August 18, 1996
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There are those places in the world where both man and nature are driven to extremes, and are therefore forced to yield up certain truths that otherwise might remain hidden. For as Francis Bacon once said, "you have but to follow and as it were hound nature in her wanderings, and you will be able, when you like, to lead and drive her afterwards to the same place again." Such a place is the Dead Sea. In 1972 a prominent California engineer named Tom Leps, knowing of research work I had published on the invisible but calculable flow of groundwater, approached me with the assignment of determining the manner of movement of water beneath the bottom of the south end of the Dead Sea, not far from the town of Sodom (or Sedom, as it is sometimes called.) It happened that the government of Israel had contracted with the California firm of Kaiser Engineers (then basking in public gratitude for its ship-building efforts in the war) to build some dikes within which they aimed to capture, concentrate, and dry out valuable salts for which that ancient body of water is so famous. I did not know it at the time but the digging of potash in that grim setting is an enterprise into which many past fortunes had sunk without a trace, it having been long said among shrewd investors that "nothing can sink in the Dead Sea but money." It is therefore no surprise that on completion of this latest construction project it was seen that the dikes quickly failed, the water soon leaking beneath them. This fiasco led to a lawsuit at the International Court at The Hague. Leps, who had once worked with the great the famous dam engineer Karl Terzaghi, was retained as an expert on the case.
My consulting assignment was successfully completed when the results of this early effort at groundwater modelling -- I used an electrical analogue of the D'Arcy equations which I had developed as a graduate student at London -- showed that the failure of the Dead Sea dikes was an inevitable design defect (the feasibility of building water tight dikes on soluble material such as salt has to be relearned every few years, as we have subsequently seen in various more recent failures of dams built on salt beds). The failure had arisen in layers of cracked and soluble salt that had accumulated sporadically on the floor of the sea over the millennia. The levees themselves, which had been provided with a central slurry-wall core aimed to prevent seepage, had not failed; their foundations had.
Footnotes
[1]
It was not of course the first time that outlandish
things have happened in this land of salt, wet heat, and
earthquake faults; for here we have the closest place to
hell, land of extremes of both nature and human
behavior, of mad saints and zealous outcasts. Lot had
settled there, when the land was said to be lush and
fertile. The destruction of Sodom and Gomorrah was
already an old story when it had been written into the Bible
three thousand years ago. The chronicler Josephus
claimed to have seen with his own eyes there the seared
and salted remains of Mrs. Lot in the first century;
seventeen hundred years later Josephus' translator
William Whiston impatiently waited the day when the
quarrels of local desert princes would subside so that
properly scientific studies of these biblical events
could be undertaken. Captured by the Arabs in the 1948
war, the remote town had been retaken only to become a
disreputable center of drugs and prostitution when the
salt works were reopened. The place had long yielded
fertile crops of stories; the mystery play History of
Lot and Abraham had thrilled the medievals and only a
few months ago a colleague of mine, Amos Nur, had
announced that the famous biblical fire and brimstone had been
produced by an earthquake in that same place in 1900 BC. So we have
in this strange land a
continuing entanglement of geophysics and morals.
[1]
[2]
Perhaps more interesting for present purposes than these
engineering matters was the odd character of the sea
bottom which was composed of salt and marly silt layers
that could be "read" as a chronology of past climates,
of the wet and dry spells that had come and gone with
the rest of the desert wanderers over thousands of
years. It occurred to me that there may been something
to the biblical story description of the place as a land
of fertility and delight when Lot had first arrived
there (Genesis 13)
Such an abrupt local climatic shift
was not entirely implausible, given perhaps a radical
northward migration of the Saharan monsoon system.
Some
time in the late seventies I read of the discovery of
bits and pieces of vegetable matter discovered in caves
along with the famous Dead Sea Scrolls. These twigs would
have their own story that would be revealed with the
advent of radiocarbon dating in the 1950s.
But it would be twenty years before I discovered the
facts and circumstances are as follows.
