Page:EB1911 - Volume 19.djvu/702

 rapids—though not such a hindrance to navigation—are of a more dangerous character than any encountered between Ansongo and Say. “In one pass, some 54 yds. wide, shut in between two large reefs, a good half of the waters of the Niger flings itself over with a tremendous roar” (Hourst). The rapids extend for 50 m. or more; in a less obstructive form they continue to Rabba, but light-draught steamers ascending the stream during flood season experience little difficulty in reaching Bussa. A little above Rabba the river makes a loop south-west, at the head of the loop being (right bank) Jebba. Here the river is bridged by the railway from Lagos. Sixty miles lower down is the mouth of the (left hand) tributary the Kaduna, a river of some magnitude which gives access to Zungeru, the headquarters of the British administration in Northern Nigeria. The head waters of the Kaduna are not far from Kano. Below the mouth of the Kaduna, on the right bank of the Niger, is Baro, the starting-point of a railway to Kano. In 7° 50′ N. 6° 45′ E. the Niger is joined by its great tributary the Benue. At their confluence the Niger is about three-quarters of a mile broad and the Benue rather more than a mile. The united stream forms a lake-like expansion about 2 m. in width, dotted with islands and sandbanks; the peninsula at the junction is low, swampy, and intersected by numerous channels. On the western bank of the Niger at this point is situated (q.v.), an important commercial centre. The stream, as far south as Iddah (Ida), a town on the east bank, rushes through a valley cut between the hills, the sandstone cliffs at some places rising 150 ft. high. Between Iddah and Onitsha, 80 m., the banks are lower and the country flatter, and to the south of Onitsha the whole land is laid under water during the annual floods. Here may be said to begin the great delta of the Niger, which, extending along the coast for about 120 m., and 140 or 150 m. inland, forms one of the most remarkable of all the swampy regions of Africa. The river breaks up into an intricate network of channels, dividing and subdividing, and intercrossing not only with each other but with the branches of other streams, so that it is exceedingly difficult to say where the Niger delta ends and another river system begins. The Rio Nun is a direct continuation of the line of the undivided river, and is thus the main mouth of the Niger.

From the sea the only indication of a river mouth is a break in the dark green mangroves which here universally fringe the coast. The crossing of the bar requires considerable care, and at ebb tide the outward current runs 5 knots per hour. For the first 20 m. (or as far as Sunday Island, the limit of the sea tide in the dry season) dense lines of mangroves 40, 50, or 60 ft. in height shut in the channel; then palm and other trees begin to appear, and the widening river has regular banks. East of the Nun the estuaries known as the Brass, Sombrero, New Calabar, Bonny, Opobo (or Imo), &c. (with the exception, perhaps. of the first-named), seem to derive most of their water from independent streams such as the Orashi, rising in about 6° N., which is, however, linked with the Niger by the Onita Creek in 5° N. Behind the town of Okrika, some 30 m. up the Bonny river, the swampy ground gives place to firm land, partially forest-clad West of the Nun all the estuaries up to the Forcados seem to be true mouths of the great river, while the Benin river, though linked to the others by transverse channels, may be more properly regarded as an independent stream. (See .) In this direction the largest mouth is the Forcados, a noble stream with a safe and relatively deep bar. Its banks in its lower course are densely wooded, but the beach is sandy and almost free from marsh and malaria. The mouth is 2 m. wide. It has supplanted the Nun river as the chief channel of communication with the interior. There are 17 to 19 ft. of water over the Forcados bar, as against 13 ft. at the Nun mouth. Moreover the Forcados bar shifts little laterally, and within the bar is a natural harbour with an area of 3 to 4 sq. m. having a depth of 30 ft. at low water spring tides. From the mouth of the Forcados to the main stream is 105 m., with a minimum depth in the dry season of 7 ft. A northern arm affords ocean-going vessels access to Wari and Sapele. The other western mouths of the Niger have as a rule shallow and difficult bars. The delta is the largest in Africa and covers 14,000 sq. m.

