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Extreme floods are anticipated to become more frequent in a future warmer climate. However, the long-term alterations in flood patterns across different regions of Europe remain unclear. In this study, we present a 15,000-year record of extreme floods in the Duero River, located in the southwestern Atlantic region. We analysed slackwater flood sediments, quantified the discharge and timing of individual flood beds over millennial time scales, and identified their potential climate influences. The composite record includes at least 62 floods grouped into ten flood-rich periods (with an average duration of 230 years). A high-frequency phase of moderate-magnitude floods (>10 events) occurred at ∼11.6–11.5 ka, following a period of reduced flood activity during the Younger Dryas. Similar clusters of Early Holocene floods (10.8–10.3 ka, 9.5 ka) coincided with or preceded meltwater pulses from the North Atlantic. The absence of palaeoflood records with discharges exceeding 6100 m3/s during the Mid-Holocene suggests a decline in winter hydro-meteorological extremes. High flood magnitudes were recorded during transition periods toward cooler and wetter conditions at 4.4, 2.3, 0.5, and 0.11 ka with discharges ranging from 7600 to 10,000 m3/s. These periods were interpreted as indicative of a southward shift in cyclone tracks in Europe driven by negative phases of the North Atlantic Oscillation (NAO). Conversely, flood magnitudes decreased during past warmer climate conditions (1.7 ka, 0.9 ka, and the present), although flood frequency remained high. The current decline in flood frequency reflects an increase in flood regulation due to dams, but it is also consistent with the prevailing positive trend in the NAO observed over the last 40 years., Ministerio de Ciencia e Innovación (España), Dirección General del Agua, Fundación Biodiversidad, Union Europea, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

In the Huelva Coast of SW Spain erosion by recent marine storms revealed the presence of a paleosol where an extensive tracksite known as “Matalascañas Trampled Surface” (MTS) has been documented. The MTS includes tracks and trackways of large species of mammals, along with bird trace fossils, invertebrate burrows and root traces. Within this record, the presence of several hominin footprints and trackways stands out. Despite previous uncertainties about the producer of these footprints, new OSL age of 151 ± 11 ka secures their attribution to Neanderthals, the only hominins known to have been present in the Iberian Peninsula during the MIS6-5 transition. Moreover, typical Mousterian lithic industry with Levallois knapping was found associated with the ichnological record. This lithic industry is characterized by the selection of raw materials from outcrops in a short-distance range to the tracksite. The general characteristics of the lithics are derived both from the nature of the raw material and from the nature of the site itself, which cannot be seen as a settlement, but rather as a place of passage for fauna, including Neanderthals, where a few human individuals performed short-term activities, such as food procurement and/or meat processing.

Glacier outburstfloods are a major hazard in glacierized catchments. Global analyses have shownreduced frequency of glacierfloods over recent decades but there is limited longer-term data on eventmagnitude and frequency. Here, we present a Holocene palaeoflood record from the Río Baker (ChileanPatagonia), quantifying the discharge and timing of glacierfloods over millennial timescales. A cata-strophicflood of 110,000 m3/s (0.11 Sv) occurred at 9.6±0.8 ka, duringfinal stages of the Late GlacialInterglacial Transition, followed byfiveflood-phases coeval or post-dating Holocene neoglacials. Highestflood frequencies occurred at 4.3e4.4 ka, with 26floods of minimum discharges of 10,000e11,000 m3/s,and 0.6 ka with 10floods exceeding 4600e5700 m3/s. The largest modern outburstflood recordedsurpassed ~3810 m3/s. Thus glacierflood magnitude declines from the order of 0.1 to 0.01 Sv over theEarly to Mid Holocene, and to 0.001 Sv in the instrumental record.

