Nicolas Waldmann

Northward intrusions of low- and mid-latitude storms across the Saharo-Arabian belt during past interglacials

The rain regime of the Levant during the late Quaternary was controlled primarily by Mediterranean cyclonic systems associated with North Atlantic climate shifts. Lake levels in the Dead Sea basin have been robust recorders of the regional hydrology and generally indicate highstand (wet) conditions throughout glacial intervals and lowstands (dry) during interglacials. However, sporadic deposition of travertines and speleothems occurred in the Negev Desert and Arava Valley during past interglacials, suggesting intrusions of humidity from southern sources probably in association with enhanced activity of mid-latitude Red Sea synoptic troughs and/or low-latitude tropical plumes. The southerly incursions of wetness were superimposed on the long-term interglacial Levantine arid conditions, as refl ected by the current prevailing hyperaridity, and could have had an important impact on human migration through the Red Sea‐Dead Sea corridor.

A Holocene record of snow-avalanche and flood activity reconstructed from a lacustrine sedimentary sequence in Oldevatnet, western Norway

Two lacustrine sediment cores from Oldevatnet in western Norway have been studied in order to produce a record of floods, mass-wasting events and glacier fluctuations during the last 7300 years. River floods, density currents and snow-avalanches have deposited distinct ‘event layers’ at the lake floor throughout this time interval. In this study, a novel approach has been applied to distinguish event layers from the continuous background sedimentation, using Rb/Sr-ratios from X-Ray Fluorescence data. Grain-size distribution and the sedimentological parameters ‘mean’ and ‘sorting’ were used to further infer the depositional processes behind each layer. Our data suggest a record dominated by snow-avalanches, with the largest activity occurring during the ‘Little Ice Age’ (LIA). This increase in snow-avalanche activity observed during the LIA was probably caused by a combination of generally increasing winter precipitation and the advance of local glaciers towards the steep valley sides. Several fluctuations in snow-avalanche activity are also recognized prior to the LIA. Proxies of glacial activity from the background sediments indicate a similar development as earlier palaeoclimatic reconstructions from the area. It differs from previous reconstructions, however, by suggesting a lower glacial activity in the period from 2200 to 1000 cal. yr BP.

Late Pleistocene Environmental Change in Eastern Patagonia and Tierra del Fuego – A Limnogeological Approach

Publisher Summary This chapter focuses on geophysical, sedimentological, and geochemical results from several lacustrine basins in eastern Patagonia and Tierra del Fuego. The chapter reviews a series of case studies that combine seismic stratigraphy and multiproxy results of seismically targeted sediment cores. The combination of these results provides information essential to the interpretation of the paleoclimate evolution of southernmost eastern Patagonia for the Late Quaternary. The examples selected to illustrate a range of environments include (1) Northernmost Patagonia, (2) Central Patagonia, and (3) Southernmost Patagonia. The main goals pursued with these case studies are (1) to check on the timing and magnitude of the observed stepwise climatic evolution of the Lateglacial–Holocene transition; (2) to identify latitudinal variations during the Early Holocene; (3) to spot changes in El Nino Southern Oscillation (ENSO) activity during the second part of the Holocene; and (4) to highlight new evidence for the Little Ice Age (LIA) at different latitudes.

Evidences for centennial dry periods at ~3300 and ~2800 cal. yr BP from micro-facies analyses of the Dead Sea sediments

Laminated lake sediments from the Dead Sea basin provide high-resolution records of climatic variability in the eastern Mediterranean region, which is especially sensitive to changing climatic conditions. In this study, we aim on detailed reconstruction of climatic fluctuations and related changes in the frequency of flood and dust deposition events at ca. 3300 and especially at 2800 cal. yr BP from high-resolution sediment records of the Dead Sea basin. A ca. 4-m-thick, mostly varved sediment section from the western margin of the Dead Sea (DSEn – Ein Gedi profile) was analysed and correlated to the new International Continental Scientific Drilling Program (ICDP) Dead Sea Deep Drilling Project core 5017-1 from the deep basin. To detect even single event layers, we applied a multi-proxy approach of high-resolution microscopic thin section analyses, micro-X-ray fluorescence (µ-XRF) element scanning and magnetic susceptibility measurements, supported by grain size data and palynological analyses. Based on radiocarbon and varve dating, two pronounced dry periods were detected at ~3500–3300 and ~3000–2400 cal. yr BP which are differently expressed in the sediment records. In the shallow-water core (DSEn), the older dry period is characterised by a thick sand deposit, whereas the sedimentological change at 2800 cal. yr BP is less pronounced and characterised mainly by an enhanced frequency of coarse detrital layers interpreted as erosion events. In the 5017-1 deep-basin core, both dry periods are depicted by halite deposits. The onset of the younger dry period coincides with the Homeric Grand Solar Minimum at ca. 2800 cal. yr BP. Our results suggest that during this period, the Dead Sea region experienced an overall dry climate, superimposed by an increased occurrence of flash floods caused by a change in synoptic weather patterns.

Claim of largest flood on record proves false

A study of paleofloods in the Gardon River in southern France reveals the occurrence of past extreme floods that were larger than any observed historically. From 8 to 9 September 2002, during the course of the study by a complete coincidence, an extreme flood claimed the lives of 21 people and caused millions of dollars worth of damage to the towns and villages along the river. This flood was larger in magnitude than any flood on record, according to gaged data since 1890. An autumn storm, which is typical of this region, struck with immense force. The rain cell migrated from the lower reaches of the basin on the evening of 8 September to the upper parts of the basin, producing 680 mm of rain in 20 hours.The floods peak discharge is preliminary estimated at 6000 m3 s−1. This flood is now considered by the media and professionals to be “The largest flood on record.” However, our research proves otherwise.

Seismic Geomorphology of the Israel Slump Complex in the Levant Basin (SE Mediterranean)

Mass transport complexes (MTCs) are significant constituents of the post-evaporitic overburden in the Levant Basin, offshore Israel. Analysis of a new 3D seismic dataset offshore central Israel reveals that the Israel Slump Complex (ISC) consists of three stacked mass transport deposits (MTDs). The MTDs vary in lateral extent from between ~351 and 752 km2 with thicknesses between ~190 and 325 m, accounting for a remobilised sediment volume of ~35–94 km3. Interestingly, each MTD is unique, exhibiting different geometries, internal architectures, and halokinetic-related imprints. We document a novel palm-like erosional morphology, blocky facies, arcuate facies, mounded structure, syn-depositional thrust systems, and a channelised geometry. These configurations indicate different transport distance, mechanics, and kinematic history for each MTD within the complex, and may suggest different trigger events. The results of this study shed light on the interplay of multiple MTDs within a greater MTC. It also provides new insights into the nature and formation of the ISC in the offshore area of central Israel, which arose from at least three short-timed mass wasting events during the Late Pliocene. Likewise it may serve as an analogue to understand the configurations of MTDs in basins with well-developed evaporite layers.