subsided, as the water which carried them spread out and lost
its velocity in the sea. It is because this process is still
going on that the shore of the delta constantly encroaches on
the head of the gulf<5> into which the two rivers are constantly
throwing the waste of Armenia and of Kurdistan. Hence, as might
be expected, fluviatile and marine shells are common in the
alluvial deposit; and Loftus found strata, containing subfossil
marine shells of species now living, in the Persian Gulf, at
Warka, two hundred miles in a straight line from the shore of
the delta.<6> It follows that, if a trustworthy estimate of the
average rate of growth of the alluvial can be formed, the lowest
limit (by no means the highest limit) of age of the rivers can
be determined. All such estimates are beset with sources of
error of very various kinds; and the best of them can only be
regarded as approximations to the truth. But I think it will be
quite safe to assume a maximum rate of growth of four miles in a
century for the lower half of the alluvial plain.

Now, the cycle of narratives of which Hasisadra's adventure
forms a part contains allusions not only to Surippak, the exact
position of which is doubtful, but to other cities, such as
Erech. The vast ruins at the present village of Warka have been
carefully explored and determined to be all that remains of that
once great and flourishing city, "Erech the lofty."
Supposing that the two hundred miles of alluvial country, which
separates them from the head of the Persian Gulf at present,
have been deposited at the very high rate of four miles in a
century, it will follow that 4000 years ago, or about the year
2100 B.C., the city of Erech still lay forty miles inland.
Indeed, the city might have been built a thousand years earlier.