by the hypsometric curves 270—260—250 metres, adopting for the
Lake Chad of to-day the altitude of 240 metres. Its extent at that
period must have been comparable with that of the Caspian Sea at the
present day, and its greatest depth some hundred metres.
In the evening of the second day’s march, when we were drawing near the
foothills of Ennedi, we had not yet found any well, and our tiny store
of water was used up. But spying in the west a notable gap in the line
of hills, I thought we should be likely to find a water-point there, and
profited by the coolness of the night to try to reach it. At dawn we
came out on a fine river, dried up, where we got a little water by
digging holes in the sand. By good luck our guide, Sougou, recognized
that we had reached Oued Mourdi, where he had come by another route some
six months earlier; thanks to which discovery, after a little search we
were able to bivouac beside the well of Diona.
If I had had time and means, it would have been extremely interesting to
explore up to its starting-point the great depression I had just
crossed, a depression which perhaps comes down from the region of Merga
in the heart of the Libyan Desert, where the natives agree in declaring
that there exists a little lake surrounded by a palm plantation. The
probable position of Merga is between the 25th and 26th degrees of
longitude east and 18th and 19th degrees of latitude north. This oasis
is situated on the direct route from Ennedi to Dongola, about 200 miles
from the last water-point of Ennedi (Gourgouro).
[Illustration: FRENCH SUDAN
Map to illustrate the WORK OF THE MISSION TILHO in TIBESTI, BORKU, ERDI
AND ENNEDI
THE GEOGRAPHICAL JOURNAL, AUG 1920.
_Modified Polyconic (1/M. International Map) Projection._
_Published by the Royal Geographical Society._
TIBESTI Tilho]
=6. Exploration of Ennedi.=
Having reached the well of Diona on 11 November 1914 in the morning, I
was joined next day by the camel-corps section of Borkou and Ennedi,
which brought me fresh supplies and were charged with the mission of
getting into touch with the nomads of eastern and central Ennedi, who
refused to acknowledge our authority and committed acts of brigandage on
our lines of communication. A few patrols in the neighbourhood having
made it clear that the rebels had decamped before us and taken refuge on
the high plateaux, the camel corps under the command of Captain
Châteauvieux climbed the heights of Erdébé, where they began an active
pursuit of the rebels. At the same time I reconnoitred the water-point
of Aga, 30 miles further east on the route from Erdi to Dar Four, a
route followed at that period by a certain number of Senoussist
emissaries on their way to exhort the Sultan Ali-Dinar to join in the
Holy War! For it will be remembered that Turkey had just at that date
entered into the war against us, and that the plan of the German general
staff included a vast Musulman rising destined to drive the French and
British out of their African possessions.
_Eastern Ennedi._—Finding no traces of the rebels at Aga, I rejoined the
camel corps in their occupation of the cisterns of Keïta on the plateau
of Erdébé, and until the end of November our reconnoitring columns
explored the labyrinth of gorges and rocky valleys over which the
refractory natives had scattered, without offering serious resistance
anywhere. The cold was beginning to be rather unpleasant, especially
when the north-east wind blew, but the thermometer did not fall as low
as zero. The water-points were extremely numerous, a fact which favoured
the break-up into small fractions of the rebel bands, whose chief
anxiety appeared to be the getting of their herds of camels and oxen and
their flocks of goats into a safe place. They did not seem to worry much
about their women and children, and let us capture them with the
serenest unconcern, being well aware that we should do them no harm, and
that their sustenance would be assured for the time being by our black
troops, always glad to leave the preparation of the daily cousscouss to
the other sex. To conclude this series of operations we had to fix the
limits of eastern Ennedi. An expedition was sent to Bao, 60 miles
southwards, the last water-point in the region, and thence to Kapterko
in the south-east, where a few rebels were captured. Another expedition
fixed the position of the well of Koïnaména some 50 miles east, and went
a stage further, to the beginning of the great plain without water or
vegetation that stretches out of sight to the eastward.
The general physiognomy of the country was that of a rocky tableland
intersected by a great number of valleys, more or less deep, and gorges,
separated by many little jagged chains of sandstone running in all
directions, and varying in height between about 200 and 500 feet. All
those depressions are covered with grass and shrubs, affording excellent
pasturage for the hillman’s flocks. Of plants useful for human food we
found gramineæ such as the Kreb and Anselik; what is more, the soil of
the valleys was literally covered in places with water-melons and
colocynths. Though I found no traces of tillage anywhere, I even had the
surprise of noticing from time to time hardy stalks of the wild cotton
plant, some reaching 6 feet in height.
Almost every year at the end of the rainy season temporary rivers flow
through these depressions, some of them turning northwards (and
consequently tributaries of the Chad basin), the others southwards,
where they once used to feed some great tributary of the Nile basin.
Numerous pools formed during the rains hold out for a longer or shorter
time in the flats of the more considerable of these valleys, while in
the narrower parts the water is stored in natural reservoirs, more or
less hard to get at, hollowed in the sandstone by the falling waters as
each torrent makes its way down from one ledge to the next.