In Alpine regions, speleothem development on karst systems largely occurs during warm interglacial or interstadial phases due to their limited growth during cold stages. Still, recent attention has been given to the role of clastic sediments in caves, less dependent on temperature conditions. Yet, only a small number of caves worldwide preserve both speleothems and detrital deposits. Here we present an outstanding record of fine-grain laminated sediments and carbonate speleothems from the Granito cave (South Central Pyrenees, Spain) associated with seasonal to annual hydroclimatic pulses through the Last Glacial Cycle (LGC). Analysis of cave clastic facies together with new absolute dates on glacial deposits along the valley has provided new insights into the karst-glacial interactions in relation with long-term landscape evolution, with support of geomorphological, sedimentological, mineralogical, palynological, geochemical and geochronological data (U/Th series, OSL and IRSL).The Granito cave was formed before 153.6±1.2 ky (Marine Isotopic Stage, MIS 6), as indicated by the oldest stalagmites dated in the cave, although speleothem formation occurred preferentially during MIS 5 and the Holocene interglacial stages. A 60 m thick clastic deposit was IRSL dated from 71.8±5.6 ky to after 26.5±2.5 ky corresponding with the maximum ice extent (MIE) during the LGC and subsequent glacial stabilization at 30.3±1.7 – 36.2±2.2 ky. The sediment infill was produced by water ponded in the cave coeval with the presence of glacial ice blocking the cave entrance. The cave clastic sequence includes channel, slackwater and backswamp facies, interpreted to result from pulses of sediment-laden water flow under vadose and phreatic flow regimes. The cave sediment’s mineralogical composition points to an exogenous source associated with glacial till sediments overlying the hillslope above the cave and along the Ara River valley. The palynological results obtained from the cave sediments s

Hillslopes represent areas of predominant denudation and constitute the transition and trajectory to floodplains; they play a crucial role in understanding the longterm landscape evolution of desert environments. However, although hillslope processes are known to be very slow or even stagnant in (hyper-) arid environments, process mechanisms under the virtual absence of water are poorly understood, and process rates are essentially unknown. Based on irrigation experiments, different monitoring techniques including drone-based high-resolution digital elevation models, geomorphological, stratigraphical, geochronological (OSL), sedimentological and geochemical investigations, as well as mu CT scans of sediment cores, this contribution presents detailed insights into the chronostratigraphy of tongue-shaped, 50 m-long and 30 m-wide fine sediment lobes located along a 10-30 degrees steep thrust-related slope east of the Salar Grande (Atacama, Chile). Irrigation experiments were performed to gain insights into precipitation thresholds for surface runoff and hillslope dynamics. Although artificial rainfall intensities were similar to 46 mm/h, infiltration was 100%, and the experiments did not initiate surface runoff or (detectable) slope material displacements. In addition, a distinct stratigraphic pattern with buried paleo-surfaces and paleo-biological surface crusts suggests increased hillslope activity during the late Pleistocene, potentially driven by changes of (fog-induced) humidity, salt-related shrink and swell processes, or paleo-seismic activity. While a variety of geo-bio-archives document periods of increased precipitation in the Andean parts of the Atacama Desert throughout the Quaternary, evidence for contemporaneous paleoclimatic changes from areas disconnected to Andean precipitation fluctuations (i.e., the Coastal Cordillera) is scarce. In this regard, the investigated landforms potentially represent one of only few sediment records recording paleoclimatic

Geological records indicate that the hyper-aridity in the Atacama Desert has prevailed since at least the mid-Miocene, with shorter periods of increased humidity punctuating long-term aridity. The 7-m-high accumulation of colluvial sediments at the Salar Grande (21 degrees S/70 degrees W) studied here provides a key palaeoclimate record to understand hillslope dynamics and its relation to humid periods. While 1 degrees Be surface exposure ages point to long-term surface stability of the flat upslope surface, a combination of humidity-driven soil creep, overland flow and soil creep related to seismic shaking, caused denudation of the hillslope and accumulation of several metres of colluvium over much shorter timescales during the last 130 ka. A robust chronology for the hillslope sediments has been established by using Infrared Stimulated luminescence (pIR-IR225 protocol) on K-feldspar extracts from nine samples collected within the accumulation. A series of tests has been carried out to confirm the suitability of the method. The estimated ages indicate accelerated sedimentation at 35-80 ka, and 100-130 ka, which are interpreted as periods with more humid climate conditions than present. These findings agree with climate variations in the hyper-arid Atacama indicated by the activity of coastal alluvial fans and river catchments.

