UNWRITTEN HISTORY. 333 



Herodotus for the filling up of the Arabian Gulf twenty thousand 

 years is very much below the time required for the formation of the 

 delta. 



Thus far we have traced the unwritten history of Egypt, and the 

 gulf of the Mediterranean, postulated by Herodotus, is not yet in 

 sight. Nevertheless, at a much more remote epoch in that called 

 miocene by geologists the gulf was assuredly there. 



Near the tombs of the Caliphs at Cairo (according to Schwein- 

 furth, two hundred feet above the level of the Mediterranean), in the 

 neighborhood of Sakkarah and in that of the great pyramids, the lime- 

 stone rocks, which look so like a sea-shore, were found by Professor 

 Fraas to display the remains of a veritable coast-line. For they ex- 

 hibit the tunnels of boring marine mollusks [Pholades and Saxicavce), 

 and they are incrusted with acorn-shells, as if the surf had only lately 

 ceased to wash them. At the feet of these former sea-cliffs lie ancient 

 sandy beaches, containing shells of oysters, scallops, and other marine 

 mollusks, with the skeletons of sea-urchins. The specific characters of 

 these marine organic remains leave no doubt that they lived during 

 the miocene, or middle tertiary, epoch. Marine beds of the same age 

 occur at Ain Musa, between Cairo and Suez. 



There can be no question, therefore, that, in the miocene epoch, the 

 valley of the delta was, as Herodotus thought it must have been, a 

 gulf of the sea. And, as no trace of marine deposits of this, or of a 

 later age, has been discovered in Upper Egypt, it must be assumed 

 that the apex of the delta coincides with the southern limit of the 

 ancient gulf. 



Moreover, there is some curious evidence in favor of the belief 

 that, at this period, however remote as measured by our standards of 

 time, the Nile flowed down from Central Africa as it flows now, but 

 probably in much larger volume. Every visitor to Cairo makes a pil- 

 grimage to the " petrified forest," which is to be seen in the desert a 

 few miles to the northeast of that city. And indeed it is a spectacle 

 worth seeing. Thousands of trunks of silicified trees, some of them 

 twenty or thirty feet long, and a foot or two in diameter, lie scat- 

 tered about and partly imbedded in the sandy soil. Not a trunk has 

 branches, or roots, or a trace of bark. None are upright. The struc- 

 ture of wood, which has not had time to decay before silicification, is 

 usually preserved in its minutest details. The structure of these 

 trunks is often obscure, as if they had decayed before silicification ; 

 and they are often penetrated, like other decayed wood, by fungi, 

 which, along with the rest, have been silicified.* 



* See Unger, " Der versteinerte Wald bei Cairo," " Sitzungsberichte der Wiener 

 Akademie," 1858. Dr. Schweinfurth ("Zur Beleuchtung der Fra?e ueber den verstein- 

 erten Wald," "Zeitschrift der deutschen geologischen Gesellschaft," 1882) considers that 

 the trees grew where they are found, but his arguments do not appear to me to be con- 

 vincing. 



