

* 





-1 





fc 





1 



z 



' pecu- 1 



I 



gnnel, 



' clouds 

 narrow 



in 



'X 



rroimd- 



rapora- 

 durinj 

 lonths. 



- fan 



being 



and 

 durii- 



abc-v 

 land. 



tli 







Ch. XVIII. ] 



DELTA OF THE NILE. 



433 



near 



north, or from the coast to the head of the delta 

 Cairo (or the ancient site of Memphis, thirty miles distant) 

 is about 100 miles. In this region the rate of the deposition 

 of sediment is considerably less than in the alluvial plain 

 above, owing to the wide spread of the waters east and west. 

 The height of the river at Asouan or the ancient Philoe, 

 where the first cataract occurs, is 300 feet above its level at 

 Cairo, a distance of 555 statute miles, following the course of 

 the river, which gives an average fall of rather more than 



half a foot (6-486 inches) per mile ; but the fall between the 

 head of the delta and the sea is much less considerable. 



to Sir J. G. Wilkinson, the alluvial matter formed 

 in 1,700 years on the land about Elephantine, or near the first 

 cataract, lat. 24° 5', is about 9 feet in thickness ; at Thebes, 

 lat. 25° 43', about 7 feet in the same period ; and at Heliopolis 

 and Cairo, lat. 30°, about 5 feet 10 inches ; and the amount 



Nile, lat. 31° 30'. 



mouths 



Nile 



always keeps pace with the general 

 elevation of the soil of Egypt, and the river-banks, like 



Mississippi 



(see p. 413), are 



much higher than the flat land at a distance, so that they 



mentioned 



highest inundations. In consequence of the gradual rise of 

 the river's bed, the annual flood is continually spreading over 

 a wider area, and the alluvial soil encroaches on the desert, 

 covering, to the depth of several feet or yards, the base of 

 statues and temples which the waters never reached 3,000 

 years ago. Although the sands of the Libyan deserts have 

 m some places been drifted into the vallev of the 



Nile 



more 



balanced by the fertilising effect of the water which now 

 reaches farther inland towards the desert, so that the number 

 ot square miles of arable soil is greater at present than at any 

 previous period. 



The composition of the Nile-mud resembles very closely 

 that of the Loess or old inundation mud of the Rhine, and, 

 according to a careful analysis by Lassaigne * bears a singu- 



VOL. I. 



* Quart. Geol. Journ. 1849, vol. y. p. 20. Memoirs. 



F F 



*i 