Two contiguous alluvial valleys (Maria and Guadalupe sectors) of the upper Guadalentin River (SE Spain) show distinct Holocene alluvial architecture (cut-and-fill, nested and stepped fill terraces), revealing a strong control of valley morphology and bedrock barriers on sediment delivery, storage and preservation. The headwater valley (Maria sector) preserves four morphosedimentary alluvial units corresponding to two palaeogeographic stages. Morphosedimentary unit (MSU1), the most extensive, is a major depositional valley infill dominated by sand and silt texture, showing three stratigraphic sets dated 9000-8500, 5300-4800, 4000-3000 cal BP. This vertically stacked alluvial accumulation occurs upstream of a narrow bedrock channel, that limited sediment connectivity with the downstream Guadalupe sector. Between 3000 and 2350 cal BP, a 15-m deep incision on MSU1 occurred, and subsequent cut-and-fill cycles generated three alluvial terraces dated at 2350-1900 cal BP (MSU2), 1800-700 cal BP (MSU3), and post-400 years (MSU4). In the downstream valley (Guadalupe sector), six flights of alluvial terraces (MSUg1 to MSUg6) were formed by episodic aggradation and quasi-continuous incision, in response to baselevel changes of the lower Guadalentin River during the Holocene. Alluvial chronologies in these two contiguous valleys show out-of-phase sedimentation periods under low connectivity conditions (9-3 ka), and in-phase cut-and-fill cycles after valley re-connection (post-3.0 ka). The late Holocene alluvial activity periods also coincide with morpho-stratigraphic data from the lower Guadalentin, indicating that fluvial connectivity throughout the catchment was only completed in the late Holocene.

Two contiguous alluvial valleys (Maria and Guadalupe sectors) of the upper Guadalentín River (SE Spain) show distinct Holocene alluvial architecture (cut-and-fill, nested and stepped fill terraces), revealing a strong control of valley morphology and bedrock barriers on sediment delivery, storage and preservation. The headwater valley (Maria sector) preserves four morphosedimentary alluvial units corresponding to two palaeogeographic stages. Morphosedimentary unit (MSU1), the most extensive, is a major depositional valley infill dominated by sand and silt texture, showing three stratigraphic sets dated 9000–8500, 5300–4800, 4000–3000 cal BP. This vertically stacked alluvial accumulation occurs upstream of a narrow bedrock channel, that limited sediment connectivity with the downstream Guadalupe sector. Between 3000 and 2350 cal BP, a 15-m deep incision on MSU1 occurred, and subsequent cut-and-fill cycles generated three alluvial terraces dated at 2350–1900 cal BP (MSU2), 1800–700 cal BP (MSU3), and post-400 years (MSU4). In the downstream valley (Guadalupe sector), six flights of alluvial terraces (MSUg1 to MSUg6) were formed by episodic aggradation and quasi-continuous incision, in response to baselevel changes of the lower Guadalentín River during the Holocene. Alluvial chronologies in these two contiguous valleys show out-of-phase sedimentation periods under low connectivity conditions (9–3 ka), and in-phase cut-and-fill cycles after valley re-connection (post-3.0 ka). The late Holocene alluvial activity periods also coincide with morpho-stratigraphic data from the lower Guadalentín, indicating that fluvial connectivity throughout the catchment was only completed in the late Holocene.

