9. Additions to Geographical Knowledge Resulting from the Expedition
Jalo.—The first portion of Hassanein Bey’s route from Jaghbub to Jalo appears to be identical with that trodden by Rohlfs in 1869. At Gara Matan Sidi, about half-way between Jaghbub and Jalo, the track forks and Hassanein Bey went by the northern (Zawaiya) branch, which passes Hiseila Wells and enters Jalo from a more northerly direction than the southern (Majabra) branch taken by Rohlfs.
Hassanein Bey’s position for Jalo is almost identical with that of Rohlfs, but peculiar interest attaches to the former’s determination of its level at sixty-one meters above sea. Rohlfs, visiting the place in 1869 and 1879, had found the aneroid to indicate a level below the sea in 1869, and above it in 1879, and had ultimately concluded that both Aujila and Jalo lay about at sea-level.[4] Hassanein Bey’s determination is based on ten days’ aneroid readings and comparison with Siwa, and it is noteworthy that exactly the same altitude (sixty-one meters) for Jalo results whether the comparison is made with the readings of the standard barometer in the meteorological station at Siwa during the same period, or with the readings taken by Hassanein Bey with the same aneroid on four days at Siwa two months earlier (allowance being made, of course, for the annual variation of pressure over the intervening period). There can, I think, be hardly any doubt of the greater accuracy of Hassanein Bey’s determination, since it is unlikely that Rohlfs’s readings extended over so long a period, and it is practically certain that no comparisons were made by him with simultaneous observations at a place of known level. It should however be mentioned that Hassanein Bey’s level probably refers to a somewhat higher observation point than that of Rohlfs; for owing to sand-drifts enveloping the houses, the inhabitants of El Erg are gradually rebuilding their dwellings on higher ground, and his observations were taken in one of the most recently constructed of these. Another point worthy of remark is that although Hassanein Bey’s determination is to a certain extent checked by the exact agreement of the two methods of comparison above referred to, the day-to-day variations of pressure observed at Jalo are much in excess of those at Siwa during the same ten-day period. The extreme range shown by the aneroid at Jalo was 10 mm. against 5 mm. of the standard barometer at Siwa, and the 7 mm. average difference of pressure between the two places for the ten days of comparison, which has been used to calculate the new value of the level, is the mean of difference ranging from 1 to 12 mm. on different days. The relatively great variability of atmospheric pressure at Jalo, which readily explains the discordant results noted by Rohlfs on different dates, may be closely connected with the sand-storms which are so frequent in the neighborhood.
Bir Buttafal.—Bir Buttafal (“Battifal” of Rohlfs) is of importance as being the last watering-place for caravans proceeding on the weary desert march of nearly 400 km. to Zieghen. The position found for Bir Buttafal by Hassanein Bey agrees fairly well with that given by Rohlfs:[5]
| Lat. N. | Long. E. | Meters above sea | |||||||
|---|---|---|---|---|---|---|---|---|---|
| ° | ′ | ″ | ° | ′ | ″ | ||||
| Bir Buttafal, Hassanein Bey | 28 | 54 | 26 | 21 | 45 | 15 | 98 | ||
| Bir Buttafal, Rohlfs | 28 | 56 | 22 | 21 | 44 | 10 | 58 | ||
| Difference | 1 | 56 | 1 | 5 | 40 | ||||
Zieghen (“Sirhen” of Rohlfs).—Zieghen is the name of a district containing numerous wells. It is not inhabited, but is of great importance as lying on the main caravan route from Jalo to Kufra. The principal well used by the caravans is El Harrash. Rohlfs did not visit Zieghen; he traveled from Jalo to Kufra by the more westerly track through Taiserbo and Buseima, and the position shown for Zieghen on his map, which was based merely on his guides’ statements, is about 100 km. too far to the east-northeast.
As the journey from Jalo to Kufra by any future traveler is likely to be undertaken in the winter, when the question of fuel is second only to that of water, it is worth noting that the first hatab (fire-wood) is met with at about 342 km. after leaving Bir Buttafal, and 52 before reaching El Harrash Well. In an emergency water may be got at Matan Abu Hosh, the old well of Zieghen, about 18 km. before reaching El Harrash; but El Harrash yields better water, and being the regular halting-place of the caravans, the water can usually be obtained there without digging; hence, unless the caravans are very thirsty they usually prefer to go on to El Harrash rather than make a halt at the old well. Excellent water can be got anywhere in the neighborhood of El Harrash by digging to a depth of three or four feet. From El Harrash to Buseima is about 54 km. in a direction a little west of south, and from El Harrash to Taj, the principal town of Kufra proper, is 182 km. in a southwesterly direction.
Taiserbo.—Taiserbo, the most northwesterly oasis of the Kufra group, has not, so far as is known, been visited by any traveler since Rohlfs’s day. Its position was however indicated to Hassanein Bey as lying between 70° and 80° west of north from El Harrash, at a distance of 60 to 70 km. This indication would place Taiserbo very nearly in the position which Rohlfs assigned to it. Rohlfs’s position for his camp at Kasr Djrangedi is probably therefore substantially correct, though it is likely that the oasis is in reality less extensive than shown on his map.
Buseima.—Although Buseima was not visited by Hassanein Bey on this occasion, his fixation of the position of El Harrash, in combination with his former rough compass-traverse from that place to Buseima with Mrs. Forbes in 1921, permits of a fair approximation for its position. Hassanein Bey’s estimates of distances and bearings on his former journey (adjusted by his recently observed latitudes at El Harrash and Taj) give his camp in Buseima as being 60 km. from El Harrash in a direction of 5° east of true south, and from his camp to that of Rohlfs (Ain El Nusrani) was roughly about 15 km. in a true west-northwesterly direction. Adopting Hassanein Bey’s recently fixed position for El Harrash, this would give a position for Rohlfs’s camp about 30 km. southwest by south of where Rohlfs placed it, as is shown by the following comparison:
| Lat. N. | Long. E. | ||||||
|---|---|---|---|---|---|---|---|
| ° | ′ | ″ | ° | ′ | ″ | ||
| Buseima (Rohlfs’s camp) from Stecker’sobservations | 25 | 11 | 42 | 22 | 15 | 0 | |
| Buseima (Rohlfs’s camp) from HassaneinBey’s estimation | 24 | 38 | 11 | 22 | 5 | 46 | |
| Difference | 13 | 31 | 9 | 14 | |||
It would hardly seem possible that Hassanein Bey can have made so large an error as 25 km. in his former estimation of the distance of Buseima from El Harrash, and hence it would appear reasonable to think that there was some error either in Stecker’s observation or (what is more likely) in his reduction of it. This point is referred to further on in the discussion of the position of Boema ([p. 334]).
