New York: Scientists have discovered the oldest geological evidence of man-made impact on the environment from 11,500 years ago in the Dead Sea in Israel.
The discovery took place as part of the Dead Sea Deep Drilling project which harnessed a 1,500-foot-deep drill core to delve into the Dead Sea basin.
The core sample, which provided the researchers with a sediment record of the last 220,000 years, showed basin-wide erosion rates dramatically opposite to the known tectonic and climatic regimes of the period.
Lead author Shmuel Marco, Professor at the Tel Aviv University in Israel said,"We noted a sharp threefold increase in the fine sand that was carried into the Dead Sea by seasonal floods. This intensified erosion is incompatible with tectonic and climatic regimes during the Holocene, the geological epoch that began after the Pleistocene some 11,700 years ago."
The study showed that the erosion occurred during the Neolithic Revolution, the wide-scale transition of human cultures from hunting and gathering to agriculture and settlement. The shift resulted in an exponentially larger human population on the planet.
Marco said,"Natural vegetation was replaced by crops, animals were domesticated, grazing reduced the natural plant cover, and deforestation provided more area for grazing."
He added,"All these resulted in the intensified erosion of the surface and increased sedimentation, which we discovered in the Dead Sea core sample."
The researchers are currently in the process of recovering the record of earthquakes from the same drill core.
Marco said,"We have identified disturbances in the sediment layers that were triggered by the shaking of the lake bottom. It will provide us with a 220,000-year record -- the most extensive earthquake record in the world."
The study was published in the journal Global and Planetary Change.
(With IANS inputs)