The greatest altitude I noticed in the course of my surveys on the
plateaux of Erdébé was found in the water-parting between the slope
towards the Chad and the slope towards the Nile: it was of 3600 feet.
The highest summits in the neighbourhood rising only from 250 to 400
feet above the general level of the country, it may be estimated that
the chief altitudes of that region vary between 4000 and 4200 feet.
Twenty miles east of Koïnaména, in the transition zone between the
mountains and the plains, the altitudes of the bottom of the valley was
still superior to 3000 feet. It is possible, moreover, that 40 miles
away to the north-east certain summits of the water-parting rise to 5000
feet.
The natives who live a nomadic life on the plateaux of Erdébé amount in
number to several hundred families. Their settlement, meagre in the
extreme, usually consists of a few pieces of matting stretched on stakes
in a corner of a ravine, round a thorn enclosure in which their flock of
sheep and goats is shut up; at the slightest alarm men and beasts
stampede among the rocks. If I had to seek in the animal kingdom a term
of comparison for these tribes, I think I should choose their fellow-
denizen the jackal: they possess its cunning, its audacity, its
cowardice, its mischievousness, its endurance, its speed, and its
predatory instincts.
The only other wild animals we saw were gazelles, antelopes, and
ostriches; it is reported that as long as the above-mentioned pools
remain, boars, panthers, and lions may be found, but we had no
opportunity of testing the truth of this assertion.
On December 9, in the afternoon, having made preparations for our
departure next morning, we set free our prisoners, imposing no
conditions beyond that of telling their fellows our desire to see peace
and quiet reign throughout the country. “Let the nomads devote
themselves to the raising of their flocks and to trading in salt and
millet,” I said; “let them give up raiding the peaceful tribes of the
Sudan and the Nile, and the caravans that cross the desert, and I will
leave them at liberty in their mountains.” Whereupon an old woman
answered me, “We will carry your words faithfully to our husbands and
sons, and we will bid them come and submit to your authority; we are all
weary of our perpetual insecurity; we desire peace and justice. You have
treated us well, you have given us millet and meat; we have eaten all we
wanted to eat, and now we know that you are strong and generous. Allah
reward you!”
Alas! my reward was that for two years longer these inveterate brigands
did not cease raiding in every direction, and that the camel corps had a
particularly difficult task in guarding convoys and putting down
pillaging.
_Western Ennedi._—It only remained to me to cross the central part of
Ennedi in order to have a clear outline of the general physiognomy of
the country, thanks to the aid of surveys previously executed on its
western borders by several officers who had taken part in military
operations in Western Ennedi under the orders of Major Hilaire and Major
Colonna de Léca. With this end in view, I marched in the direction of
the military post of Fada by Boro and Archeï.
For a week our route lay through a maze of sandstone rocks where no
track existed, and through which our guides zigzagged from crest to
crest with remarkable sureness. Sometimes we made a long _détour_ to
cross a wadi near its source; sometimes we marched straight for the
obstacle, dropping down steep ledges that inspired little confidence in
our animals, or crossing difficult ridges that the camels could only
climb after being unloaded. Everywhere were narrow gorges and jagged
crests, with here and there a few leagues of easy going in the
neighbourhood of the temporary pools that usually marked the convergence
of certain important ravines.
In this uneven ground with its narrow horizons one pasture-ground
succeeded another, but we saw no trace of inhabitants. And yet water was
not wanting, whether in natural cisterns or in great pools like that of
Kossom Yasko. We skirted on the south the tableland of Basso, higher,
according to our guides, and harder to climb than that of Erdébé, but,
so far as I could judge at a guess, its height is not likely to be as
much as 5000 feet.
We took a day’s rest in the excellent pastures of Boro before leaving
the central plateau of Ennedi to drop down to the next level, 400 or 500
feet below. Then our way lay along a fine river of white sand, between
banks 60 or 80 yards high, where the traces of the last flow of water
could be seen 6 or 7 feet up the bank. The coming of the floods is so
sudden, and the banks so steep and smooth, that it is dangerous to take
that road in the rainy season. No winter passes without some heedless
wayfarers being surprised and carried away by the rushing torrent that
comes sweeping down the valley with the speed of a galloping horse.
After this splendid sand-road came a stretch of rocky going, followed by
a zone of waterfalls we had to get round by a march on the plateau. The
lower we got the more picturesque the landscape became; the cliffs,
gaining in height what we lost in altitude, grew more and more imposing,
the crests more jagged, the ridges more often broken by gaps. Isolated
peaks appeared here and there, whose pure outlines and bold summits put
climbing out of the question. On all sides there rose in the distance
rocks, some broad, some slender, but all of the same height and grouped
irregularly, so that sometimes, when very close together, they looked
like groups of men.
