The present study documents coastal processes of movement and subsidence that affect the clayey sediments of the exposed mudflats ('mudflat sediments') on the receding western shore of the Deep Dead Sea ('western Dead Sea shore') and the formation of subsidence features: subsidence strips and clustered sinkholes. The properties of the clayey sediments that promote movement and subsidence and the development of the subsidence features in the exposed mudflats are the unconsolidated fine-particle texture composed of clay and carbonate minerals, their being dry near the surface and wet at the subsurface, their soaking with saline water and brine and the abundance of smectitic clays saturated with sodium and magnesium. Field observations indicate that narrow subsidence strips with/without clustered sinkholes were developed by movement and subsidence in mudflat sediments via lateral spreading. Wide subsidence strips with clustered sinkholes were developed via increased subsidence in mudflat sediments due to the progress of dissolution within a subsurface rock-salt unit. The emergence of sinkholes occurs via subsidence of mudflat sediments into subsurface cavities resulting from dissolution within a subsidence rock-salt unit. The coastal processes on the receding Dead Sea shore and the formation of the subsidence features are part of the adjustment of the Dead Sea periphery to the lowering of the base level. A contribution of slow mass movement seaward to the coastal processes on the receding Dead Sea shore is indicated.

Alluvial fans are important paleoclimatic archives, thatmay record high-frequency climatic oscillations. However, climate signals may be overprinted or even be destroyed by autogenic processes caused by channel avulsion and lobe switching. Here we present new data from two different Late Pleistocene (MIS 3-2) alluvial fan systems in northern Germany and compare these systems to experimental alluvial fans and other field examples. The selected fan systems formed under similar climatic and tectonic conditions, but differ in size, type, and drainage area allowing to estimate the role of climate and autogenic controls on flow processes, facies architecture, and fan-stacking patterns. Luminescence dating is used to determine the timing of fan onset and aggradation. Fan onset occurred in response to climate change at the end of MIS 3 when temperatures decreased and periglacial climate conditions were established in northern central Europe. A related increase in sediment supply and strongly variable precipitation patterns probably promoted fan formation. The major period of fan aggradationwas approximately between 33 and 18 ka, followed by fan inactivity, abandonment, and incision during the Lateglacial. The highest aggradation rates occurred during the early stage of fan building, when up to 35 m thick sediment accumulated within a few thousand years. Sand-rich, sheetflood-dominated fans are related to larger, low-gradient fan catchments. Steep depositional fan slopes (5 degrees 17 degrees) and short-lived high-energy floods promoted supercritical flowconditions. Well sorted, sediment-laden, rapidly waning flows favored the deposition and preservation of supercritical bedforms and allowed for the aggradation of stable antidunes. Steep, dip-slope catchments enhanced stream gradients and promoted the transport of coarser sediments. These fans have lower gradient slopes (2-6 degrees) and are dominated by channelized flows, alternating with periods of unconfined sheetfloods. Meter-scale coarsening upward successions, characterized by sandy sheetflood deposits at the base, overlain by multilateral or smaller single-story gravelly channel fills may be related to highfrequency climatic fluctuations or seasonal fluctuations in water and sediment supply. These coarsening-upward successions are commonly bounded by a paleo-active layer, from which ice-wedge casts penetrate downwards. The comparison to experimental fans and other field examples implies that the recurrent pattern ofmultistory, multilateral and single-story channel bodieswith a lateral offset to vertical stacking patternmost probablywas controlled by autogenic switch in an avulsion-dominated system. The change in deposition from alluvial-dominated processes to aeolian sedimentation with minor alluvial influences during the Lateglacial records alternation of dry and ephemeral wetter phases that are related to rapid climatic variations. The main phase of aeolian sand-sheet deposition probably correlates with Heinrich event H1 between approximately 18-16 ka and reflects sedimentation in response to aridification and highmeanwind speeds.

Fan-shaped landforms occur in all climatic regions on Earth. They have been extensively studied in many of these regions, but there are few studies on fans in periglacial, Arctic and Antarctic regions. Fans in such regions are exposed to many site-specific environmental conditions in addition to their geological and topographic setting: there can be continuous to discontinuous permafrost and snow avalanches and freeze-thaw cycles can be frequent. We study fans in the high-Arctic environment of Svalbard to (1) increase our fundamental knowledge on the morphology and morphometry of fans in periglacial environments, and (2) to identify the specific influence of periglacial conditions on fans in these environments. Snow avalanches have a large geomorphic effect on fans on Svalbard: the morphology of colluvial fans is mainly determined by frequent snow avalanches (e.g., flattened cross-profiles, exposed fine-grained talus on the proximal fan domain, debris horns and tails). As a result, there are only few fans with a rockfall-dominated morphology, in contrast to most other regions on Earth. Slush avalanches contribute significant amounts of sediment to the studied alluvial fans. The inactive surfaces of many alluvial fans are rapidly beveled and leveled by snow avalanches, solifluction and frost weathering. Additionally, periglacial reworking of the fan surface often modifies the original morphology of inactive fan surfaces, for example by the formation of ice-wedge polygons and hummocks. Permafrost lowers the precipitation threshold for debris-flow initiation, but limits debris-flow volumes. Global warming-induced permafrost degradation will likely increase debris-flow activity and -magnitude on fans in perigladal environments. Geomorphic activity on snow avalanche-dominated colluvial fans will probably increase due to future increases in precipitation, but depends locally on climate-induced changes in dominant wind direction. (c) 2015 Elsevier BM. All rights reserved.

Alluvial fans in southern Monglia occur along a group of narrow discontinuous mountain ranges which formed as transpressional uplifts along a series of strike-slip faults. They provide information on the nature of neotectonic activity in the eastern Gobi Altai range acid on palaeoclimate change. Alluvial fan formation was dominated by various geomorphological processes largely controlled by climatic changes related to an increase in aridity throughout late Quaternary times. Their sedimentology shows that initially they experienced humid conditions, when the sedimentary environments were dominated by perennial streams, followed by a period of increasing aridity, during which coarse fanglomerates were deposited in alluvial fans by ephemerial streams and active-layer structures were produced by permafrost within the alluvial fan sediments. With climatic amelioration during early Holocene times, the permafrost degraded and fan incision and entrenchment dominated. Sedimentation was then confined to the upper reaches of the fans, adjacent to steep mountain slopes, and within the entrenched channels. The alluvial fans have been neotectonically deformed, faulted and their surface warped by small thrust faults that propagate from the mountain fronts into their forelands. Localised uplift rates are in the order of 0.1 to 1 m Ka(-1). (C) 1997 John Wiley & Sons, Ltd.