Kufra (Kebabo of Rohlfs).—The name “Kufra” is now generally applied, not to the whole of the Kufra group of oases as was done by Rohlfs in 1879, but specially to the area called Kebabo by that traveler.
The seat of local government and principal settlement is the walled town of Taj, situated on a rocky cliff overlooking the depression of the oasis proper which lies to the south and contains the villages of Jof, Buma, Boema, El Zurruk, Talalib, and Tollab. Hassanein Bey carried out latitude observations at Taj, and proceeded 3 km., on a bearing of 16° west of south, to Jof, from which place he made very careful estimations of the distances and bearings of the other villages of the oasis, which has enabled their relative positions to be plotted on the map with much closer approximation than had hitherto been possible.
Considerable interest attaches to the position of Boema, the easternmost village of Kufra, for it was here that Stecker camped with Rohlfs and made his observations for latitude and longitude in 1879. Hassanein Bey found Boema to lie 2 km. from Taj, in a direction 54° east of true south. Accepting his determination of the position of Taj, this leads to the following position for Boema as compared with that given by Rohlfs:
| Lat. N. | Long. E. | ||||||
|---|---|---|---|---|---|---|---|
| ° | ′ | ″ | ° | ′ | ″ | ||
| Boema, according to Hassanein Bey | 24 | 13 | 8 | 23 | 24 | 40 | |
| “ “ Rohlfs[6] | 24 | 31 | 38 | 23 | 12 | 40 | |
| Difference | 18 | 30 | 12 | 0 | |||
Hassanein Bey thus places Boema some 40 km. south-southeast of the position assigned to it by Rohlfs from Stecker’s observations. The remarkable thing about this large discrepancy is that it is chiefly in the latitude, which was directly observed by Stecker at Boema itself, and by Hassanein Bey at Taj, only 2 km. away from Boema. I have not been able to find any details of Stecker’s observations, except that they were carried out with a “prismatic circle.” But I have subjected the original records of Hassanein Bey’s observations for time and latitude at Taj to very careful examination, and there is overwhelming evidence that his latitude for that place cannot be in error by more than 1′. He observed the altitude of Polaris at Taj on no fewer than six different nights, with a watch whose error on local time was accurately known from sun and star observations carried out on the same dates. From the internal evidence of the observations themselves, the watch-error at the time of sighting Polaris cannot on any occasion have been uncertain by more than two seconds, which would not, of course, sensibly affect the latitude found; the recorded magnetic bearing of the star sighted, as well as its rate of apparent motion, proves that the star used for latitude in each case was really Polaris; and the greatest difference of any single observed latitude from the mean of the six nights’ observations was only 15″, the average departure of a single observation from the mean being 12″. Hassanein Bey’s latitude of 24° 13′ 47″ for Taj can therefore be unhesitatingly accepted as correct within 1′; and since there is not room for an error of even this amount in his estimation of the short distance of Boema from Taj, it becomes absolutely certain that Rohlfs’s latitude for Boema is over a quarter of a degree too high.
It is curious to notice that in the case of Buseima ([p. 332]) the discrepancy of 13′ 31″ between Rohlfs’s latitude and that estimated from Hassanein Bey’s recent work is of the same order and of the same sign as that found at Boema; and that a negative correction equal in amount to the sun’s semidiameter would in each case bring the results of the two observers into fairly close agreement. The explanation hence suggests itself that Stecker may have determined his latitudes by observation of the upper limb of the sun at noon, and both at Buseima and Boema failed to correct the measured altitude for the semidiameter, thus making both latitudes 16′ too great. A mistake of this kind, as every scientific traveler knows, is very easily made in hurried reductions in the field; and at the time when Stecker carried out his observations and calculations in Kufra, both he and his brave leader were in imminent peril of losing their lives at the hands of treacherous Badawi.
A similar explanation may account to a large extent for the discrepancies of longitude at the two places. Thus, according to Hassanein Bey’s work, Rohlfs’s longitude for his camp at Buseima is 9′ too far east, and that for his camp at Boema 12′ too far west. We have only to assume that Stecker observed the sun’s lower limb in the morning at Buseima, and the upper limb in the afternoon at Boema, for finding the local times, and in each case omitted to correct the observed altitude for semidiameter, to account pretty completely for both discrepancies of longitude.
The puzzling thing about the above explanation of the errors of Rohlfs’s map is that Rohlfs actually traveled the distance between Buseima and Boema, and estimated it at 120 km.,[7] whereas Hassanein Bey’s positions would indicate that the true distance is 40 km. greater. But as Rohlfs’s statement of the distance was obviously written after Stecker had determined the positions of the places astronomically, it is probable that he obtained his 120 km. by calculation from the astronomical positions, rejecting any rough estimate he may have made of the distance from his times of marching. Both Hassanein Bey and Mrs. Forbes had considered that the true distance was much greater than 120 km. when they traversed it in 1921; but as on that occasion no observations for position were taken, it remained uncertain whether either Buseima or Boema had been wrongly placed on Rohlfs’s map. It is now practically certain that both were wrong.
As regards the level of Kufra, it is satisfactory to notice a very close agreement of Hassanein Bey’s observations with those of Rohlfs. Hassanein Bey’s barometer-readings at Ezeila, to the south of Jof, give 389 meters for the level of that place, and he estimates that Boema lies some ten meters higher; this would give about four hundred meters for the altitude of Boema, a figure identical with that found by Rohlfs. Taj, which has been built on the cliff north of Jof, since Rohlfs’s day, is found to be 475 meters above sea-level from a series of aneroid-readings extending over a fortnight. The outlying villages of Kufra which lie north of Taj are lower than Taj itself, but substantially higher than the southern villages of Kufra; Awadel is 434 meters above sea, and Hawari and Hawawiri are about the same altitude.
