A wetland oasis at Wadi Gharandal spanning 125-70 ka on the human migration trail in southern Jordan

Former lakes and wetlands can provide valuable insights to the late Pleistocene environments encountered by the first humans to enter the Levant from Africa. Fluvial incision along Wadi Gharandal in hyperarid southern Jordan has exposed remnants of a small riverine wetland that accumulated as a sedimentary sequence up to similar to 20 m thick. We conducted a chronometric and sedimentological study of this wetland, including 10 optically stimulated luminescence dates. The wetland sequence accumulated during the period similar to 125 to 70 ka in response to a positive water balance coupled with a (possibly coseismic) landslide that dammed the outlet. The valley fill was dissected when the dam was incised shortly after similar to 36 +/- 3 ka. Comparison of our ages with regional palaeoclimate indicates that the Gharandal oasis developed during the relatively humid Marine Isotope Stage 5. A minimum age of 74 +/- 7 ka for two Levallois flakes collected from stratified sediments suggests that the oasis was visited by humans during the critical 130-90 ka time window of human migration out of Africa. Gharandal joins a growing network of freshwater sites that enabled humans to cross areas of the Levant and Arabia along corridors of human dispersal.

Automated summary

The study of sediment sequences in ancient wetlands can provide insights into the environmental changes when humans first entered the Levant from Africa. Analysis of ages from stratified sediments suggests that the Gharandal oasis formed during a relatively humid period and was visited by humans during the critical time window of human migration out of Africa, playing a role in dispersal.