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The Dead Sea basin itselfis divided into two sub-basins (Figure 2): the South-
ern subareal sub-basin occupied by commercial evaporation ponds and the northern
sub-basm occupied by a ~300-m-deep lake. The sub-bottom structure of the basin
is composed of a deep depression. Seismic refraction data indicate that the depth to
the basement in the Southern part of the basin is more than 10 kilometers. It is over-
laid by a large sequence of Sediments that reaches the surface. When taking in
account the height of the Judea Mountains on the west and the Moab Mountains
on the east and the erosion that took place in this region, the Dead Sea basin is one
of the deepest “cracks” in the Earth’s crust, over 13 km.
Several lakes were developed in tectonic depressions along the Dead Sea
basin-Jordan Valley in the last several milhon years.The series of lakes in the Dead
Sea region disappeared and reappeared over a long period due to chmatic and geo-
logical changes in the area. The last of these lakes, known as Lake Lisan, stretched
from the northern Arava Valley, south of the Dead Sea, to the Sea of Gahlee. About
15,000 years ago it dried up, leaving behind what is known now as the Dead Sea.
Climatic changes have caused considerable fluctuation in the level of the lake’s
water. Sediments, which were deposited in the Dead Sea and previous lakes, record
the climatic conditions that prevailed in the region during the Pleistocene-
Holocene time. These Sediments are quite sensitive to the water level during the
time of deposition.
The extreme negative elevation in combination with the tectonically elevated
mountains that flank the basin promotes a very arid environment marked by low
precipitation and high evaporation. Water that enters the Dead Sea has no outlet in
this actively subsiding basin.These conditions control the physical, chemical and bio-
logical properties of the inland lake. The hypersalme Dead Sea water is dense with
more than 30 % dissolved solids, the highest salimty of any lake on Earth. The dis-
solved material mcludes high concentrations of potassium, bromine and magnesium
salts, which are commercially exploited. These salts apparently constitute Israel and
Jordans most extensive natural resource.
Almost nothing can survive in this water except highly specialized halophilic
green algae and red archaeobacteria, which are of great scientific interest.The Dead
Sea water composition differs from other sahne lakes in lts high concentration of
magnesium and calcium. As a result, unique highly specialized endogenous commu-
nities of microorganisms are able to endure the hypersaline, Mg-ennched brines of
the Dead Sea.
Active tectonic processes that control all aspects of the Dead Sea have created
an environment that has mfluenced the course of human history as the critical land
bridge between the continents ofAfrica, Europe and Asia. The shores of the Dead
Sea are part of the Fertile Crescent and the region has played an important role in
Near Eastern prehistory and archeology. The historical and archaeological associa-
tions of this area are extensive. To name but few, it is in this region that Jericho, the
oldest city in the world is located, the Dead Sea scrolls were found and Sodom and
Gomorrah once existed. Many historians and archaeologists believe that the region
has much to yield in regard to biblical understandmg.