'Pvof. J. W. Dan-son — Notes on the Geology of Egypt. 387 



Seneffeh, north of Suez, Fraas has found similar beds, but which 

 do not appear to be very extensive in their distribution. I had no 

 o]3portunity to study these formations, but their chief point of interest 



jtBtL /^'-'M^f? 



/ U. EOCENE 



M.iEOCEWE 



Fig. 1. — Relation of the Miocene Sandstone of Jebel Ahmar to the Eocene of the 



base of the Mokattam Hill, (x x) Supposed Geyser pipes. 



(+) Here row of fossil trees. 



appears to lie in the fact that they occupy low grounds resulting 

 from the partial removal of the Eocene, which seems to have ex- 

 perienced both elevation and marine denudation before they were 

 deposited. These Miocene beds have sometimes been confounded 

 with the raised beaches and terraces holding Ostrea Forskali, and 

 with the Clijpeaster sands near Gizeh, but these, as already stated, 

 are probably considerably newer. 



Another deposit, also newer than the Miocene, is that which 

 occupies the highest part of the Isthmus of Suez, immediately north 

 of Ismalia, and which has been described by Fraas and Le Vaillant.^ 

 Though occupying a narrow space at the Isthmus, these deposits 

 extend to a considerable distance east and west, and as they are 

 overlain at both sides of the Isthmus by more modern beds, may 

 be of greater breadth than appears at the surface. 



As they occur near Ismalia, and in the cuttings on the canal 

 between that place and El Gisr, they consist of thin-bedded grey 

 limestones with vermicular holes, in horizontal beds, and resting 

 on marls, sands and clays with gypsum and nodules of chalcedony. 

 The greater part of these beds are destitute of fossils ; but in, or 

 associated with, the series, there are layers holding freshwater shells, 

 more especially JEtlieria Caillaudi, Ferussac, a species now confined 

 to the IJpper Nile. This species has been found by Le Vaillant 

 as far south as the cutting on the Suez Canal at Shaluf el Terraba, 

 and it also occurs north of Ismalia. This formation would seem to 

 imply the discharge of the Nile or a considerable branch of it to the 

 eastward, and this not into a marine estuary, but into a saline lake, 

 or a lake at some times salt and at others fresh. The greater part 

 of these deposits indeed greatly resemble those occurring in the 

 elevated terraces of the Dead Sea. The deposition of these beds 

 would also seem to have occurred at a time of continental elevation, 

 when the isthmus was represented by a wide extent of land, and 

 during the prevalence of a warm climate. 



The date of these deposits must be placed between the Miocene 

 period and the modern Ked Sea and Mediterranean marine dej^osits 

 which flank the isthmus on the south and north. But within these 

 limits, we have two continental periods to decide between — that 



^ Aus dem Orient, Bui. Geol. Soc. of France vol. sxii. 186S. 



