The same theory may, as Colonel Emy observes in his remarkable work, throw a new light on important geological facts:— “For instance, those ancient and elevated plains, composed of sand and pebbles, the formation of which, it has been attempted to explain, by the revolutions of the globe and violent convulsions of nature, or which have been regarded as deposits left by rivers, appear to be maritime accretions. If is, indeed, easy to conceive rivers capable of bringing down the fragments detached from mountains, by shocks, and by the decomposition of the rocks; but how could they extend those fragments uniformly, and over spaces so extensive as the plains in question? Moreover, was not the course from the summits of the mountains generally too short for the fragments of the excessively hard rock found in some of those plains, to have time to acquire their roundness? The rivers have prolonged their courses through these accumulations of pebbles; they may, in overflowing, have covered them with sand and earth, but it is more probable that they contributed in nowise to the formation of these accretions, unless it were by transporting the rough materials to the sea. Nothing but the ground swell could spread these fragments of mountains so uniformly as they are, convert them into shingle and sand by a long trituration on the shores, where it had driven them; gather them either into banks or plains, and thus fill up spaces over which the sea formerly extended. “The ancient collections of shingle, pebbles and sand are owing, like those at present forming in a similar manner, to maritime accretions, and must henceforth be regarded as an incontestable proof that the ocean formerly reached and was long stationary at different heights far exceeding its present level.” It is not surprising, then, to find on divers points of the Isthmus pieces of hard stone broken into small fragments, and half rounded, covering the sand-banks at variable heights above the level of the Mediterranean. But, be it as it may, it is certain that throughout the length of the line, from the roadstead of Suez to that of Pelusium, the excavations will only be in light earth, which can be easily removed by hand as far as the water line, and with dredges down to the bed of the Canal. The track which we have followed for the Canal was prescribed by the very nature of the locality, and by the condition that the two Seas were to be brought into direct communication in the most economical manner.