to a date earlier than
that at which our ingenuous youth is instructed that the earth came into
existence. For, the alluvial deposit having been brought down by the
rivers, they must needs be older than the plain it forms, as navvies
must needs antecede the embankment painfully built up by the contents of
their wheel-barrows. For thousands of years, heat and cold, rain, snow,
and frost, the scrubbing of glaciers, and the scouring of torrents laden
with sand and gravel, have been wearing down the rocks of the upper
basins of the rivers, over an area of many thousand square miles; and
these materials, ground to fine powder in the course of their long
journey, have slowly 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