Visitors to the Dead Sea, the lowest place on earth - it is 395 meters below sea level (1,296 feet) - may not experience the same sense of achievement as those who climb to the summit of the world - Mount Everest - but the stark, almost lunar, environs of the Dead Sea and the echoes of human history from past eons evoke, nevertheless, a sense of awe and fascination.
Despite its name, the Dead Sea is not totally inert; under the influence of the atmosphere, fluctuations in temperature, evaporation, the flow of incoming water and, to an extent, human activity, it is in a state of chemical and geological flux.
The Dead Sea, which lies along a geosuture (a sunken block between two geological faults), was formed when the land subsided and filled, some 10 million years ago, with water. This turned the entire Jordan Valley region into a continuous body of water - a large inland lake called Lake Lisan (lisan meaning "tongue" in Arabic). Later, the lake began to dry up and shrink, eventually breaking up into Lake Tiberius and the Dead Sea.
Because the Dead Sea, originally spring-fed, lies in a basin with no exit, salts have accumulated in the basin, sometimes by percolation through the surrounding earth. Gradually building up over the centuries, they give the Dead Sea its strongly saline character: higher concentrations of salts than any other large body of water. These salts include magnesium, potassium and bromide - which comprise about 13 percent of the ionic composition of the surface water and are largely responsible for the bitter taste and "greasy" feel of the water.
One result of this odd chemistry is the striking, but transient, salt crystal formations. Appearing-unexpectedly - in shallow lagoons at periodic intervals, these formations are natural works of art: billions of charged atoms in intricate geometrical formations shaped by nature into unique works of crystalline art.
The most impressive of these natural sculptures are the "salt mushrooms" which stand on their halite or rock salt stems in shallow pools near the shoreline. Their hoods are circular to elliptical and the mushroom cap can reach up to half a meter in diameter (20 inches). From afar they look like giant fungi sprouting from the water but closer inspection shows concentric rings of small, platy rectangular halite crystals with patchy crusts seated on hollow stalagmitic stems composed of what are called "pyramidical" crystals.
While many of the formations have clearly defined stems and caps, some of the "mushrooms" are less distinct; the two sections meld into inverted pyramidical shapes protruding from the water. Others, with no cap at all, give the impression that weathered columns from some submerged Roman city are surfacing from the depths of the sea.
Since the rates of formation for each mushroom vary, various stages of growth are evident in most of the formations; it looks as if an animal has wandered through the field nibbling at the fungi. And although not as striking as the finished article, the formative stages of the salt mushrooms are impressive in their own right and further emphasize the ephemeral quality of the Dead Sea's character. Mushrooms usually begin to form on cool mornings, after periods of intense evaporation when the shallow lagoons become covered with floating rectangular halite crystals. The crystals blanket the surface of the water with an opaque, exceptionally delicate coating; the most gentle breeze can break this sheet and when it breaks, parts of it sink and the crystals attach themselves to plant debris or pebbles. Gradually, as a result, a stem of halite crystals begins to grow upwards, eventually reaching the surface where other crystals adhere to it and form the cap.
Each stage of the process is delicate; a strong gust of wind, sudden rainfall, a rush of incoming water or temperature fluctuations can halt and destroy the stem. In the space of a day, in the salt sculpture may totally disappear beneath the water.
Because the ions and isotopes present in the water of the Dead Sea crystallize in different ways, there is a diverse array of natural formations. Hard, light-gray-to-brownish crusts of gypsum (hydrated calcium sulphate) can be seen on the keels of boats, on rocks, and on ropes left hanging in the water. The comparatively large, flat polygonal plates in gypsum crystals give rise to more crusty structures than those formed by clusters of calcite (crystalline calcium carbonate) which has crystals resembling small twinned needles; these needles lock together in forms resembling blossoms of white anemones. Along the shores of the Dead Sea variations in the forms depend on how ions are arranged within the structure and whether other ions or trace elements find their way into the lattice to substitute for particles with the same charge.
Even mundane aragonite (calcium carbonate), a common compound found in chalk and limestone, can take on a spectacular appearance when an increase in temperature, often at the end of summer, triggers mass precipitation; the result is a dramatic whitening of the water as snowy clouds of the compound slowly descend to the sea bed. Turbulence and wave motion prolong the deposition of aragonite and give the water a striking, nebulous quality.
On other occasions, the Dead Sea wears a different mantle: sheets of air bubbles foam like surf on the ocean; the froth is probably formed from the contact of hot or cold springs with the waters of the Dead Sea and is due to differences in temperature and density.
Although not particularly attractive, chips of asphalt also decorate the Dead Sea and evoke images of the past. For example, there is an episode in Genesis, chapter 14.2 and 3, in which the kings of five cities - Sodom, Gomorrah, Admah, Zeboiim and Bela (which is Zoar) - were defeated in battle and, while fleeing, fell into what seem to have been bitumen pits "in the Vale of Siddim which is the Salt Sea."
Since floating asphalt is only found after storms, wave activity probably dislodges it from the bottom; research, moreover, has indicated that seepages occur not deeper than 15 to 30 meters beneath the present lake level (49 to 98 feet) so they could be identified with the bitumen pits mentioned in the Bible. In addition, it is popularly believed that the cities of Sodom and Gomorrah, destroyed by fire and brimstone, are lost in the depths of the Dead Sea.
Today, the character of the Dead Sea is slowly changing and with the passage of time fewer of these natural formations and phenomena of the sea will remain. This is because the salty waters of the famous sea are gradually drying up as increasing amounts of water are drawn off from the streams and rivers flowing into the lake and used in agriculture, mining and industry. Already the evaporation rate exceeds the inflow rate and eventually the whole area will become mud flats. If political boundaries did not exist, in fact, it would soon be feasible to cross the Dead Sea at its narrowest point - the Lisan Strait - just as 19th - century camel caravans did. Already large halite crystals - cubes with up to 10-centimeter faces - can be picked up from areas exposed after periods of high evaporation.
Tourists, who generally come to the Dead Sea to experience its unique buoyancy and to have their photograph taken reading a newspaper while floating, are surprised and impressed when they chance upon such striking crystal formations; such phenomena are rarely mentioned in guidebooks and are seldom included as part of the Dead Sea's attractions because they are not in the area adjacent to the main tourist beach and facilities. And they may never be mentioned. Although scientists believe that it could take 1,000 years for the Dead Sea to dry up completely, many of the salt formations are already beginning to disappear - another facet of the ancient Middle East vanishing beneath the sands.
Anne Counsell, an editor with the Jordan Times, has a degree in agriculture and environmental science. She has contributed articles to the Financial Times and International Herald Tribune.