90 DE. GRANT BEY, 



again the sea bottom ; the alluvium was all washed away 

 leaving only sand, and fallen deeaying trees, water-logged 

 in a silicitied sea, Avhich was rendered all the more silicious 

 by the presence in it of geysers. As the sea cooled down, 

 the trees became silicified, and lay like rocks embedded in 

 the sand at the bottom of the sea ; while in the immediate 

 vicinity of the geysers themselves, the loose sand became 

 solidified into a heterogeneous mass, containing many of the 

 silicified trees in the lowest part of its structure.* Some of 

 the trees are palms, showing that Egypt continued to have 

 a tropical climate similar to that of the Soudan in our time. 

 This new stratum formed what is called the Miocene, and 

 when it in turn was upheaved and became dry land, all its 

 loose sand was gradually blown away, leaving the Eocene 

 towering up at places to the height of 600 feet, as the 

 Mokattam range at Cairo, while the petrified trees were 

 exposed, lying on the svu-face of the Eocene. Of course, 

 where the sand itself was glued together by silica, it 

 remained as a sandstone hill, such as " Gebel Ahmar " near 

 Cairo, where traces of two geysers may still be seen, with 

 petrified wood embedded in its lower stratum ; thus showing, 

 as if it were written on the pages of a book, the exact 

 position in geological history to Avhich these petrified trees 

 belong, and the climatic conditions of that period when 

 these natural forests existed.^ The areas of marine Pliocene 

 hoAv^ever in p]gypt are rare, indicating that this region had 

 already assumed in a great measure a continental character. 



According to Sir J. Wm. Dawson at the close of the Eocene 

 Period the Gulf of Akabah, which had been, up till then, in 

 communication with the Mediterranean, was closed, but the 

 Gulf of Suez continued to be a Strait ; and the Mediterranean, 

 Avhich washed the base of the Mokattam range, extended 

 even to the east oi Gebel Attaka on the Red Sea. This 

 remained so through tlie Miocene Period, so that there was 

 free communication between the Red Sea and Mediterranean 

 and the disconnection could scarcely have taken place till the 

 first continental period of the Pliocene, Avhen the Blue Kile 

 lost itself in a lagoon of the isthmus on the Red Sea side, 

 and contributed considerably to the enlargement of that 

 isthmus. 



This was the first separation of the waters of the Red Sea 

 and Mediterranean in geological history. 



The climate Avas then a little Avarmer than noAV as may 

 be gathered from the shells and animal remains of the 



