Vol. 52.] PROF. E. HULL ON THE GEOLOGY OF THE NILE VALLEY. 313 



description applies, with slight modification, to the whole valley as 

 far as Assuan, and also between this and the Second Cataract, 

 as may he gathered from the descriptions of Prof. Leith Adams and 

 Capt. Lyons. The following section, taken across the valley at 

 Farshut, is intended to show its general structure : — 



Pig. 3. — Section at Farshut. 



Terrace 1. — Liable to floods. Cultivated. 



Terrace 2. — Older. Beyond the reach of floods. 



Terrace 3. — Plateau of Eocene limestone at the border of the Desert. 



That terrace No. 2 was originally the bed of the Nile there cannot 

 be a doubt, and the occurrence of fluviatile shells in the strata 

 is not required to strengthen this view. These were found by 

 Leith Adams both above and below the First Cataract. Where 

 I examined the beds, at Thebes and Assuan, I was not so fortunate 

 as to find them. I will now mention a few localities where terrace 

 Xo. 2 may be observed above Girgeh. 



(a) Girgeh. — Where the valley widens a short distance above 

 Girgeh, terrace No. 2 is distinctly seen, rising, say, about 80 to 100 

 feet above the cultivated terrace (No. 1). The level is rather 

 higher than that farther up the valley. This may be accounted for 

 by the Pliocene submergence, which would have affected the level 

 of the river nearly as far as Girgeh ; to this I shall again have to 

 refer. 1 



(6) Above Kasr-es-Sayad the western escarpment of the Eocene 

 limestone recedes for a great distance from the river-side, and here 



1 Dawson believes that the sea-waters reached as far as the First Cataract, 

 supposing the 500-foot caves and terrace above the Nile at Gebel Mokattam to 

 be due to submergence, which is uncertain in the absence of marine forms at 

 this level. But the only certain raised sea-beach — that discovered by Prof. Fraas 

 — is nearly 300 feet lower, and the sea-waters in this would not have reached 

 farther than Girgeh, as above stated. 



[For this determination I am indebted to Mr. Garstin, Chief of the Egyptian 

 Public Works Department, who kindly sent me the following statement while 

 this paper was passing through the press : — 



• Distance from Cairo in kilometres at which the high-water level was 

 220 feet over the sea : 



1890=562 kilometres from Cairo. 



1891=563 



1892=558 



1893=566 



1894=560 



1895=564 



' The mean is 563 kilometres from Cairo,' or 33957 miles. This distance 

 would reach to within 2 miles of Girgeh, which is 3414 miles from Cairo. — 

 April 25th, 1896.] 