There is also fairly close agreement as to the extent of Kufra from north to south. Rohlfs’s map makes the extent in altitude between Hawawiri and Tollab to be about 35 km., while Hassanein Bey makes it 30 km. But when we come to the distance over which the villages extend from east to west, there is a much graver discrepancy. Rohlfs makes the extent from east to west (Buma to Tollab) about 40 km., while according to the latest estimations by Hassanein Bey the true extent is only about 21 km. As Rohlfs appears to have located many of the villages on his map merely from Arab statements, and not from careful personal estimation as did Hassanein Bey, we need have no hesitation in accepting the latter’s relative positions as by far the more nearly correct, and hence concluding that Rohlfs’s map gives an east and west extension which is nearly double the truth.
The error in east and west extension (so far as concerns the placing of the villages, not the extent of the vegetation) is even greater on the map prepared by me and published by Mrs. Forbes in 1921.[8] This is due to the distance between Jof and Tollab having been much overestimated on the former journey; it was given to me as about 42 km., while according to Hassanein Bey’s latest estimation it is only 20 km.
A matter which will at once strike the eye of any one who compares Hassanein Bey’s latest map of the Kufra villages with that published by Mrs. Forbes is that in the later map a place called Ezeila is shown south of Jof, while in the earlier map (which was prepared from Hassanein Bey’s own data and rough sketches) Ezeila is shown north of Hawawiri. The explanation is that there are two Ezeilas. The name “Ezeila” is applied locally to any outlying well (usually with a clump of palms) which forms the last watering place for caravans leaving the oasis. Thus the northern Ezeila is the last well for a traveler leaving Kufra to go northeastward toward Jaghbub, while the southern Ezeila is the last well in Kufra for any one going south toward Wadai.
From the southern Ezeila of Kufra to Arkenu is 266 km. in a nearly southeasterly direction, and there is no water or grazing on the way. From Arkenu to Ouenat is a further 42 km. in a slightly more southerly direction.
The Oases of Arkenu and Ouenat.—One of the most interesting and important results of Hassanein Bey’s expedition is the confirmation of the real existence of the oases of Arkenu and Ouenat, and a fairly exact determination of their positions and altitudes. There has long been a tradition that two oases existed in or near the southwestern corner of Egypt. Thus the map of Africa on a scale of 1:4,000,000 published by Justus Perthes of Gotha in 1892 shows an unnamed small oasis and well in Lat. 21° 51′, Long. 23° 3′, and another “uninhabited oasis,” also unnamed, about 48 km. due east of it in Lat. 21° 50′, Long. 23° 29′. Both these oases were doubtless placed on the map from vague Arab statements; they appear not to have been previously visited by any explorer, and indeed their very existence was so doubtful that they have not been shown on the maps either of the English or of the French General Staff.
I have not been able to trace any published reference to the existence of Arkenu, but that of Ouenat has been mentioned in recent papers by Mr. Harding King and Lieutenant-Colonel Tilho. In Mr. Harding King’s paper of 1913[9] on “The Libyan Desert from Native Information,” he states that he heard of a place called “Owana” or “Owanat,” about half-way along a road from Merga to Kufra, where there is a well and green grass after rain. The map appended to his paper shows that Mr. Harding King’s estimate of its probable position was Lat. 21° 37′, Long. 24° 45′, which differs by nearly 130 km. from the nearer of the two oases shown on the above-mentioned German map.
Lieutenant-Colonel Tilho, who carried out exploratory work in Tibesti, Erdi, Borkou and Ennedi in 1912-17, mentions[10] “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,” and a route he heard of from Aouinat to Merga.
Hassanein Bey’s observations give for the positions and altitude of his camps at Arkenu and Ouenat:
| Lat. N. | Long. E. | Meters above sea | |||||
|---|---|---|---|---|---|---|---|
| ° | ′ | ″ | ° | ′ | ″ | ||
| Arkenu | 22 | 12 | 32 | 24 | 44 | 15 | 598 |
| Ouenat | 21 | 52 | 29 | 24 | 54 | 16 | 616 |
Thus Ouenat is only some 34 km. from where Mr. Harding King guessed its position to be from his guide’s statements, but it is outside the somewhat wide limits of latitude indicated by Lieutenant-Colonel Tilho, and is nearly 150 km. from the place marked “uninhabited oasis” on the German map; while Arkenu, which is presumably the small oasis marked to the west of the “uninhabited oasis,” is now proved to be some 180 km. from where it is shown on that map.
It may be remarked that Arkenu is well within the boundaries of Egypt, while Ouenat is a short distance over the boundary, in the Anglo-Egyptian Sudan.
The principal interest in these places lies in the possibilities they open up for further exploration of the southwest corner of Egypt, which has hitherto been inaccessible to military patrols, and even to the boldest of explorers, by reason of the absence of any certain knowledge as to the existence and position of permanent water-supplies. Now that Arkenu and Ouenat are exactly located, with the existence of drinkable water in reasonable quantities, it may be possible for a traveler from Egypt to reach them and procure the necessary water-supplies for his return journey. I say it may be possible, for there are still great difficulties about access to Arkenu and Ouenat from Egypt, although both the compilers of the German map and Mr. Harding King were informed that an old track to Egypt runs from Ouenat. According to Mr. Harding King’s informant, the track runs to Dakhla Oasis, which is a distance of some 600 km. through a waterless desert, and consequently the journey between the two places is a very formidable undertaking for camels, even in winter; while the suitability of the ground for motor-cars, especially in the mountainous region round the oases themselves, is as yet unknown.
An interesting feature of Arkenu and Ouenat is that they are not depressions with underground water-supplies, like all the other oases of the Western Desert of Egypt, but mountainous areas where the water is dependent on local rainfall and collected in natural basins in the rocks.[11] The Nile Valley in the same latitudes has practically no rainfall, but here, some 700 km. westward into the Sahara, there is sufficient rain to maintain perennial though limited supplies—at Ouenat even sufficient for the needs of a settlement of some one hundred and fifty Badawi—and at certain seasons to provide grazing for animals in the valleys and lowlands. The ground-level in this region is high (six hundred meters above sea-level), but the mountains near the oases rise to heights of over eleven hundred meters above the sea, and it can hardly be doubted that the rainfall is connected with the orography, the mountains attracting or helping to form clouds. In this connection it is worth noting that in the more open country further south, as well as in that to the north, the absence of vegetation shows that rainfall is evidently much scarcer than in the mountains around the oases; also that Ouenat, where the mountains are higher than at Arkenu, possesses better and more abundant water. The conservation of the water through the dry season is partly conditioned by the almost impermeable nature of the crystalline rocks composing the mountains, and partly by the sheltered position of the pools in the rocky gullies, which diminishes evaporation.
