growth, and beneficial in operation. No lakes are interposed
between the mountain torrents of the upper basis of the Tigris
and the Euphrates and their lower courses. Hence, heavy rain, or
an unusually rapid thaw in the uplands, gives rise to the sudden
irruption of a vast volume of water which not even the rapid
Tigris, still less its more sluggish companion, can carry off in
time to prevent violent and dangerous overflows. Without an
elaborate system of canalisation, providing an escape for such
sudden excesses of the supply of water, the annual floods of the
Euphrates, and especially of the Tigris, must always be attended
with risk, and often prove harmful.

There are other peculiarities of the Euphrates valley which may
occasionally tend to exacerbate the evils attendant on the
inundations. It is very subject to seismic disturbances; and the
ordinary consequences of a sharp earthquake shock might be
seriously complicated by its effect on a broad sheet of water.
Moreover the Indian Ocean lies within the region of typhoons;
and if, at the height of an inundation, a hurricane from the
south-east swept up the Persian Gulf, driving its shallow waters
upon the delta and damming back the outflow, perhaps for
hundreds of miles up-stream, a diluvial catastrophe, fairly up
to the mark of Hasisadra's, might easily result.<2>

Thus there seems to be no valid reason for rejecting Hasisadra's
story on physical grounds. I do not gather from the narrative
that the "mountains of Nizir" were supposed to be submerged, but
merely that they came into view above the distant horizon of the
waters, as the vessel drove in that direction. Certainly the
ship is not supposed to ground on any of their higher summits,