GEOLOGICAL HISTORY OF BGYPT AND THE NILE VALLEY. 333 
were on the coast in historic times; and on a former occasion 
I have shown how this fact solves a difficulty regarding the 
passage of the Red Sea by the Israelites under Moses, which 
must occur to every Biblical student who regards the present 
limits of sea and land as conterminous with those in exist- 
ence at this eventful epoch. The Isthmus of Suez, as far as 
the great Bitter Lakes, is an old sea-bed, and was no doubt 
under water at the time of the Exodus.* 
Attempts have been made to estimate the iength of time 
required for the deposition of the alluvial deposits of the 
Nile Delta from data observed regarding the rate of deposi- 
tion within historic times. Such estimates can never be 
more than very loose approximations, because the present 
rate of deposition may be very different from that of previous 
years. In the earlier years of the recent period, deposition, 
as well as erosion, were in all probability more rapid than 
subsequently. Sir J. W. Dawson, on an assumption of one- 
fifteenth of an inch per annum, arrives at the conclusion 
that the length of time required would be about 5000 years, 
and that from the period to be allowed for the colonisation 
of Egypt since the Paleeocosmic age is about B.C, 3000 years.f 
The computations of authorities on the periods of Egyptian 
dynasties are at present hopelessly at variance. Fortunately 
for us, they are outside the scope of this paper.t 
The Cuarrman (H. Capman Jones, Esq., M.A.).—I am sure all 
will accord their best thanks to Professor Hut for this paper, which 
opens our 1891 Session. 
Captain F. Perris, F.G.S. (Honorary Secretary).—The following 
communications have been received. 
The first is from Professor T. Rupert Jones, F.R.S., who, 
in making some suggestive remarks, says: ‘I should like to 
state what I think of the paper; it is a careful and satisfactory 
account of the physical structure and physical history of Egypt, 
and certainly it is a good example of the necessity of a know- 
ledge of geology in depicting geographical features. I do not 
know that any remarks are needed on the clear and_ useful 
description of the strata and their relative position, and their effect 
on the constitution of land surface.” 
* 
* Mount Seir, Sinai, and Western Palestine (1884). 
t Dawson, Modern Science in Bible Lands, p. 330. 
{ Thus M. Mariette places the First Dynasty at a period B.c. 5004, 
while Professor Lepsius places it at B.c. 3892, a difference of 1112 years ! 
