Page:Popular Science Monthly Volume 23.djvu/348

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Similar accumulations of fossil wood occur on the western side of the delta, about the Natron Lakes and in the Bahr-bela-Ma.

All these trunks have weathered out of a miocene sandstone; and it has been suggested that, when this sandstone was deposited, the Nile brought down great masses of timber from the upper country, just as the Mississippi sweeps down its "rafts" into the Gulf of Mexico at the present day; and that a portion of these, after long exposure and knocking about in the flood, became silted up in the sandy shores of the estuary.

The greater part of the "petrified forest" is at present one thousand feet above the level of the sea, in the midst of the heights which form the eastward continuation of the Mokattam. It has, therefore, shared in the general elevation of the land which took place after the beginning of the miocene epoch. That such elevation occurred is proved by the fact that the marine beds of that period lie upon the upraised limestone plateau of Lower Egypt; and it must have reached seven or eight hundred feet, before the Pholades bored the rocky shore of the gulf of the delta.

A flood of light would be thrown on the unwritten history of Egypt by a well-directed and careful re-examination of several points, to some of which I have directed your attention. For example, a single line of borings carried across the middle of the delta down to the solid rock, with a careful record of what is found at successive depths; a fairly exact survey of the petrified forest, and of the regions in which traces of the ancient miocene sea-shore occur; a survey of the Selsileh region, with a determination of the heights of the alluvial terraces between this point and Semneh; and an examination of the contents of the natural caves which are said to occur in the limestone rocks about Cairo and elsewhere—would certainly yield results of great importance. And it is to be hoped that, before our occupation of the country comes to an end, some of the many competent engineer officers in our army will turn their attention to these matters.

But, although so many details are still vague and indeterminate, the broad facts of the unwritten history of Egypt are clear enough. The Gulf of Herodotus unquestionably existed and has been filled up in the way he suggested, but at a time so long antecedent to the farthest date to which he permitted his imagination to carry him, that, in relation to it, the historical period, even of Egypt, sinks into insignificance.

However, we moderns need not stop at the time when the delta was a gulf of the sea. The limestone rocks in which it is excavated and which extend east, west, and south for hundreds of miles, are full of the remains of marine animals, and belong, the latest to the eocene, the oldest to the cretaceous formation. The miocene gulf of the delta was, in fact, only the remains of the wide ocean which formerly extended from Hindostan to Morocco; and at the bottom of which the