New York, June 8 (IANS): Scientists have discovered wide rates of erosion dating back to 11,500 years ago from the Dead Sea in Israel -- touted as the oldest geological evidence of man-made impact on the environment.
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.
"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," said lead author Shmuel Marco, Professor at the Tel Aviv University in Israel.
The study, published in the journal Global and Planetary Change, 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. "Natural vegetation was replaced by crops, animals were domesticated, grazing reduced the natural plant cover, and deforestation provided more area for grazing," Marco said.
"All these resulted in the intensified erosion of the surface and increased sedimentation, which we discovered in the Dead Sea core sample," he added. The researchers are currently in the process of recovering the record of earthquakes from the same drill core.
"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," Marco said.
