The evolution of the terrestrial-terminating Irish Sea glacier during the last glaciation     

Richard Christopher Chiverrell  Geoff Stephen Powell Thomas  Matthew Burke  Alicia Medialdea  Rachel Smedley  Mark Bateman  Chris Clark  Geoffrey A. T. Duller  Derek Fabel  Geraint Jenkins  Xianjiao Ou  Helen Marie Roberts  James Scourse 《第四纪科学杂志》2021,36(5):752-779

Here we reconstruct the last advance to maximum limits and retreat of the Irish Sea Glacier (ISG), the only land-terminating ice lobe of the western British Irish Ice Sheet. A series of reverse bedrock slopes rendered proglacial lakes endemic, forming time-transgressive moraine- and bedrock-dammed basins that evolved with ice marginal retreat. Combining, for the first time on glacial sediments, optically stimulated luminescence (OSL) bleaching profiles for cobbles with single grain and small aliquot OSL measurements on sands, has produced a coherent chronology from these heterogeneously bleached samples. This chronology constrains what is globally an early build-up of ice during late Marine Isotope Stage 3 and Greenland Stadial (GS) 5, with ice margins reaching south Lancashire by 30 ± 1.2 ka, followed by a 120-km advance at 28.3 ± 1.4 ka reaching its 26.5 ± 1.1 ka maximum extent during GS-3. Early retreat during GS-3 reflects piracy of ice sources shared with the Irish-Sea Ice Stream (ISIS), starving the ISG. With ISG retreat, an opportunistic readvance of Welsh ice during GS-2 rode over the ISG moraines occupying the space vacated, with ice margins oscillating within a substantial glacial over-deepening. Our geomorphological chronosequence shows a glacial system forced by climate but mediated by piracy of ice sources shared with the ISIS, changing flow regimes and fronting environments.  相似文献   

Late Pleistocene and Holocene Afromontane vegetation and headwater wetland dynamics within the Eastern Mau Forest,Kenya     

Esther N. Githumbi  Colin J. Courtney Mustaphi  Rob Marchant 《第四纪科学杂志》2021,36(2):239-254

The Mau Forest Complex is Kenya's largest fragment of Afromontane forest, providing critical ecosystem services, and has been subject to intense land use changes since colonial times. It forms the upper catchment of rivers that drain into major drainage networks, thus supporting the livelihoods of millions of Kenyans and providing important wildlife areas. We present the results of a sedimentological and palynological analysis of a Late Pleistocene–Holocene sediment record of Afromontane forest change from Nyabuiyabui wetland in the Eastern Mau Forest, a highland region that has received limited geological characterization and palaeoecological study. Sedimentology, pollen, charcoal, X-ray fluorescence and radiocarbon data record environmental and ecosystem change over the last ~16 000 cal a bp. The pollen record suggests Afromontane forests characterized the end of the Late Pleistocene to the Holocene with dominant taxa changing from Apodytes, Celtis, Dracaena, Hagenia and Podocarpus to Cordia, Croton, Ficus, Juniperus and Olea. The Late Holocene is characterized by a more open Afromontane forest with increased grass and herbaceous cover. Continuous Poaceae, Cyperaceae and Juncaceae vegetation currently cover the wetland and the water level has been decreasing over the recent past. Intensive agroforestry since the 1920s has reduced Afromontane forest cover as introduced taxa have increased (Pinus, Cupressus and Eucalyptus).  相似文献   

Geoarchaeological evidence on a Late Bronze Age earthquake,Ohrid Basin (North Macedonia)     

J. Hošek  M. Verčík  P. Pokorný  J. Beneš  V. Komárková  T. Radoměřský  N. Atanasoska  V. Todoroska  P. Ardjanliev 《第四纪科学杂志》2021,36(6):1003-1012

Geoarchaeological investigations on the northeastern shore of Lake Ohrid revealed 3.5 m thick deepwater lacustrine sediments overlying terrestrial vegetation macrofossils, worked wood and abundant potsherds dated to the Late Bronze Age (LBA). Distinct contact of deepwater sediment with the sub-aerial weathered limestone bedrock point to a sudden increase in lake level. According to radiocarbon data, catastrophic flooding occurred shortly after 1214 yr bc. Because the area is located in a highly active seismic zone, we propose that this event was caused by tectonically induced, metre-scale coseismic subsidence related to faults bordering the Ohrid alluvial plain. Moreover, this event coincides well with a dramatic switch in the habitation and settlement strategy in the region. More important, however, is the finding that the age of the proposed massive tectonic event and change in habitation lies within the interval of the proposed ‘earthquake storm’ in the eastern Mediterranean dated to 1225–1175 bc. As the Ohrid-Korça zone belongs to the same tectonic province, a relationship between the abovementioned earthquakes and the proposed event can be expected. This research therefore might provide the first direct evidence of a large-scale earthquake event linkable to the LBA collapse of Europe's first urban civilisation in the Aegean.  相似文献   

