Quaternary palaeogeomorphologic evolution of the Wadi Faynan area, Southern Jordan

The Faynan area comprises a complex assemblage of deposits and landforms of varying nature, age and position in the landscape. The dominant facies are fluvial, slope and aeolian. At least eight palaeochannels are present at different heights within the Wadis Dana and Ghuwayr. Fewer terraces are preserved in the Wadi Faynan. Planated surfaces leaving lowgradient straths, rock-cut channels and fluvial deposits are all evident. The continuing drop in regional base level as a result of subsidence of the Dead Sea trough has driven incision and aided in the retention of many of the terrace deposits as they have been abandoned as the wadi systems have eroded downwards. Calcretisation has enhanced the preservation potential of many of the fluvial deposits. A large proportion of these deposits are comparable to those found in the modern wadi systems, and it is thought that they formed under arid conditions similar to those that exist today. Two of the terrace deposits appear to reflect slightly wetter conditions as they consist of finer grained, better sorted materials and display evidence of biological activity. There are at least four distinct alluvial fan and slope deposits that have formed at the edge of various mountain fronts. The fans have been entrenched to varying degrees and are likely to have formed at different times in the Quaternary, possibly when conditions were more humid or during periods of increased tectonic activity. Aeolian deposits indicate a marginally drier phase in the Late Glacial maximum and similar sediments of mid-Holocene age could either reflect increasing aridity at this time as has been suggested by Frumkin et al. (1991) and/or be a result of the increasing impact of humans on the landscape. Many of the deposits are beyond the age range of optically stimulated luminescence (OSL) and radiocarbon dating techniques, but a proposed stratigraphy is supported by some numerical dates on the younger deposits and associated archaeological artefacts.