Olduvai Gorge (Tanzania) is a key site for the study and comprehension of human evolution in East Africa. However, the origin of Homo sapiens and the Middle Stone Age have been poorly understood in the Gorge thus far. In this study, we present the dating, taphonomic, technological and typological analyses of the lithic industry and faunal remains excavated at the Victoria Cabrera Site (VCS) during the 2017 fieldwork season. The stratigraphic sequence of the site contains several levels of fluvial origin, some of them with lithic and faunal remains. Most remains (lithics and bones) are affected by rounding processes. Infrared stimulated luminescence (IRSL) dating has provided ages between 90 and 70 ka BP for these layers that can be related to the Marine Isotope Stage 5a. Lithics are scarce and the dominant raw materials are Naibor Soit quarzite and basalt, followed by phonolite, chert and quartz as the most common raw materials. The lithic technology is based on the production of flakes obtained from prepared cores, with the discoid method and, to a lesser extent the Levallois method being the most frequently used. The retouched blanks are described as “substratum” or “domestic” tools (sidescrapers, notches or denticulates). There is just one heavy duty piece and points are absent. The faunal assemblage includes Alcelaphinae, Antilopinae and Equidae. The major parts of the unidentified faunal remains are size 3 ungulates, followed by carcasses of size 2 and size 4 species. We cannot relate lithic and bones because no cut marks or percussion marks have been identified and carnivore action is scarce. In sum, VCS represents the first accurately dated Middle Stone Age site, with lithic and faunal remains in Olduvai Gorge., Ministerio de Economía y Competitividad (MINECO)/FEDER, Fundación PALARQ, Instituto de Patrimonio Cultural de España, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

In Sierra Nevada (southern Spain), the highest mountain range in southern Europe, the application of an ancestral Integrated Water Resources Management system (IWRM), based on the conjunctive use of groundwater and surface water, provides water resources for irrigation and supply in the driest months of the year in this semiarid mountain region. Meltwater is derived from the headwaters of the mountain streams and rivers through a set of uncoated channels excavated in the ground (locally known as acequias de careo) to infiltrate at the upper part of the valleys. Water infiltrated along the acequias de careo slowly flows down the hillsides, through the weathered zone of the hard rock aquifer and the glacial and periglacial sediments. The recharge accomplished through this Managed Aquifer Recharge technique (MAR) activates numerous springs located halfway down the hillside and increases the base flow of the rivers. In this study, focused on a careo channel located on the southern slope of Sierra Nevada called Acequia de El Espino, different archaeological, sedimentological, geophysical and hydrogeological techniques are applied to determine the age and the efficiency of this ancestral example of a MAR and IWRM system. Results suggest that the acequias de careo may be the oldest MAR system in Europe, and that this MAR technique could be applied in other high mountain alpine watersheds to mitigate the effects of climate change., Ministerio de Ciencia e Innovación (España), Junta de Andalucia, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

Olduvai Gorge (Tanzania) is a key site for the study and comprehension of human evolution in East Africa. However, the origin of Homo sapiens and the Middle Stone Age have been poorly understood in the Gorge thus far. In this study, we present the dating, taphonomic, technological and typological analyses of the lithic industry and faunal remains excavated at the Victoria Cabrera Site (VCS) during the 2017 fieldwork season. The stratigraphic sequence of the site contains several levels of fluvial origin, some of them with lithic and faunal remains. Most remains (lithics and bones) are affected by rounding processes. Infrared stimulated luminescence (IRSL) dating has provided ages between 90 and 70 ka BP for these layers that can be related to the Marine Isotope Stage 5a. Lithics are scarce and the dominant raw materials are Naibor Soit quarzite and basalt, followed by phonolite, chert and quartz as the most common raw materials. The lithic technology is based on the production of flakes obtained from prepared cores, with the discoid method and, to a lesser extent the Levallois method being the most frequently used. The retouched blanks are described as “substratum” or “domestic” tools (sidescrapers, notches or denticulates). There is just one heavy duty piece and points are absent. The faunal assemblage includes Alcelaphinae, Antilopinae and Equidae. The major parts of the unidentified faunal remains are size 3 ungulates, followed by carcasses of size 2 and size 4 species. We cannot relate lithic and bones because no cut marks or percussion marks have been identified and carnivore action is scarce. In sum, VCS represents the first accurately dated Middle Stone Age site, with lithic and faunal remains in Olduvai Gorge.