The full extent of the mountains of Arkenu and Ouenat is not yet known, but they cover at least 1000 square km. Hassanein Bey’s main route lay along the western feet of the masses, so that their western limit is ascertained, as also their north and south extension; but their eastern limits in Egypt are unknown, and it is not yet certain whether there may be a continuous chain of hills connecting the two masses to the east. Hassanein Bey made a round reconnaissance extending some 40 km. eastward of his camp at Ouenat, without reaching the limits of the mass. The mountains are visible from great distances from the north and south, Arkenu having been sighted from at least 60 km. north, and Ouenat remained visible for at least the same distance on the track southward from it. There is a possibility that the mountains may be less conspicuous to a traveler approaching from the east, owing to their breaking up into smaller hills and the ground on that side of them being higher and falling away gradually toward the Nile; but this must remain uncertain until further exploration is undertaken.
From Ouenat to Erdi “Well” is a journey of 439 km. in a south-southwesterly direction, the first 284 km. being in the Anglo-Egyptian Sudan, the remaining 146 in French Equatorial Africa. There is no water in all this stretch, but patches of dried grass were met with at intervals in the latter half of the journey, and some 25 km. before reaching Erdi the valleys were full of green grass. Thus the northern limit of the equatorial rain-belt hereabouts is approximately in Lat. 18° 50′.
Erdi.—Erdi appears to be the name given to an extensive tract of country stretching between the twenty-first and twenty-fourth meridians of east longitude, rising gradually southward and ending in a broken east and west escarpment in about Lat. 18° 30′. The water-source visited by Hassanein Bey, called by the guide “Erdi Well,” is in Lat. 18° 31′, Long. 23° 10′, and is 958 meters above sea-level. It is not really a well, but a rock-pool, similar to those of Arkenu and Ouenat; the water is good.
Hassanein Bey’s “Erdi Well” is close to the locality marked “Erdi-ma” on Lieutenant-Colonel Tilho’s map of 1920, but it appears not to be the same water-source as the one visited by that traveler. Erdi Well is at the head of a small valley draining northward, and one has to ascend the hills to a height of 1020 meters above sea and cross a stretch of broken plateau before reaching the southward drainages which cut back into the scarp. Over this broken plateau Hassanein Bey proceeded in a southeasterly direction, descending the scarp in Lat. 18° 25′, Long. 23° 20′. The level at the foot of the scarp was 790 meters, so that the scarp hereabouts is some 230 meters in height.
After descending the Erdi scarp, Hassanein Bey’s track southward across the great sandy depression which separates the Erdi plateau from that of Ennedi, to Agah (88 km. from his camp north of Erdi Well), appears to have been almost parallel to, and some 20 km. east of, that followed by Lieutenant-Colonel Tilho in 1914.
Agah.—The water-source of Agah is a rock-pool similar to that at Erdi; but the water is bad, owing to fouling by animals. The pool is some 6 km. up a valley cutting back northward into the scarp which faces that of Erdi. The position found for the pool at Agah lies some 24 km. from the “Aga Spring” shown on Lieutenant-Colonel Tilho’s map. There are possibly several springs and pools among the hills in this neighborhood, all bearing the same name, which would explain the apparent discrepancy.
From Agah the track to Enebah (65 km.) runs in a rather zigzag course with a general southward trend. For the first 10 km. beyond the pool, the track ascends the valley; then, mounting rapidly, it soon reaches altitudes of over a thousand meters on the plateau.
Enebah.—Here is a small settlement of Badawi and a well of good water about 28 km. east of the wells of Keita shown on Lieutenant-Colonel Tilho’s map, on the same high plateau.
From Enebah to Bao is 120 km., by a rather zigzag track in a general south-southwesterly direction over an undulating and hilly plateau. The greatest altitude recorded by Hassanein Bey during his entire journey, 1184 meters above sea, was reached at a point on the road about 18 km. from Enebah. This altitude (3884 feet) is slightly higher than that (3600 feet) which Lieutenant-Colonel Tilho records as his maximum on the same (Erdebe) plateau at a point further west; so that the plateau probably increases in height to the eastward. The Kaptarko valley was crossed about 47 km. further on, and it is interesting to note that Hassanein Bey’s data give a position for this which is very close to the “Kapterko” of Lieutenant-Colonel Tilho’s map.
Bao.—Hassanein Bey’s Bao is not the “Bo” visited by Lieutenant-Colonel Tilho, which lies over 100 km. further north, but the place called “Orobo” on Tilho’s map and “Bao” on the map of Wadai and Darfur which was attached to the convention between the British and French Governments at Paris in 1919; this is evident from the following comparison of Hassanein Bey’s position with those scaled for the above-mentioned places from the maps referred to:
| Lat. N. | Long. E. | |||||
|---|---|---|---|---|---|---|
| ° | ′ | ″ | ° | ′ | ″ | |
| Bao (Hassanein Bey) | 16 | 28 | 24 | 23 | 1 | 47 |
| Orobo (Tilho) | 16 | 30 | 0 | 22 | 59 | 0 |
| Bao (convention map) | 16 | 28 | 0 | 23 | 4 | 0 |
The wells of Bao are at the head of a small valley draining northward, in which shrubs and trees are plentiful. There are several wells, with perennial supplies, though the water becomes scarce in the dry season and the wells have then to be deepened.
From Bao to Furawia is 145 km. in a south-southeasterly direction, over ground partly covered with grass and small trees. About 55 km. before reaching Furawia, Hassanein Bey passed close to a hill called Tameira, on which is a sign-post, formed of a dead tree, marking the boundary between French and Anglo-Egyptian territory. No astronomical observations were taken here, but Hassanein Bey’s adjusted traverse-data indicate the approximate position of the hill to be Lat. 15° 48′ N., Long. 23° 27′ E. The Wadai Hawar (“Howa” of the Anglo-French convention map) was crossed about 7 km. beyond Tameira Hill.
