604 T. Barron — Miocene Beds between Cairo and Suez. 



rocks of Egypt, this author points out that, previous to his own 

 examination of the area at Mogara in the Libyan Desert, no Lower 

 Miocene beds were known in Egypt. Up to the present this is the 

 only occurrence, but he points out that strong probability exists 

 that these beds will be found in the district between Cairo and Suez, 

 although none have been proved. After discussing and comparing 

 the Petrified Forest near Cairo with that occurring at Mogara, which 

 this author regards as Lower Miocene, he finally decides to put the 

 gritty beds occurring above the basalt to the east of Cairo, together 

 with the Petrified Forest in part, into the Lower Miocene. For 

 this he has no fossil evidence whatever; and it is only from the 

 resemblance between the lithological characters of the beds, and 

 the fact that fossil wood occurs at the base of the Miocene in Mogara 

 (a fact of little stratigraphical value since fossil trees are known 

 from the Upper Eocene, and Oligocene on the other side of the 

 Nile Valley), that he ventures to assign to these beds a Lower 

 Miocene age. 



In the course of this paper it will be shown that this decision 

 is partly right, though in the main it is wrong, while in a later paper 

 it is hoped that the much vexed question of the age of the Petrified 

 Forest in this neighbourhood, with its associated lava-flows and 

 thermal springs, will be definitely' settled. 



In order to better understand the occurrence of the beds in 

 question, a brief sketch of the geological history of the period 

 immediately preceding the Miocene is necessary. After the close 

 of the Eocene period, the land on the east side of what is now the 

 Nile Valley rose from under the sea and became dry land. This 

 was the beginning of a continental period which persisted throughout 

 Oligocene times. While in the district round the Fayum the 

 sedimentation continued unbroken from the highest Eocene into the 

 Lower Oligocene, on the east side of the present Nile Valley 

 denudation was at work removing the Upper Eocene beds and 

 producing the relief seen wherever the Gebel Ahmar Sands have 

 been removed. Then these sands and gravels with drifted trees 

 were deposited in a lagoon or estuary. These probably represent 

 the upper part of the Lower Oligocene. After the sedimentation of 

 these sands had continued for some time, a series of earth-movements 

 were set up, by which "these beds with the underlying rocks were 

 thrown into ridges and troughs by two sets of folds more or less at 

 right angles to each other, the axes of the one lying S.W.-N.E., and 

 the other N.W.-S.E. These folds gave rise to shallow basins by 

 their interference with each other, and it was in these that the 

 Lower Miocene beds Avere deposited, after the outpouring of the 

 basalt lavas, and the thermal springs which followed the dying out 

 of the volcanoes had ceased. Between the deposition of the Gebel 

 Ahmar Sands and the transgression of the first Mediterranean sea, 

 there was another continental period during which these sands were 

 <lenuded to a certain extent. After the Lower Miocene sea had 

 invaded this area and was depositing its sediments, what more 