Not far from the southern end of the Dead Sea is an odd
formation of flat-topped salt bluffs -- a diaper in
geological terms -- several miles in extent and a
thousand or so feet high. The formation is known as
Mount Sedom, after the ancient place. Prominently
exhibited on a rise above the stinking sea is the a salt
spire said to be Lot's wife. The area, being most
inhospitable, is not often visited; according to the
Lonely Planet and Let's Go travel guides the
115 degree walk from the bus stop past the "Mrs. Lot"
salt pillar, back up into the hills some several
kilometers to the great Malham Cave, is enough to make
even the resilient readers of those publications feel
as dead as the sea that glitters with dull malevolence
in the haze below.
It happens that the caves at the 300 foot level are not
only the widest of many that perforate the salt hills
but also contain, preserved over the millennia, twigs
and leaves of Quercus Calliprinus. These can
hardly be assumed to be of local origin considering that
the area is salt, not soil, within a searing desert with
an annual rainfall of less than two inches, hardly
enough to moisten the parched ground much less support
oaks. Now it is geologically certain that it was an
ancient pluvial age that created caves in the salt; in
fact past climate can be inferred by carefully measuring
the width of caves formed by salt dissolution. The cavewidths can in
turn be compared with correlative glacial
advances in northern Europe (bigger caves = more rain =
more glaciers) and the cave elevations with ancient sea
levels of the Dead Sea itself. The horizon of wide caves
found some 300 feet above the present sea level
necessarily indicates an extremely wet period in the
early Bronze Age, or about 4200 to 5200 radiocarbon
years before present. Oak twigs, driftwood, and marl
found in the caves must have been transported by
floodwater from some other part of the Judiah Hills.
when the water level was some 300 feet higher than
present, implying heavy flooding on the Jordan River and
coupled probably with lower evaporation rates due to
cooler weather. These strands of evidence have been
carefully pieced together by Israeli scientists, whose
conclusions are indicated graphically in terms of level
of the Dead Sea in the figure.
Prominently shown is the fact that the land in the great
rift valley was wet and the Dead Sea level high up until
about 7000 years ago. This conclusion is in agreement
with other paleoclimatic information, it being well
established that North Africa was lushly tropical in the
early Holocene period. Around 7000 years ago the land
became drier, much as it is today.
Of greatest relevance here is the is the great hump in
the curve that came later, centering on 3000 BC; no
other event following the great drying 7000 years ago
quite matches this spectacular 300 foot rise in sea
level. When exactly did this occur? Radiocarbon dating
of both the oaks twigs and the marl show a peak at 4350
radiocarbon years before the present. Clearly there had
been a time of great flood in North Africa just before
3000 BC.
The evidence suggests a great flood, corresponding no
doubt to a radical arrangement of pastoral or civil
life, followed by destruction, dessication, and salting
of the earth.
On these events it appears that the bible and the oaks
speak in one voice.
[3]
Frumkin, Amos (University of Jerusalem, Israel Cave
Research Center, Jerusalem) Holocene climatic record of
the salt caves of Mt. Sodom, Israel, 1991 The Holocene;
vol 1, no. 3, p 191-200.
The many stories of this land including the rediscovery
of Masada and of the Dead Sea scrolls are skillfully
recounted in Barbara Kreiger's fine historio-travelogue,
Living Waters, Myth, History, and Politics of the Dead
Sea.
For a nice site on the Dead Sea Scrolls, see >>Dead
Sea Scrolls
[3]
See Late Quaternary
Chronology and Paleoclimates of the Eastern Mediterranean edited by Ofer
Bae-Yosef and Renee S. Kra, published by RADIOCARBON, Univ Arizona, 1994. For
grass pollen and oak indicators of Holocene summer rains in the Arabo-Persian Gulf,
see El-Moslimany; for early bronze age
wet periods, notable the spectacular rise in the Dea Sea at 4500 c14 years bp,
see Frumkin and Bruins. See also Chronicle of the Late
Holocene
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