Modelling experiments of drainage events from proglacial lakes of the Río Baker catchment (central Patagonia, 46–48 ⁰S) indicate that Atlantic-Pacific drainage reversals may have caused freshwater forcing of regional climate. However, much of the region remains unmapped in detail and available geochronological data is equivocal, leading to multiple published palaeolake evolution models. We evaluate these models through new geomorphological mapping from the Baker valley; cosmogenic dating of moraine boulders that demonstrates an Antarctic Cold Reversal ice readvance that blocked drainage through the Río Baker; an altitudinal-based review of published geochronology; and regional analysis of shoreline glacio-isostasy and palaeolake levels. We use these datasets to present a new regional palaeolake evolution model underpinned by Bayesian age modelling. We demonstrate that 10 km of freshwater was released to the Pacific over at least 6 drainage events from before 15.3–15.0 cal yr BP to the early Holocene. The final stages of lake drainage involved catastrophic flooding along the Baker valley, evidenced by high magnitude flood landforms such as boulder bars, likely caused by failure of large valley floor moraine dams. We place these drainage events in the context of Late Quaternary meltwater pathways associated with advance/retreat of the Patagonian Ice Sheet and early human occupation across the region. Although broad patterns of ice retreat and lake formation may be similar across Patagonia, driven by Southern Hemisphere palaeoclimate, regional topographic settings likely resulted in spatial and temporal heterogeneity of Atlantic-Pacific drainage reorganisation across southernmost South America.

The southern North Sea is a particularly important area for understanding the behaviour of the British-Irish Ice Sheet (BIIS) during the last glacial cycle. It preserves a record of the maximum extent of the eastern sector of the BIIS as well as evidence for multiple different ice flow phases and the dynamic re-organisation of the BIIS. However, to date, the known ice sheet history and geochronology of this region is predominantly derived from onshore geological evidence, and the offshore imprint and dynamic history of the last ice sheet remain largely unknown. Using new data collected by the BRITICE-CHRONO project this paper explores the origin and age of the Dogger Bank; re-assesses the extent and age of the glaciogenic deposits across the shallow areas of the North Sea between the Dogger Bank and the north Norfolk coast and; re-examines the dynamic behaviour of the BIIS in the southern North Sea between 31.6 and 21.5 ka. This paper shows the core of the Dogger Bank to be composed glaciolacustrine sediment deposited between 31.6 and 25.8 ka. Following its formation the western end of the Dogger lake was overridden with ice reaching ∼54°N where the ice margin is co-incident with the southerly extent of subglacial tills previously mapped as Bolders Bank Fm. This initial ice override and retreat northwards back across the Dogger lake was complete by 23.1 ka, but resulted in widespread compressive glaciotectonism of the lake sediments and the formation of thrust moraine complexes. Along the northern edge of the bank moraines are on-lapped by later phase glaciolacustrine and marine sediments but do not show evidence of subsequent ice override. The shallow seafloor to the west and southwest of the Dogger Bank records several later phases of ice advance and retreat as the North Sea Lobe flowed between the Dogger Bank and the Yorkshire/Lincolnshire coasts and reached North Norfolk. New optically stimulated luminescence (OSL) ages from Garrett Hill on outwash limit the arr

This paper provides a new methodological approach to analyse secular patterns of flooding (magnitude and frequency) from sedimentary evidence (palaeofloods), taking into account changes in channel geometry, and their links to historical environmental changes and the inherent social and demographic evolution within the catchment. A case study analysis was focused in Rambla de la Viuda (drainage area of 1500 km2) whose stream flow is related to extreme rainfalls. A 500 years sedimentary archive was reconstructed from eight stratigraphic profiles comprising continuous sequences of slackwater flood deposits interbedded with episodic colluvial and edaphic horizons. Discharge estimates associated to sedimentary flood evidences were obtained from one-dimensional hydraulic modelling. The stratigraphic units were sampled to characterise their geochemical and paleobotanical (phytoliths) contents. Palaeoflood chronology was obtained from radiocarbon and luminescence (OSL) dating, supported by documentary data (written historical documents). A high frequency and high magnitude palaeoflood period took place during the 15th-middle 16th century, which seem to correlate in time with general wetter conditions. Three short-term environment stability conditions (land use and climatic) also made possible the development of three paleosols. The lowest flood magnitude and discharges in the sedimentary record was found between the mid-17th to mid-18th centuries, under prevailing drier environmental conditions. Episodic high magnitude flooding took place at late 18th century, correlating in time with palaeovegetation and geochemical evidences of important changes on land use (deforestation and grazing). Poorer developed soils were found at upper stratigraphic sequences (19th century) characterised by thick units of colluvium deposits, usually culminating sequences of short-lived continuous slackwater flood units. Despite of the potential human influence (land-use) on soil hydrology, the lo, Ministerio de Economía y Competitividad (MINECO), CSIC PIE Intramural, Fundación Biodiversidad (MAPAMA), Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

