It was, as I have said, the primitive seaport of Babylonia, and its legend of the first man Adamu made him a fisherman in the Persian Gulf. Its site is now rather more than a hundred miles distant from the present line of coast. The progress of alluvial deposit brought down by the Euphrates and Tigris can be estimated by the fact that forty-seven miles of it have been formed since Spasinus Charax, the modern Mohammerah, was built in the age of Alexander the Great, and was for a time the port of Chaldæa. During the last 2000 years, accordingly, the rate of deposit would seem to have been about 115 feet a year. This, however, does not agree with the observations of Loftus, who made the rate not more than a mile in every seventy years,[76] while on the other hand Sir Henry Rawlinson adduced reasons for believing it to have been more rapid in the past than it is to-day, and that consequently the rate must once have been as much as a mile in thirty years.[77] It is desirable that some competent geologist should study the question on the spot. Taking, however, as a basis of calculation, the one known fact of the rate of growth since the foundation of Spasinus Charax, and bearing in mind that before the junction of the Tigris and Euphrates the rate of advance must have been comparatively slow, we should have to go back to about B.C. 5000 as the latest date at which Eridu could still have been the seaport of the country. Was it here that the system of writing which was so closely entwined with the origin of Babylonian civilization was first invented? Babylonian tradition in later days certainly believed that such was the case, and the fact that Ea of Eridu was the culture-god of Babylonia is strongly in its favour. But there are difficulties in the way. Eridu was the home of the “white witchcraft” of early Chaldæa; it was here that the charms and incantations were composed which gave the priesthood of Eridu its influence, and made the god they worshipped the impersonation of wisdom. The belief that he was the originator of Babylonian culture may have had its source in the system of magic which was associated with his name. Eridu was built on the Semitic side of the Euphrates, and the Semitic tribes who received their letters and their civilization from the Sumerians of Eridu would naturally have looked upon the city of their teachers as the primeval home of Sumerian culture. The traditions that made Eridu the starting-point of Sumerian civilization could thus be explained away, and we should be left free to settle the question of its origin upon purely archæological evidence.