Conclusion.—In concluding this analysis of Hassanein Bey’s results, the reduction of which has occupied a large part of my time for over two months, I may be permitted to remark that his expedition appears to me to be an almost unique achievement in the annals of geographical exploration. The journey of 3345 km. from Sollum to El Obeid, most of it through inhospitable deserts sparsely inhabited by fanatical and predatory tribes, is one which, without a strong military escort, could have been undertaken only by a Moslem, and by one of remarkable grit, tact, and perseverance. But Hassanein Bey has not only accomplished this difficult journey and brought back interesting descriptions and photographs of the country through which he passed. Before setting out from Cairo he had applied himself strenuously for several weeks to acquiring facility in the use of the theodolite, and instruction in the particular methods of reconnaissance-survey best adapted for exploration of the kind on which he was to embark; and throughout his travels he made excellent use of the surveying knowledge thus acquired. How complete and accurate were his observations will be obvious from the foregoing analysis; and the really remarkable thing is that he managed somehow to carry out all this observation single-handed, and to maintain the continuity and accuracy of his measurements and records over the distance of more than 2000 km. which separates the points on his route whose positions were previously known. Thanks to the detailed and systematic character of his observations, their reduction has been a pleasant labor, and it has been comparatively easy to map his route and the newly discovered places along it with a high degree of accuracy.
The principal additions to our knowledge of northeastern Africa which have resulted from the expedition are:
(1) The true positions of Zieghen and Kufra, resulting in changes of about 100 and 40 kms. respectively from the positions hitherto assigned to these places on maps of Africa.
(2) The discovery of the oases of Arkenu and Ouenat, previously unknown, and the determination of their positions and approximate extent, thus opening up possibilities of new desert travel from Egypt into regions of the Libyan Desert still unexplored.
(3) The discovery of a route from southwestern Egypt across the Erdi and Ennedi plateaux of French Equatorial Africa into Darfur, and the positions of the water-sources along it. Incidentally, this establishes a connection with, and extension of, Lieutenant-Colonel Tilho’s recent brilliant explorations in the French Sudan.
(4) The determination of careful barometric levels along the entire route, affording valuable information on the orography of a vast region of which little was previously known, and confirming Lieutenant-Colonel Tilho’s conclusion that there is no possible drainage-outlet from Lake Chad in an easterly direction.
[1]Since the above was written, I have received information from the director of Sudan surveys that a recent extension of the Sudan triangulation-net includes Gebel Furawia as one of the points, and that the precise position found for the summit of the hill is Lat. 15° 20′ 59.9″ N., Long. 23° 36′ 48.1″ E., altitude 954 meters above sea-level. This position differs by about 2 km. from that shown on the map above referred to; but in view of the fact that the distance and bearing of Hassanein Bey’s camp from the hill is unknown, though his observed latitude shows his camp to have been on a parallel about a kilometer and a half north of the hill, I have not thought it worth while to make any change in the adjustment of Hassanein Bey’s data. The longitude adopted for the camp ([p. 320]) may be slightly in error, but it is unlikely that the error can exceed a mile or so. The difference of level between the top of the hill and Hassanein Bey’s camp being unknown, the triangulation-level affords no control over Hassanein Bey’s barometric value for the latter place, and consequently I have judged it best to use El Fasher as the south control point in adjusting the level-determinations.
[2]No observations are known to have been taken at Jedabia. The position given is that which I adopted for it in preparing a former map in 1921, and was arrived at by estimation from a car-and-compass traverse carried out by Captain Williams from Zuetina in 1918.
[4]Rohlfs, “Kufra,” 1881, p. 226.
[5]“Mitt. Afrik. Ges.,” Band ii., 1880-81, p. 17.
[6]“Mitt. Afrik. Ges.,” Band ii., 1880-81, p. 25.
[7]“Mitt. Afrik. Ges.,” Band ii., 1880-81, p. 23.
[8]“Geographical Journal,” Vol. 68 (1921), p. 248.
[9]“Geographical Journal,” Vol. 42 (1913), p. 282.
[10]“Geographical Journal,” Vol. 46 (1920), p. 98.
[11]Though rare in the Western Desert of Egypt, these rock-basins are common in the mountains of the Eastern Desert near the Red Sea, where they are called galts. See my “Geography and Geology of South-Eastern Egypt” (1912), p. 240. They are also abundant in the Erdi and Ennedi regions of French Equatorial Africa, as we know from the explorations of both Lieutenant-Colonel Tilho and Hassanein Bey.
APPENDIX II
Conclusions Derived from the Geological Data Collected by Hassanein Bey during His Kufra-Ouenat Expedition
W. F. Hume, D.Sc., Director, Geological Survey of Egypt
BEFORE dealing with the facts ascertained I would desire to congratulate Hassanein Bey on the successful accomplishment of an expedition which has given us knowledge of a large tract of country hitherto unknown to geographical science. Those of us who have a slight acquaintance with desert travel will appreciate the fact that he should have covered 3500 km. over an almost waterless waste in a region which from religious or political causes is practically closed to a European explorer. It has often meant weariness of body and anxiety of mind, though no doubt he has been compensated by the freedom of feeling engendered by free wind-swept spaciousness and by the constant interest of new discovery.
Hassanein Bey has shown a keen desire to obtain data which would be of scientific value, and consequently has collected specimens and taken photographs which might enable those familiar with the desert geology in Egypt to arrive at conclusions as to the geological nature of the country traversed. Mr. Moon has examined these specimens in my absence, and his notes and conclusions are attached.
The following points are those which have struck me most forcibly in looking over the specimens and photographs brought back by Hassanein Bay:
(1) Between Siwa and Jaghbub large specimens of petrified trees were noted and photographed. This is of interest as showing the wide extension to the west of the so-called “petrified forests.” It emphasizes the desirability of extending the examination of the southern edge of the Cyrenaic scarp to the western boundary of Egyptian territory, including the portion now marked “unexplored” on the 1:1,000,000 geological map of Egypt.
(2) The beautiful specimens of the Miocene oysters Ostrea Virleti and Ostrea digitalina indicate clearly that Jaghbub is on the same formation as that of Siwa, viz., Middle Miocene, while the further continuation of these strata toward Jalo is indicated by Specimen No. 3.
(3) At a point a little south of Lat. 28° N., a collection was made of hard limestone. A very shelly piece among them may be Miocene, but the others might well form part of the Eocene or Cretaceous members which are so well developed on the same latitude to the east of the Egyptian boundary. The absence of type fossils in the rocks renders further identification impossible.
