4 o8 SCIENCE PROGRESS. 



lamellibranchs, and other fossils. These beds are all marine ; 

 but south of the oasis, in places resting conformably upon 

 the marine beds, are sandstones and fresh-water limestones 

 with Pkysa, Planorbis, and Limnaea. 



Marine beds containing a similar fauna occupy the 

 greater part of the valleys between Jebel Geneffeh and 

 Jebel Attaka, and between Jebel Attaka and the Northern 

 Galala (5). Fuchs, after a comparison of the fossils from 

 Jebel Geneffeh and from Siwa, has come to the conclusion 

 that they are of an age intermediate between the first and 

 second Mediterranean stages. 



Pliocene and recent. — Since the Miocene period the 

 Egyptian area seems to have been subject to comparatively 

 little disturbance ; but there has been a gradual elevation of 

 the whole region. At the foot of the Mokattam Hill at 

 Cairo marine sands are found banked up against a vertical 

 cliff of Eocene rocks, which is itself bored by Lithodomus 

 or similar shells (ii, 9, etc.). The upper limit of the 

 borings is some 200 feet above the level of the Mediter- 

 ranean, indicating a rise of land of at least that extent. 



Near the pyramids of Giza there is a sand which is 

 characterised especially by the well-known fossil Clypeaster 

 cegyptiacus or pliocenicus. In the Wadi el Mellaha, some 

 four miles south of the great pyramids there is another bank 

 of sand and sandstone, containing a number of shells of the 

 genera Strombus, Cassis, Conns, etc. According to Mayer- 

 Eymar it is clear that both these deposits lie on the same 

 ofeolomcal horizon, and from the character of the fauna in 

 the latter he refers them both to the "diluvial" period (17). 

 Neumayr, however, has since shown that they are Pliocene 



(20). 



Still more recent probably than these are the deposits 

 which form the isthmus of Suez. They have been described 

 by Fuchs (12), who comes to the conclusion that, in spite oi 

 the great difference between the faunas of the Red Sea and 

 of the Mediterranean, there was a connection between the 

 two seas until at least Pliocene times. He finds nothing 

 but Pliocene or later deposits between Port Said and Suez. 

 Recent deposits with a Mediterranean fauna extend south- 



