Page:Africa by Élisée Reclus, Volume 3.djvu/167

 THE SENEGAL BASIN. 131 flow in the dry season, but for the natural barriers dividing its course into a series of basins with an almost imperceptible current between the periods of high water. During the rainy winter season the stream passes by so many rapids from ledge to ledge of these dams, which are again exposed in the rainless months. At the confluence of the Bakhoy and Bafing, the Senegal is still 470 feet above sea-level, and its bed being confined between banks from 100 to 120 feet high, the stream rushes from rapid to rapid, at that of Guina falling in a single plunge from a height of over 50 foet with a mean breadth of 1,600 feet. The Felu Falls, the last of the series, are of the same height, but here the river is much more contracted. At the foot of the cataract it reaches a level of 220 feet above the sea, from which it is still distant some 600 miles. Hence, the mean incline is here very slight, so that during the season of high water large craft are able to ascend as far as the falls. A little farther down the Senegal receives its chief northern affluent, the Kuniakari, or Tarakole, which has a total length of at least 120 miles. But the contributions of this feeble Saharian tributary are as nothing to those of the Faleme, which joins the main stream lower down after collecting the copious waters of the Futa- Jallon uplands. Rising near the Bafing and Gambia, the Faleme sends down a little water even in the dry season, while in winter it is no less than 1,000 feet broad and 26 feet deep at the confluence. It might be navigated for some hundred miles by small craft, but its upper basin, unhealthy and frequently wasted by wars, has been very little explored, comprising the least known part of French Sudan. Below the Faleme junction the Senegal receives no more perennial tributaries, for it here flows north-west beyond the region of copious rains, and penetrates into the zone of transition between Sudan and the desert proper. Several of the inter- mittent Saharian wadies run out in saline marshes, which in a drier climate would be converted into salt-pans like those of Ijil and other parts of the desert. During the dry season the volume of the main stream gradually diminishes, developing long meanders and winding sluggishly round numerous idands, such as the long alluvial land of Bilbas, and the island at Morfil, or " Ivory," so called from the elephants which formerly frequented it. The river bed is intersected at intervals by several rocky ledges, none of which, however, is high enough to com- pletely arrest the stream. But at low water boats have great difficulty in forcing the passage, and the riverain populations are able to ford the current at many points. In the lower reaches small steamers can always ascend as far as Maf u above Podor, 210 miles from the sea ; but this is due to the tides, which convert the lower course of the Senegal into a marine estuary. The discharge during the dry season is estimated at not more than 1,760 cubic feet per second. The great rains, which begin in May on the Futa-Jallon highlands, change the whole character of the river. The water rises rapidly, and from June to October large steamers ascend to the foot of the Felu Falls. At Bakel the floods rise 50 feet and upwards, at Matam 30 to 34, at Podor 20, at Dagana little more than 14, the inundations thus diminishing as they approach the sea. But at this season the