(4) Between March 20 and 24 Hassanein Bey was crossing a flat plain. The question arises whether this might not be due to erosion of the finer clays and sands which so often lie between the hard Cretaceous limestone and more compact members of the Nubian Sandstone series.
(5) Be this as it may, as indicated by Mr. Moon, the Nubian Sandstone proper was met with in typical form a little north of El Harrash (Zieghen). The specimens obtained from this point onward to the junction with the igneous rocks about 30 km. north of Arkenu are all varied members of the same sandstone formation which in Egypt proper and the Sudan spreads over enormous areas.
(6) Great interest attaches to the discovery of typical granite in the oases of Ouenat and Arkenu. The main rock is of pegmatitic type, being composed of well-shaped felspars, glassy quartz, and hornblende. A point brought out by the photograph is the intense action of temperature variation on these igneous rocks. The whole of the hillside is strewn with gigantic boulders, some of which have been split into large pieces which obviously once formed part of the same block.
As regards the nature of the relations between the granite and the Nubian Sandstone, it is to be noted that the granite difference of level might be explained (a) by the existence of a fold, (b) by the presence of a fracture line or fault, (c) by intrusion of the granite when in a molten condition into the overlying sandstone.
After conversation with Hassanein Bey, and a closer examination of his photographs from this point of view, one is led to the following conclusion:
(1) A fold seems possible, because the sandstone (which dips or slopes off the granite in certain folds in the south of Kharga Oasis) is seen to be obviously dipping toward the spectator in the cinema photograph of camels coming through the valley of Ouenat. Taking (c) first, we have no proof anywhere in Egypt that granite has been intruded into the Nubian Sandstone, in all cases where the relations are clearly displayed the granite having obviously been worn down before the sandstone was deposited on it.
(2) We are consequently disposed to adopt the view, pending further study, that the differences of level may be due to the existence of a fold. The alternative would be the presence of a fracture line, along which the granite has been pushed up in a solid form to a higher level than the sandstone which normally overlies it, or the sandstone has been led down along the line of weakness against the granite.
A very interesting feature is the presence of well-made drawings of giraffes and ostriches on the granite boulders. As Hassanein Bey points out, the camel is absent, and it is to be regretted that there are no pictures of human beings. These graffiti may be of ancient date, being drawn at a period when rainfall was greater in this portion of North Africa than it is at present.
Hassanein Bey’s expedition has thus indicated that both the Miocene strata in the north and the great Nubian Sandstone formation further south continue well to the west of the western Egyptian boundary with unchanged characteristics, while the discovery of the granitic oasis, as I understand within the boundaries of Egyptian territory, opens up the possibility of developing alternative routes to Darfur from Dakhla Oasis, and also indicates a water-base of great importance in connection with the exploration of the unknown territory lying west of the route followed by Hassanein Bey. Its further study from the geological standpoint would be of great interest.
APPENDIX III
Notes on the Geology of Hassanein Bey’s Expedition, Sollum-Darfur, 1923
F. W. Moon
HAVING been requested by Hassanein Bey, in the absence of Dr. Hume, to report upon the interesting geological specimens collected by him on his recent exploratory tour through the Western Desert from Sollum, on the southern shores of the Mediterranean Sea, to Darfur in the Sudan, I have much pleasure in submitting the following short summary of the main features of the journey from a geological point of view, as deduced from the specimens collected.
Although the specimens are small and, in the case of the igneous rocks, much weathered, yet for all intents and purposes they are quite sufficient to enable one to make deductions and conclusions as to the main geological formations passed over.
As the explorer explains, there was not the freedom of transport he would have desired for making a larger collection of full-sized specimens, nor did he wish to incur the displeasure of those who formed his escort by seeming to do anything that might appear in any way suspicious, such as the constant breaking and collecting of stones.
From the tabulated list of specimens herewith appended, it may be seen that the beginning of the journey was made over Miocene formations indicated by fossil oysters and pectens (identified as Ostrea digitalina, O. Virleti, Chlamys zitteli, and others), of which there are seven valves of the former, two of the second, two of the third, and five which resemble Chlamys sub-malvinæ.
The Miocene formations continue through Siwa, Jaghbub, and Jalo, and far southward to a point about 180 km. to the south of Jalo (see Specimens 1-4), where the last Miocene specimen (No. 4) was picked up.
At this point begins a wide barren stretch of flat and desolate country, devoid of rocks of any particular geological interest beyond the thin covering of “sand and alluvium” which extends for nearly 200 km. (four days of monotonous marching) along the route to the south.
Then, when about 50 km. north of Zieghen, the explorer noticed that the aspect of the country took a sudden change; the light yellow of the Miocene limestones and desert sands gave place to brighter, more varied, and highly colored scenery, which the specimens show was due to the approach of the Lower Cretaceous Nubian Sandstones, which, wherever they occur, add beauty to the landscape in unbelievable brilliancy and variety of coloring.
Although greens and blues are sometimes observed, red is the dominant color, all shades of pink, terra-cotta, maroon, and brick red are blended together, and umbers and ochers are sometimes present.
Thus we are provided with a point well westward of any hitherto known on the northern limits of the Nubian Sandstone; in other words, the evidence suggests the continuation westward by some 600 km. of the Nubian boundary shown on the existing 1:1,000,000 colored geological map of Egypt (1910).
Mention may here be made of the apparent absence of specimens definitely representing the younger Cretaceous rocks which are shown colored green, on the map just referred to, to the east; but this may be readily accounted for by the presence of the expansive plain passed over between Jalo and Zieghen, the “sand and alluvium” covering of which is quite sufficient to hide all evidence of the younger rocks of that age.
Another question rendered obscure by the presence of this large flat expanse of “sand and alluvium” is the exact position of the southern limits of Miocene formations. If we assume (which seems to be the case) that the point, 180 km. to the south of Jalo, where the last Miocene specimens were collected, be the southern boundary of the Miocene, then we find that the distribution of that formation as now suggested is of particular interest as (1) indicating a western extension of the general outline of the ancient Mediterranean Ocean in Miocene time; and (2) adding extra weight to our conceptions as regard the period (in geological chronology) of the Egyptian-Sinai uplift which caused the elevation of land involving a considerable portion of Egypt in pre-Miocene times, and ultimately defining the shores of the Miocene Sea more or less as we now follow it from this newly discovered spot between El Harrash (Zieghen) and Jalo to a short distance east of Siwa from where it runs northeastward to the thirtieth degree of latitude, along which it continues with little variation to Suez.
