The Dead Sea, located in the Dead Sea Basin (DSB) at the lowest continental elevation on Earth (~425 m below sea level), has alternately expanded during ice ages and contracted during warmer periods. At its maximum level during the last ice age as glacial Lake Lisan (~165 mbsl), it filled the DSB from its present location northward to include the Sea of Galilee. Its changing size and composition through time reflect the climatic-hydrologic history and the tectonic architecture of its location, in the mid-latitudes, on the continent, and on the boundary between the Saharan desert and Mediterranean climate zones. These changes are recorded and preserved in the lake sediments, giving them unique potential for investigating the expansion and contraction of these climatic zones, as well as the linkages between high latitude and tropical climate. Moreover, because the DSB formed by the Dead Sea Transform Fault, it is in an active tectonic region and sediments preserve the earthquake history. The DSB is also the locus of humankind?s migration out of Africa, and the home of peoples from Paleolithic to modern times. Studies of the sedimentary sections exposed on the Dead Sea margins have been applied to issues with global and regional implications associated with paleoclimate, tectonics, paleoseismology, paleomagnetism, and human history.
The International Continental Scientific Drilling Program (ICDP) agreed in October 2009 to fund the Dead Sea Deep Drilling Project, which is expected to recover the longest, most continuous, and best-preserved paleo-environmental and paleo-seismic archive in the Middle East, with >500 m of core and covering the last ~800-1000 ka. The ICDP proposal included PIs from Israel, Germany, Japan, Switzerland, and the USA. The ICDP is providing $800,000, ~40% of the budget of $2.1M, and has requested that the PIs seek matching funds from their respective countries.
Broader impacts: The DSDDP is now a collaboration of six countries (Israel, Germany, Japan, Norway, Switzerland, USA). The Dead Sea Basin is a key region for human development as the route that humans took out of Africa, and previous work has demonstrated the value of sediments from older lakes (e.g. Lake Lisan) for paleo-environmental, paleo-tectonic, and archeological studies. The results will thus be of great interest to scientists in a variety of disciplines, and the public. These cores will be used for numerous graduate and undergraduate thesis projects. The PIs have a long track record in mentoring postdocs, graduate students, and undergraduates. Moreover, the project needs staffing and there will be direct participation by US-based undergraduate and graduate students. The region is water-starved, with virtually all of the available fresh water in the region used by the surrounding countries, which adds severe additional stresses to already poor international relations. The observation from the early drilling phase, that the Dead Sea dries up periodically, shows that fresh water resources have diminished in the past, and climate models indicate that this will happen in the future with increased aridity. Thus learning about the history of aridity in the past is important to be able to plan for future water scarcity. The Dead Sea has a special place in the public imagination because of the associations with the stories of the Bible, and the drilling program will generate much media coverage due to its location and engender increased public interest in the geosciences. The Israeli team is making major attempts to include scientists from the Jordan and Palestine, and if this results in any additional communication and cooperation it will be a major broader impact.
This grant provided NSF support for an international effort, partly funded by the International Continental Scientific Drilling Program, to obtain deep drill cores from the Dead Sea, on the border of Israel, Jordan, and Palestine. The primary purpose was to recover a continuous record of the climate history and the earthquake history of the Middle East, going back through multiple ice ages and warm ages. The Dead Sea and its surrounding region are of special interest for many reasons. Its surface is the lowest elevation on the continents (~1400 feet below sea level) and it is the saltiest water body on the Earth (~10 times seawater). The Dead Sea Valley has been the primary pathway of humankind’s migration out of Africa, and the home of peoples since the Stone Age. There has been a lot of interest from the news media because of the region’s association with the birth of three major religions. The Dead Sea Valley itself formed through the movement of a "transform fault" (like the San Andreas Fault in California), and Dead Sea sediments preserve the history of earthquake activity. Moreover, it is located at the boundary between the Arabian-Sahara deserts and the Mediterranean climate zones, and sensitive to the starkly contrasting (arid versus temperate) climate and hydrological conditions of these zones. The climate changes through time have likely played important roles in the development of ancient civilizations. The Dead Sea was drilled at two sites: one is near the deepest part (the lake floor is ~980 feet below the water surface), the second is near the shore (Figure 1). The layering of the sediments (Figures 2,3) record summer and winter seasonal conditions though time. During ice ages, lake evaporation during dry summers caused and precipitation of calcium carbonate (aragonite), and stormy winters brought in mud and dust from outside the valley, together resulting in the white and dark layering (Figure 2). During periods of sustained aridity, calcium sulfate (gypsum) layers were deposited. During the arid periods of warm (interglacial) ages, salt (halite) is deposited. The drilling was a huge success. Coring reached a depth of ~1500 feet below the lake bottom at the deep site and ~1150 feet at the shallow site. The seasonal record goes back ~200,000 years, through the last two warm (interglacial) periods, two full ice ages, and part of a third one. An important discovery is layer of rounded pebbles (Figure 4) at the deep site that appear to be a beach deposit during the last interglacial (prior to the last ice age), which overlies ~150 feet of mainly salt, thus documenting a major drydown of the lake during that time. This discovery has important implications for the present day. Fresh water is a precious resource in this region, and has been a source of regional conflict. All of the countries in the drainage basin (Israel, Palestine, Jordan, Syria, and Lebanon) use all of the available fresh water. This discovery shows that with absolutely no interference by humans, the fresh water availability declined to the point that a major drydown of the lake occurred. It emphasizes the sensitivity of the regional fresh water resources to climate changes, and the need to prepare for the consequences in a warming world. The project provided opportunities for three undergraduate students, a Ph.D. student, and a postdoctoral scientist to participate in the drilling campaign, and to participate in the core opening campaign and the first sampling campaign.
