sea. Lake Mariut, close to Alexandria, has a circumference of at least 60 miles, and the steep cliffs towards the south and west give it the aspect of a true lake. Yet it was completely dry in 1799, when the English cut the embankment separating it from the sea. Since then it is once more diminishing, the breach having again been repaired. Whether the ancient Egyptians had also drained it by cutting off its seaward communications, or whether the mainland was then
Scale 1: 860,000.
more elevated than at present, Mareotis was certainly either altogether or partly dry at some remote epoch, for in its bed remains are found of old temples and statues.
If it is difficult to estimate the encroachments of the Nile delta on the sea and the surrounding lakes, an equally intricate problem is presented by the gradual upheaval of the whole region subject to the annual inundations, for here account must also be taken of the sands brought by the wind, as well as of the sediment deposited by the stream. From the comparative observations made during the French expedition, Girard calculated that by the Nile alluvia the soil was raised on an average about 5 inches in a century. Hence, notwithstanding its slight encroachments seawards, the level of the delta would have been raised about 20 feet during the last five thousand years, that is, since the Egyptians had already