It would appear that all Egypt lying between the Miocene Gulf of Suez in the east and the Siwa-Zieghen Miocene shore-line in the west and southward was dry land in Miocene times, and therefore exposed to denudation extending over a vast geological period during which the Nubian Sandstone and younger Cretaceous rocks were laid bare and in a position to have Miocene strata laid down upon or against them.
The Nubian Sandstone, as indicated by the Specimens 5-10, shows identical characteristics to those exhibited wherever it occurs in Egypt or Sinai. It is a sandstone consisting in the main of more or less fine rounded grains of pure quartz, through which are distributed, in greater or lesser proportions, larger grains or pebbles. In cases where the latter predominate, a pudding-stone or conglomerate results; where the larger grains are sparsely distributed, a porphyritic appearance is suggested.
The cementing material, which may be either calcareous, silicious, or ferruginous, is the color-imparting medium, the depth of color depending upon the amount and composition of iron oxides present in it, and when this material is weathered, washed out, and accumulated into pockets it becomes, when finely ground, suitably adapted for the manufacture of paints.
The Nubian Sandstone continues south of the Miocene-Nubian boundary above referred to, to a point some 15 km. north of the Arkenu Mountains.
Approaching this point, still another change in the general aspect of the country met the eye of the explorer: the brighter coloring of the sandstones gave place to the duller browns, grays, and blacks of an abrupt range of igneous hills, the position on the ground where the igneous rocks come up through the Nubian Sandstones being approximately 25 km. north of Arkenu.
The changes of scenery in passing from one formation to another are strikingly seen in the excellent collection of photographs procured by Hassanein Bey, who is to be highly complimented on the success he obtained under great difficulties and inconveniences.
Judging from the Specimens 11-12 submitted for examination, the igneous rocks, of which the Arkenu-Ouenat Hills are composed, consist mainly of coarsely crystalline granites and syenites varying in texture and appearance, and through them run intrusive veins of finer-grained dike rocks.
The Arkenu Hills are mostly composed of rocks represented by Specimens 12 and 14, which are really somewhat similar in composition.
No. 12 consists of a holocrystalline aggregate of large crystals of a light gray (possibly a decomposed or kaolinized orthoclase) alkali-felspar, which constitutes the main bulk of the rock. No quartz is visible in the hand specimen, which is greatly weathered, and only gives a specific gravity of a little over 2.5. Small crystals of dark greenish hornblende are well formed, and occur in fewer numbers than in Specimens 17 and 21, which are representatives of the rockmass of the Ouenat Hills to be described presently.
Specimen 14 is an unweathered gray rock chiefly composed of a mottled gray alkali-felspar, with hornblende crystals in similar numbers to those in Specimen 12.
The microscopic examination of a rock-section made from Specimen 14 corroborates the above description, but introduces the possibility of the presence of nephelin in granular-like patches in the slide, which correspond to darker slightly lustrous areas in the hard specimen; however, no nephelin has been actually identified.
Specimens Nos. 12 and 14 may therefore be called syenites.
Running through the syenites of the Arkenu Hills are veins of intrusive rocks represented by Specimens Nos. 11, 13, and 15, and no doubt many others occur.
Specimen No. 11 represents a vein of a hemicrystalline, hard dark green rock weathering brown on the outer surface, with innumerable small dark specks which are scarcely discernible in the unweathered portion of the specimen.
Under the microscope this rock is found to be of considerable interest. It consists of an aggregate of small phenocrysts of idiomorphic felspar, which in places assumes the appearance of a crypto- or microcrystalline felspathic matrix crowded with acicular crystals of a green mineral resembling ægirine. The latter are in places irregularly distributed, but in areas where the felspar occurs in roughly rectangular or lozenge form, the ægirine microlites are crowded round the edges of the latter.
No quartz is noticeable in the rock-slide, and the rock may be tentatively determined as an ægirine-felsite, apparently similar to a rock described and figured in Harker’s “Petrology for Students.”
A second vein in the Arkenu Hills is represented by Specimen No. 13, which is a brownish quartzite.
The third vein is indicated by Specimen No. 15, which is a dark gray laminated rock, weathering to reddish brown, very fine in texture, with small clear crystals of phenocrysts sparsely disseminated through the ground-mass. The rock-slide shows, under the microscope, a great similarity to Specimen No. 11 as described above. The felspar here, however, forms a much finer crypto-crystalline ground-mass than in the former, and the ægirine microlites are smaller, tapering, and not so well formed. This rock may also be tentatively called a fine ægirine-felsite.
The Ouenat Hills are mainly composed of rocks represented by Specimens 17 and 21, the chief constituent of which is a gray alkali-felspar (possibly orthoclase with some microcline). Quartz is well represented in idiomorphic forms; no mica is noticeable in the hand specimens, but many well-developed prismoidal crystals of very dark or dark green hornblende are thickly distributed throughout the mass.
No slide was made of these specimens owing to their fragile condition on account of weathering, but the rock may be determined as a coarsely crystalline gray hornblende granite.
Specimen No. 18 is another representative rock from, and constitutes a considerable bulk of, the Ouenat Hills. It may be termed a red granite, approximating to an aplite with very little mica, which decomposes and forms oxides of iron which have stained the rock a brownish red; quartz and felspar form the main bulk of the rock.
As in the case of the Arkenu syenites, so here in the Ouenat granites we find other examples of endogenous veins running through the parent rock, represented by Specimens 16, 19, and 22.
Specimen No. 16 represents a vein of purplish felsite, in the felsitic ground-mass of which occur phenocrysts of idiomorphic felspar.
Specimen No. 19 represents a vein of pure white granular quartz rock which occurs in and may have been the cause (through denudation) of the cave found in the foot-hills of the Ouenat range.
Specimen No. 22, found at Garet Shezzu, is a typical quartzite which may also occur as a vein in the granites.
Two specimens found inside the cave in the Ouenat Oasis are of particular interest. These specimens are Nos. 20 and 21. The former, a laminated travertine, could only have been deposited from running water, as the formation of ripple-markings confirms; and from notes made by the explorer at the time of his inspection, we learn that there was quite a lot of it lying about on the floor of the cave. Under the microscope spheroidal structure is displayed, representing the ripple-markings, and in the matrix of calcite many fragments of quartz, felspar, etc., are conspicuous, these having been derived from the denuding granites. No organic remains were observed.