The past in dust: current trends and future directions in Pleistocene geoarcheology of European loess     

Wei Chu  Janina J. Nett 《第四纪科学杂志》2021,36(8):1279-1292

Loess is a main archive of Pleistocene landscapes and environments and therefore has an important connection to the preservation and interpretation of Paleolithic sites. In Europe, anthropogenic sites have been found in loess because of past local occupation. At one extreme, sites are well preserved with minimal disturbance often accompanied by embedded proxies to estimate ecological parameters. On the other hand, loess deposits have undergone post-depositional alterations such as weathering, pedogenesis or bioturbation due to changing environmental conditions or other disturbances that obscure anthropogenic sites. We outline the current state of research and connections between Paleolithic archeology and loess research while introducing a series of subsequent regional case studies as part of a special issue. We also make recommendations for future work to incorporate a wider variety of methods to create more robust inferences on hominin and environmental evolution and their connections.  相似文献   

Long- and short-term volcanic hazard assessment of El Chichón Volcano (Mexico) through Bayesian inference     

Alatorre-Ibargüengoitia  Miguel A.  Hernández-Urbina  Karina  Ramos-Hernández  Silvia G. 《Natural Hazards》2021,106(1):1011-1035

Natural Hazards - The 1982 eruption of El Chichón volcano constitutes the worst volcanic disaster in Mexico producing more than 2000 fatalities, thousands of displaced people and severe...  相似文献   

Methodological challenges to confirmatory latent variable models of social vulnerability     

Goodman  Zachary T.  Stamatis  Caitlin A.  Stoler  Justin  Emrich  Christopher T.  Llabre  Maria M. 《Natural Hazards》2021,106(3):2731-2749

Natural Hazards - Socially vulnerable communities experience disproportionately negative outcomes following natural disasters and underscoring a need for well-validated measures to identify those...  相似文献   

Hydrological basis of the Devils Lake,North Dakota (USA), terminal lake flood disaster     

Todhunter  P. E. 《Natural Hazards》2021,106(3):2797-2824

Devils Lake, a terminal lake in northeast North Dakota (USA), has experienced catastrophic flooding since 1993. From January 31, 1993, to December 31, 2014, lake level rose from 433.62 to 442.44 m, lake area expanded from 179.9 to 653.5 km², and lake volume increased from 0.70 to 3.80 km³. More than $1 billion ($USD) has been spent in government payments to mitigate direct, primary, tangible flood damages. This paper provides a case study of the hydrological basis of the Devils Lake flood disaster. The unique geomorphic setting, paleoclimatic record, and hydroclimatic conditions of the region are summarized, and a wide range of hydroclimatic data is examined to provide a broad understanding of the physical basis of the flood disaster. The primary cause of the disaster was a transition to a sustained wetter climate that resulted in a dramatic response in basin hydrological variables in 1993. The transition from a long-term dry period to a long-term wet period caused the lake water budget to begin to change from an atmosphere-controlled water budget dominated by precipitation input to an amplifier lake water budget dominated by surface runoff input to the lake. Other important hydrological factors include a nonlinear precipitation–runoff relationship following the long-term drought, fill-spill and fill-merge hydrological behavior that is characteristic of wetland complexes, an increase in the lake area-to-basin area ratio, and the critical role of frozen soils in controlling infiltration and runoff production of spring snowmelt. Engineering works to manage lake volume through two outlets have reduced, but not entirely eliminated, future flood risk.

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Gender-based differences in flood vulnerability among men and women in the char farming households of Bangladesh     

Naz  Farha  Saqib  Shahab E. 《Natural Hazards》2021,106(1):655-677

Natural Hazards - Gender and vulnerability are important issues to examine in the context of flooding caused by climate change. Men and women around the world adapt differently to climate change...  相似文献   

On the use of synthetic tropical cyclones and hypothetical events for storm surge assessment under climate change     

Ruiz-Salcines  Pablo  Appendini  Christian M.  Salles  Paulo  Rey  Wilmer  Vigh  Jonathan L. 《Natural Hazards》2021,105(1):431-459

Natural Hazards - This study presents a new approach to assess storm surge risk from tropical cyclones under climate change by direct calculation of the local flood levels using a limited number of...  相似文献   

Avalanche hazard mitigation in east Karakoram mountains     

Singh  Amreek  Juyal  Vikas  Kumar  Bhupinder  Gusain  H. S.  Shekhar  M. S.  Singh  Paramvir  Kumar  Sanjeev  Negi  H. S. 《Natural Hazards》2021,105(1):643-665

Natural Hazards - Karakoram mountains range in north-western part of Himalayas is about 500 km in length and hosts some of the world’s highest peaks and longest glaciers. It is...  相似文献