LATE QUATERNARY WETLAND DEPOSITS IN WADI HASA, JORDAN, AND THEIR IMPLICATIONS FOR PALEOENVIRONMENTAL RECONSTRUCTION

Wadi Hasa, located in central Jordan, flows west from the Jordan plateau into the Jordan Valley and Dead Sea. At the location where Wadi Hasa exits the plateau, it becomes deeply incised and switches from an intermittent dry stream to a perennial stream that supports in-stream wetlands. Late Quaternary wetland/lake deposits outcrop intermittently throughout Wadi Hasa and its tributaries beginning at the narrows where Wadi Hasa exits the plateau and continuing until ~8km downstream from this location.

Four time-stratigraphic units of wetland deposits have been identified within Wadi Hasa. Unit A deposits are mostly located at downstream locations and consist of very hard, consolidated, alluvial gravels cemented with secondary carbonate and gypsum with beds of wetland deposits. Unit A deposits are thought to be greater than 100 ka but as of yet have no age control. Unit B deposits are located in the downstream and central wadi area and consist of well-cemented wetland deposits that contain Middle Paleolithic archaeological materials that likely date between 100ka and 45 ka. Unit C deposits are located at the narrows and at several downstream locations. Radiocarbon dating of Upper Paleolithic archaeological material within the loosely cemented wetland deposits of Unit C gives an age range of 35 ka to 22 ka. Unit D deposits are likely Holocene in age and consist of uncemented alluvial gravels and wetland deposits that occur throughout the area.

Unit C deposits at the canyon narrows locality have been interpreted previously to be lake deposits that formed as a result of side-canyon damming by debris flow deposits. Unit C deposits, however, occur at the narrows locality and at several locations downstream from the supposed damming locality. Moreover, we did not identify any debris-flow deposits. We interpret Units B and C to be in-stream wetland deposits and that aggradation and incision of these deposits was controlled by the height of the local water table. Understanding the environment in which the Wadi Hasa deposits formed is integral in providing environmental context for the Middle to Upper Paleolithic archaeological material present throughout the area.