Late Quaternary rapid talus dissection and debris flow deposition on an alluvial fan in Syria

Landform development in an arid alluvial fan/source basin system in northwest Syria was reconstructed based on field surveys and correlated with dated stratigraphy in the nearby Dederiyeh Cave. During the Last Glacial Maximum, talus deposits were stored in the V-shaped valley of the source area and associated fan gravels became firmly cemented by carbonate, reflecting a slow deposition rate. In the Late Glacial, the lower parts of talus slopes were quickly dissected due to increased storm activity, and boulder debris flows were deposited on the fan surface. Subsequently, water flow removed the sandy matrix of the debris flow deposits on the northern half of the fan surface and that of talus deposits along the trunk stream of the upstream area. This was followed by a period of stability without significant geomorphic change during the Holocene. The inferred rapid geomorphic response to climatic change in the form of talus dissection, debris flows, and fan deposition contrasts with the notion that geomorphic systems in arid regions respond slowly to change in external variables.