30 GEOLOGY 



stream at Damer and Khartoum respectively. By far the 

 greater mass of the soil brought down by the river is de- 

 posited towards its present mouth, and forms the Delta. 

 Now the real Delta of the Nile is that flat triangular portion 

 of Egypt having for its apex Memphis, more than onehundaed 

 miles from the sea, and its base formed by a coast-line two 

 hundred miles in length, Port Said being at its eastern angle ; 

 so that the real Delta contains an area of one hundred square 

 miles, while that portion of Lower Egypt commonly known 

 as the Delta, has Cairo at the apex of the triangle, and is 

 bounded on the east by the Damietta and on the west by 

 the Rosetta branches of the Nile, allowing only an extent of 

 ninety miles for its base or coast-line ; so that the portion 

 usually spoken of as the Delta is not half the real Delta of 

 the Nile. 



The rate of deposit and the time required for the formation 

 of the Delta must be purely hypothetical, as all the bones 

 and shells which have been discovered are similar to those 

 now existing in the Nile or living on its banks ; and as no pit 

 has been sunk below the sea-level, the absence of marine 

 shells in these deposits is not surprising ; and probably even 

 if such a pit M'ere sunk, it would pass through river-alluvium 

 for a considerable depth below the sea-level, as has almost in- 

 variably proved to be the case when like experiments have been 

 conducted in other Deltas. Besides, we have evidence that 

 the Delta has been slowly sinking for a considerable time, as 

 we already remarked when we visited " Cleopatra's Baths," 

 which are now below the level of the sea ; and beneath the 

 waters of Lake Menzaleh may be seen the banks of some 

 ancient arm of the Nile, as well as the ruins of a town. 



The rate of yearly deposit is undoubtedly very small ; and 