The second specimen (No. 21) is a fragment of the hornblendic granite of which the Ouenat Hills are chiefly composed, and which forms the roof of the cave; this is coated on one side with a thin black iron-manganese film, similar to the well-known deposit on the rocks in the Nile at or near the Asswan Dam.
This whole igneous area, which includes the newly discovered mountains and oases of Arkenu and Ouenat, is possibly of limited extent, and occurs in, and is possibly surrounded by, a much wider expanse of Nubian Sandstone, in a similar manner to several other such areas already shown on the 1:1,000,000 geological map of Egypt.
Judging from other known similar occurrences where igneous rocks appear surrounded by Nubian Sandstones, we may infer that the latter were deposited upon the ancient igneous rocks which subsequently rose vertically, bending the superincumbent strata over and round them, possibly only to a slight degree in this instance, as none of the photographs show very highly dipping rocks.
On leaving Ouenat for Erdi the igneous area is soon left behind. The actual junction between it and the Nubian Sandstone (which again forms the surface rock) occurs at a point about 20 km. south of Ouenat, and the aspect of the country again changes from the more uneven weathering of the igneous range of grays and browns to brilliant colorings of the Nubian Sandstone which forms a long series of prominent escarpments rising to heights bordering on 1000 meters above the sea between Enebah and Kuttum, after which the ground begins to fall, until El Fasher is reached, where the ground-level is only about 700 or 800 meters in height.
Summary.—The several interesting geological features suggested by the recent expedition may be summarized as follows:
1. That Miocene rocks extend southward, to or near the twenty-seventh degree of north latitude, forming a large bay bordered by older rocks.
2. That the Miocene rocks, resting here apparently upon or against Nubian Sandstones, seem to follow the same conditions noticed first by Dr. Hume in the Gulf of Suez region, namely, that they rest upon older and older formations the further southward they are found; in other words, that prior to the deposition of the Miocene there was a time of denudation which was more effectual in the south than in the north, owing to the fact that in the south was an area of greater uplift.
3. That a large area of Nubian Sandstone (Cretaceous) exists south of this latitude.
4. That a newly discovered range of igneous rocks in the Arkenu Hills exists well inside Egyptian territory, and possibly entirely within this Nubian Sandstone area, or connected as a tongue to a larger igneous massif lying in the south.
5. That the Cretaceous rocks (younger than the Nubian Sandstone) which appear on the colored Geological Map of Egypt further to the northeast, possibly do not occur along the route traversed, having been concealed beneath “sand and alluvium” areas.
List of Specimens Collected by Ahmed Mohammed Hassanein Bey in His Expedition from Sollum to Darfur
| No. | Date 1923 | Locality (As taken from descriptions on labels) | Determination of Specimens |
|---|---|---|---|
| 1 | — | Siwa | Three crystal fragments of selenite; one pecten and two oyster shells (possibly of Miocene age) |
| 2 | — | Jaghbub | One pecten in a shelly limestone (possibly indicating Miocene age) |
| 3 | — | Surface rocks on the way from Jaghbub to Jalo | One piece of fossilized wood; three loose silicious pebbles; two long concretions of calcareous grit, and fibrous salt crystal (curved, five inches long) |
| 4 | March 20 | In Wadai, in small patches | Two loose pebbles of calcareous grit with quartz grains |
| 5 | March 24 | Getting near El Harrash (Zieghen), patches of this strewn (broken) before reaching Halab | Nubian Sandstone (one specimen) |
| 6 | March 28 | One day’s journey from El Harrash (Zieghen), on way to Kufra | Hard ferruginous bands from Nubian Sandstone (five specimens) |
| 7 | March 29 | Garet El Sherif | Nubian Sandstone (three specimens) |
| 8 | — | Gebel El Neri, garas nearing Hawari | Ferruginous bands (color maroon) from Nubian Sandstone (three specimens); one black ferruginous “bomb” |
| 9 | — | Kufra (Taj) hills | Blocks of Nubian Sandstone (three specimens) |
| 10 | April 22 | Between Kufra and Ouenat; specimens from chain of hills crossed that day | Nubian Sandstone (one specimen); and ferruginous bands from Nubian Sandstone (two specimens) |
| 11 | April 24 | Arkenu Mountain | Igneous rock (ægirine felsite) |
| 12 | April 24 | From patches of Arkenu Mountain; there are big hills formed entirely of it . . . on the outside of the mountain | “ (badly weathered syenite) |
| 13 | April 24 | From big patches north of Arkenu Mountain | “ (quartzite vein in) |
| 14 | April 25 | From Arkenu Mountain itself | “ (gray syenite) |
| 15 | April 25 | Found in big blocks buried in the ground on the border of Arkenu Mountain, in the Arkenu valley | “ (ægirine felsite) |
| 16 | — | Specimen from formations (in layers) found in Ouenat big valley | “ (felsite) |
| 17 | — | Ouenat Mountain is mostly of this stone | “ (badly weathered hornblende-granite |
| 18 | — | Stone of which Ouenat is generally formed | “ (badly weathered granite) |
| 19 | — | Found inside the water-cave at Ouenat, near the water-level; plenty of it in small patches | “ (quartz vein) |
| 20 | — | Found inside the water-cave at Ouenat | Calcareous deposit from running water (travertine) |
| 21 | — | Found inside the water-cave at Ouenat, in the roof; most of the stone of the cave and mountain is of this kind | Igneous rock (badly weathered hornblende-granite, coated with polished film of iron which may have come from the water) |
| 22 | May 8 | From Garet Shezzu, near Ouenat | “ (fine quartzite) |
| 23 | May 10 | Between Ouenat and Erdi | Nubian Sandstone (one specimen) |
| 24 | May 13 | Found strewn on red sand, getting near Erdi; nothing but red sand and this stone | Ferruginous band (containing hematite) from Nubian Sandstone |
| 25 | May 16 | Erdi Hills | Dark red clay, with small percentage of quartz sand (grinds up into dark brick-red powder) |
| 26 | May 16 | Stone of Erdi Hills | Brick-red clay, with small percentage of quartz sand (grinds easily into bright, brick-red colored powder) |
| 27 | May 19 | Agah Hills | Soft, fine, yellow to red, slightly calcareous micaceous sandstone |