The Benue is by far the most important of the affluents of the Niger. The name signifies in the Batta tongue “Mother of Waters.” The river rises in Adamawa in about 7° 40′ N. and 13° 15′ E., a little north of the town of Ngaundere, at a height of over 3000 ft. above the sea, being separated by a narrow water parting from one of the headstreams of the Logone, whose waters

flow to Lake Chad. In its upper course the Benue is a mountain torrent falling over 2000 ft. in some 150 m. With the Chad system it is connected by the Kebbi or Mayo Kebbi, a right-hand tributary whose confluence is in about 9° N., 13° E. The Kebbi, fed by many torrents rising in the eastern versant of the Mandara Hills, issues from the S.W. end of the Tuburi marshes. These marshes occupy an extensive depression in the moderately elevated plateau east of the Mandara Hills, and are cut by 10° N., 15° E. The central part of the marshes forms a deep lake, whence there is a channel going northward to the Logone and navigable for some months during the year. The Kebbi flows west, and soon after leaving Tuburi passes through a rocky barrier marked by a series of rapids and a fall at Lata of 165 ft. Below these obstructions the Kebbi to its junction with the Benue has a depth of not less than 6 ft. In places, as at Lere and Bifara, it widens into lake-like dimensions.

Below the Kebbi confluence the Benue, now a considerable river, turns from a northerly to a westerly direction and is navigable all the year round by boats drawing not more than 2 ft. For some 40 m. below the confluence the river has an average width of 180 to 200 yds., and flows with a strong steady current, although a broad strip of country on each side is swampy or submerged. It is here joined by the Faro, which, rising in the Adamawa Mountains S.E. of Ngaundere, flows almost due north. About 50 m. below the junction of the Faro is Yola, the capital of Adamawa. It lies on the southern side of the Benue, some 850 m. by river from the sea and at an altitude of 600 ft. Here the width of the stream increases at flood time to 1000 or 1500 yds., and though it narrows at the somewhat dangerous rapids of Rumde Gilla to 150 or 180 yds., it soon expands again. About 50 m. below Yola the Benue receives, on the right bank, the Gongola, which rises in the Bauchi highlands and after a great curve north-east turns southward. It is over 300 m. long, and at flood time is navigable for about half of its course. The Benue receives several other tributaries both from the north and the south, but they are not of great importance. It flows onwards to the Niger with comparatively unobstructed current, its valleys marked for the most part by ranges of hills and its banks diversified with forests, villages and cultivated tracts. But though exceptionally free from obstruction by rapids, the river falls very low in the dry season, and for seven to eight months is almost useless for navigation. The Benue lies within British territory to a point 3 m. below the mouth of the Faro, in about 13° 8′ E. East of that point the river is in the German colony of Cameroon.

As the Niger and the Benue have different gathering grounds, they are not in flood at the same time. The upper Niger rises in June as the result of the tropical rains, and decreases in December, its breadth at Turella expanding from between 2000 and 2500 ft. to not less than 1 m. The middle Niger, however, reaches its maximum near Timbuktu only in January; in February and March it sinks slowly above the narrows of Tosaye, and more rapidly below them, the level being kept up by supplies from backwaters and lakes; and by April there is a decrease of about 5 ft. In August the channel near Timbuktu is again navigable owing to rain in the southern highlands. The Benue reaches its greatest height in August or September, begins to fall in October, falls rapidly in November and slowly in the next three months, and reaches its lowest in March and April, when it is fordable in many places, has no perceptible flow and at the confluence begins to be covered with the water-weed Pistia Stratiotes. The flood rises with great rapidity, and reaches 50, 60, or even 75 ft. above the low-water mark.

The two confluents being so unlike, the united river differs from each under the influence of the other. Here the river is at its lowest in April and May; in June it is subject to great fluctuations; about the middle of August it usually begins to rise; and its maximum is reached in September. In October it sinks, often rapidly. A slight rise in January, known as the yangbe, is occasioned by water from the upper Niger. Between high- and low-water mark the difference is as much as 35 ft.

The geological changes which have taken place in the Niger basin are imperfectly known. The French scientists E. F. Gautier and R. Chudeau, summing up the evidence available in 1909, set forth the hypothesis that the existing upper Niger and the existing lower Niger were distinct streams. According to this theory the upper Niger, somewhat above where Timbuktu now stands, went north and north-west and emptied into the Juf, which in the beginning of the quaternary age was a salt-water lake, the remnant of an arm of the sea which in the tertiary age covered the northern Sudan and southern Sahara as far east as Bilma. Lake Fagubini is regarded as a remnant of the