308 PROF. B. HULL ON THE GEOLOGY OE THE NILE VALLEY. [May 1 896, 



17. Observations on the Geology of the Nile Valley, and on the 

 Evidence of the Greater Volume of the Eiver at a Former 

 Period. By Prof. Edward Hull, M.A., LL.D., F.R.S., F.G.S. 

 (Read February 26th, 1896.) 



Part I. 



1. Introductory. 



The evidence in favour of the view that the Nile was at one period 

 a river of vastly greater volume than at the present day is so 

 remarkable that it has forced itself on the attention of several 

 writers, amongst whom may be specially mentioned the late Prof. 

 Leith Adams, 1 Prof. Zittel, 2 and Capt. Lyons 3 ; and to the state- 

 ments coming from such competent observers I should hardly have 

 thought it necessary to add any of my own, were it not that I 

 find from personal intercourse that geographers have failed as yet 

 to grasp the full significance of the phenomena bearing on the 

 subject and described by the above-named authors. When about 

 to leave for a recent visit to the Nile Valley, I wrote to Prof, (now 

 Sir) Joseph Prestwich, enquiring whether he thought there were 

 any problems to which a travelling geologist might give attention 

 with some prospect of enlarging our knowledge of the physical 

 conditions of that remarkable line of country, and in reply he 

 recommended me to pay special attention to the terraces. This 

 advice I endeavoured to keep before my mind during my ascent 

 as far as the First Cataract and the return journey ; and I venture 

 to lay before the Society the impressions that I then received, and 

 the conclusions that I have drawn from them regarding the volume 

 and dimensions of the river at a prehistoric period. But, before 

 entering upon this special subject, I wish to note a few points con- 

 nected with the geological structure of the Nile Valley, which 

 came under my notice, although they may not be altogether new. 



2. Some Points in the Geology of the Nile Valley. 



And first let me observe that it is only by personal examination 

 that one can realize the extent of the erosion by old river-action 

 which was carried on after the Libyan region had been elevated out 

 of the waters of the sea at the close of the Eocene period. That 

 this erosion was accomplished mainly during the succeeding Miocene 



1 Leith Adams, 'On the Geology of a Portion of the Nile Valley, etc., with 

 Note on the Shells, by S. P. Woodward,' Quart. Journ. Geol. Soc. vol. xx. 

 (1864) p. 6. 



2 Zittel, 'Beitrage zur Geologie und Palaontologie der Libyschen Wiiste/ 

 Palseontograpbica, vol. xxx. pt. i. 1883. 



3 Lyons, ' On the Stratigraphy and Physiography of the Libyan Desert of 

 Egypt,' Quart. Journ. Geol. Soc. vol. 1. (1894) p. 531. 