On the 17th of December we reached the foot of the last ledges, on the
western borders of Ennedi, at the altitude of about 1800 feet—that is to
say, about that of the depression separating Erdi from the plateaux of
Erdebe—and pitched our tents in the valley of Archeï, the most
picturesque of the beautiful valleys of the Ennedi. The century-long
erosion of wind and water, carving the great sandstone masses that line
the valley, lavished throughout the landscape the most admirable effects
of natural architecture. The approaches of the great grotto, above all,
and of the sheet of water teeming with little fish, were a pure delight
for the eyes: the sheer cliffs, fretted into colonnades crowned with
turrets and belfries, were burnt to tones of faded ochre that made the
blue of the sky seem deeper and more luminous still.
[Illustration: MOURDIA WOMEN AND CHILDREN, PLATEAU OF ERDÉBÉ (1000 m.),
ENNEDI]
[Illustration: THE FORT OF FADA, ENNEDI]
[Illustration: CAVES OF ARCHEÏ, ENNEDI]
From this exploration it became apparent that Ennedi is, roughly
speaking, a triangle covering about 12,000 square miles (30,000 square
kilometres). It consists of a succession of sandstone plateaux rising in
tiers from the base level of 1600 feet to that of 4300 and possibly even
4800 or 5000 feet in the parts of the country which had to be left out
of our investigations (Basso and eastern Erdébé). It falls by steep
slopes to the plains of the Libyan desert. The plateaux of Ennedi are
ravined by many valleys, most of them very deep, whose waters only flow
for a few days or weeks each year after the rains (August and
September). These waters hurl themselves from ledge to ledge in
waterfalls, hollowing out at the foot of each fall natural cisterns in
the rock, where the water remains a longer or shorter time according as
it is well or ill sheltered from the torrent beds. The roads usually
follow the torrent beds, except when blocked by masses of crumbled rock,
in which case a more or less awkward circuit has to be made. At the
points where the main valleys converge great muddy ponds are usually
formed, but they are shallow and short-lived. In all the valleys
splendid grazing-land is found, where not only camels but also thousands
of oxen could live if the problem of drinking-troughs did not present
itself every year in the height of the dry season. For at that moment
the natural cisterns that have still kept some store of water are grown
few in number, and are nearly always very hard to get at. Most of the
great temporary pools are dry, and subterranean water is no longer found
except in the great wadis, where the wells (that have to be dug out
afresh every year) go as deep as 20 or 25 yards.
The inhabitants of Ennedi, nomads or semi-nomads, are very poor; the
chief tribes are the Bideyats (or Annas), the Gaedas, and the Mourdias,
which all together represent hardly more than 2000 souls. But they are
by tradition so addicted to brigandage and so untamable that as large a
troop of police is needed to keep them in hand as for a population of
40,000 in the settled regions.
Ennedi has no vegetable food resources; there are neither palm
plantations, nor native gardens, nor millet fields. And yet the soil is
more fertile than in Borkou and the periods of drought shorter. The
chief agricultural interest of the region lies in its excellent pasture,
where the camels find abundant provender of very good quality.
_In Mortcha._—From Archei I went to the post of Fada, 40 miles or so to
the north-west, for a few days’ rest, after which I undertook a new
series of reconnaissances westwards, for the purpose of exploring the
still imperfectly known desert regions of northern Mortcha, too often
visited by the raids of the refractory tribes. I was thus enabled during
the early days of January 1915 to trace the course of the temporary
rivers that receive the waters from the western slopes of Ennedi. For a
few days every year these rivers roll down a volume of water sufficient
to stop the march of caravans and convoys for a longer or shorter time,
and continue their course for 200 or 300 kilometres before each of them
reaches the pool in which it ends. As they have not force enough to go
further, all one finds beyond the terminal pool is a valley-way more or
less clearly marked, and blocked with sand from place to place, but
still visible for fairly long distances. It has been concluded that they
formerly ran into the ancient lake of Djourab, the level of which is
from 200 to 300 yards lower. The most interesting of these rivers from
the geographical point of view is the wadi Soala, which in the central
and lower parts of its course separates the granitic zone of Mortcha
from the sandstone of Ennedi.
The whole region is one succession of good grazing-grounds for camels,
but which can be made use of only a few months a year while there is
water in the temporary pools. The one that lasts longest, that of
Elléla, in which the wadi Oum-Hadjar comes to an end, is not entirely
dry till April or May when the annual rains have been normal, in which
case it makes direct communication possible between Borkou and Wadaï.
_Between Ennedi and Borkou._—I next set out northwards from Ennedi in
the direction of Madadi and Wadi-Doum, which had been adopted for the
time being as their headquarters by some rebel bands from Tibesti, which
attacked indifferently the caravans from Wadaï going to Arouelli for
salt and our unescorted convoys of supplies circulating between the
posts of Faya, Fada, and Ounianga. At the moment when I arrived in the
neighbourhood they had just carried out successfully several of these
surprise attacks, and were making off to their mountains to get their
booty into a safe place. Unable to go after them, for my camels,
exhausted by three months’ reconnoitring and hard fare, could not
challenge those of the rebels for speed, I decided to return without
delay to Faya to organize reprisals.