valley really was once filled with
water, the surface of which reached within 160 feet of the level of the
pass of Jezrael, and possibly stood higher, is this: Remains of alluvial
strata, containing shells of the freshwater mollusks which still inhabit
the valley, worn down into terraces by waves which long rippled at the
same level, and furrowed by the channels excavated by modern rainfalls,
have been found at the former height; and they are repeated, at
intervals, lower down, until the Ghor, or plain of the Jordan, itself
an alluvial deposit, is reached. These strata attain a considerable
thickness; and they indicate that the epoch at which the freshwater mere
of Palestine reached its highest level is extremely remote; that its
diminution has taken place very slowly, and with periods of rest,
during which the first formed deposits were cut down into terraces. This
conclusion is strikingly borne out by other facts. A volcanic region
stretches from Galilee to Gilead and the Hauran, on each side of the
northern end of the valley. Some of the streams of basaltic lava which
have been thrown out from its craters and clefts in times of which
history has no record, have run athwart the course of the Jordan
itself, or of that of some of its tributary streams. The lava streams,
therefore, must be of later date than the depressions they fill. And
yet, where they have thus temporarily dammed the Jordan and the Jermuk,
these streams have had time to cut through the hard basalts and lay bare
the beds, over which, before the lava streams invaded them, they flowed.

In fact, the antiquity of the present Jordan-Arabah valley, as a hollow
in a tableland, out of reach of the sea, and troubled by no diluvial
or other disturbances, beyond the volcanic eruptions of Gilead and of
Galilee, is vast, even as estimated by a geological standard. No marine
deposits of later than miocene age occur in or about it; and there is
every reason to believe that the Syro-Arabian plateau has been dry land,
throughout the pliocene and later epochs, down to the present time.
Raised beaches, containing recent shells, on the Levantine shores of
the Mediterranean and on those of the Red Sea, testify to a geologically
recent change of the sea level to the extent of 250 or 300 feet,
probably produced by the slow elevation of the land; and, as I have
already remarked, the alluvial plain of the Euphrates and Tigris appears
to have been affected in the same way, thou