504 DEPOSITS OF THE NILE. 



As I have observed, the area of cultivated soil is much less 

 extensive now than under the dynasties of the Pharaohs and the 

 Ptolemies ; for — ^though, in consequence of the elevation of the 

 river-bed, the inundations now have a wider natural spread — the 

 industry of the ancient Egyptians conducted the Nile water over 

 a great surface which it does not now reach. 



Had the Nile been banked in, hke the Po, all this deposit, ex- 

 cept that contained in the water diverted by canals or otherwise 

 drawn from the river for irrigation and other purposes, would 

 have been carried out to sea. This would have been a consider- 

 able quantity ; for the Nile holds some earth in suspension at all 

 seasons except at the very lowest water, a much larger proportion 

 during the flood, and irrigation must have been carried on during 

 the whole year. The precise amount of sediment which would 

 have been thus distributed over the soil is matter of conjecture, 

 but though large, it would have been much less than the inunda- 

 tions have deposited, and continuous longitudinal embankments 

 would have compelled the Nile to transport to the Mediterranean 

 an immense quantity over and above what it has actually deposit- 

 ed in that sea. The Mediterranean is shoal for some miles out to 

 sea along the whole coast of the Delta, and the large bays or 

 lagoons within the coast-line, which communicate both with the 

 river and the sea, have little depth of water. These lagoons the 

 river deposits would have filled up, and there would still have 

 been surplus earth enough to extend the Delta far into the Medi- 

 terranean.* 



conclude that the delta of the Mississippi began its encroachments on the Guli 

 of Mexico not more than 4,400 years ago, before which period they suppose 

 the Mississippi to have been "a comparatively clear stream," conveying very 

 little sediment to the sea. The present rate of advance of the delta is 262 feet 

 a year, and there are reasons for thinking that the amount of deposit has long 

 been approximately constant. — Report, pp. 435, 436. 



* The present annual extension of the Delta is, if perceptible, at all events 

 very small. According to some authorities, a few hectares are added every 

 year at each Nile mouth. Others, among whom I may mention Fraas, deny 

 that there is any extension at all, the deposit being balanced by a secular de- 

 pression of the coast. 



EUsee Reclus states that the Delta advances about 40 inches per year. — La. 

 Terre, l, p. 500. 



