<Tr> <Td_colspan="14"> Source: Israel Meteorological Service </Td> </Tr> <P> With 34.2% salinity (in 2011), it is one of the world's saltiest bodies of water, though Lake Vanda in Antarctica (35%), Lake Assal in Djibouti (34.8%), Lagoon Garabogazköl in the Caspian Sea (up to 35%) and some hypersaline ponds and lakes of the McMurdo Dry Valleys in Antarctica (such as Don Juan Pond (44%)) have reported higher salinities . </P> <P> Until the winter of 1978--79, when a major mixing event took place, the Dead Sea was composed of two stratified layers of water that differed in temperature, density, age, and salinity . The topmost 35 meters (115 ft) or so of the Dead Sea had an average salinity of 342 parts per thousand (in 2002), and a temperature that swung between 19 ° C (66 ° F) and 37 ° C (99 ° F). Underneath a zone of transition, the lowest level of the Dead Sea had waters of a consistent 22 ° C (72 ° F) temperature and complete saturation of sodium chloride (NaCl). Since the water near the bottom is saturated, the salt precipitates out of solution onto the sea floor . </P> <P> Beginning in the 1960s, water inflow to the Dead Sea from the Jordan River was reduced as a result of large - scale irrigation and generally low rainfall . By 1975, the upper water layer was saltier than the lower layer . Nevertheless, the upper layer remained suspended above the lower layer because its waters were warmer and thus less dense . When the upper layer cooled so its density was greater than the lower layer, the waters mixed (1978--79). For the first time in centuries, the lake was a homogeneous body of water . Since then, stratification has begun to redevelop . </P>

Whats at the bottom of the dead sea