This paper provides a new methodological approach to analyse secular patterns of flooding (magnitude and frequency) from sedimentary evidence (palaeofloods), taking into account changes in channel geometry, and their links to historical environmental changes and the inherent social and demographic evolution within the catchment. A case study analysis was focused in Rambla de la Viuda (drainage area of 1500 km2) whose stream flow is related to extreme rainfalls. A 500 years sedimentary archive was reconstructed from eight stratigraphic profiles comprising continuous sequences of slackwater flood deposits interbedded with episodic colluvial and edaphic horizons. Discharge estimates associated to sedimentary flood evidences were obtained from one-dimensional hydraulic modelling. The stratigraphic units were sampled to characterise their geochemical and paleobotanical (phytoliths) contents. Palaeoflood chronology was obtained from radiocarbon and luminescence (OSL) dating, supported by documentary data (written historical documents). A high frequency and high magnitude palaeoflood period took place during the 15th-middle 16th century, which seem to correlate in time with general wetter conditions. Three short-term environment stability conditions (land use and climatic) also made possible the development of three paleosols. The lowest flood magnitude and discharges in the sedimentary record was found between the mid-17th to mid-18th centuries, under prevailing drier environmental conditions. Episodic high magnitude flooding took place at late 18th century, correlating in time with palaeovegetation and geochemical evidences of important changes on land use (deforestation and grazing). Poorer developed soils were found at upper stratigraphic sequences (19th century) characterised by thick units of colluvium deposits, usually culminating sequences of short-lived continuous slackwater flood units. Despite of the potential human influence (land-use) on soil hydrology, the lo

hree-dimensional paleoseismology in strike-slip faults with slip rates less than 1 mm per year involves a greatmethodological challenge. We adapted 3D trenching to track buried channels offset by the Alhama de Murciaseismogenic left-lateral strike-slip fault (SE Iberia). A fault net slip of 0.9 ± 0.1 mm/yr was determined usingstatistical analysis of piercing lines for one buried channel, whose age is constrained between 15.2 ± 1.1 kaand 21.9–22.3 cal BP. This value is larger and more accurate than the previously published slip rates for thisfault. The minimum number offive paleo-earthquakes identified since the deposition of dated layers suggestsa maximum average recurrence interval of approximately 5 ka. The combination of both seismic parametersyields a maximum slip per event between 5.3 and 6.3 m. We show that accurately planned trenching strategiesand data processing may be key to obtaining robust paleoseismic parameters in low seismicity ares, Ministerio de Ciencia e Innovación, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

Three-dimensional paleoseismology in strike-slip faults with slip rates less than 1 mm per year involves a great methodological challenge. We adapted 3D trenching to track buried channels offset by the Alhama de Murcia seismogenic left-lateral strike-slip fault (SE Iberia). A fault net slip of 0.9 ± 0.1 mm/yr was determined using statistical analysis of piercing lines for one buried channel, whose age is constrained between 15.2 ± 1.1 ka and 21.9–22.3 cal BP. This value is larger and more accurate than the previously published slip rates for this fault. The minimum number of five paleo-earthquakes identified since the deposition of dated layers suggests a maximum average recurrence interval of approximately 5 ka. The combination of both seismic parameters yields a maximum slip per event between 5.3 and 6.3 m. We show that accurately planned trenching strategies and data processing may be key to obtaining robust paleoseismic parameters in low seismicity areas.