Geologists are used to studying rock layers in the depths of the earth, but in a recent study conducted in the Eilat Bay region, Israeli researchers uncovered findings that shed new light on humanity's development. According to these new findings, more than 100,000 years ago there were fresh water sources in the Eilat Bay region, which apparently helped modern man (Homo sapiens ) to migrate across this arid region in the direction of Asia and Europe.

Prof. Boaz Lazar of the Earth Sciences Institute at the Hebrew University of Jerusalem and Dr. Moti Stein of the Israel Geological Survey carried out a study in the area south of the Jordanian city of Aqaba. There they examined the changes that took place in a coral reef that was lifted above sea level and transformed into a fossil reef. They recently published their findings in the journal "Geology."

According to Stein, one of the important aspects of researching fossil reefs is that it is possible to extract from the corals information about their age, and also to obtain information about changes that occurred at sea level during various periods. There are reefs in the Eilat Bay area that are above sea level today. The reefs were left stranded by a series of earthquakes that hit the region thousands of years ago and created the Dead Sea Transform.

Corals, which are marine animals, use various substances to build the skeleton on which a reef is constructed. The corals in a briny marine environment are generally composed of the mineral aragonite. However, earlier studies revealed that when the coral reef comes into contact with fresh water, aragonite undergoes a process of re-crystallization into the mineral calcite.

"Over the years we noticed that many of the corals in the Eilat Bay area are made of calcite," Stein says. "This indicates that at some stage they came into contact with fresh water, and that of course is unusual in a region that is considered one of the most arid in the world. But until recently we didn't know how to date the period of the contact with fresh water."

Lazar and Stein estimate that the corals came into contact with fresh water some 140,000 years ago, in what is termed an interglacial period. The period in question corresponds, according to anthropological and archaeological studies, to the period when Homo sapiens began migrating from Africa to other continents, thereby creating the basis for the spread of human settlement.

"We know that during this period there were large amounts of rain in the region, and surmise that reservoirs formed of groundwater that flowed toward the sea, came into contact with the corals, and brought about the changes that took place in them," Stein says. "This leads us to posit that these waters also served human beings who reached the area, and thereby enabled them to subsist in this environment."