The hydromorphological behaviour in a river confluence zone is examined in classical fluvial geomorphology at the global scale. However, oscillatory confluences of a pair of rivers and related impact on confluence geometry, planform, cross-sectional dynamics with fluvial hydraulics in their historicity are rare in the previous work. Thus, the present study intends to unfold the trajectory development of confluences of two tropical rivers in India (Babla and Bhagirathi) during 1781-2025 based on historical maps, satellite images, and intensive survey data. The study demonstrated asymmetrical developments of the confluence with progressive shifts towards north and east through the piracy of the tributary Babla River by its master channel Bhagirathi River. The frequent changes in the meander geometry (wavelength, radius of curvature, amplitude, sinuosity index, radius/wavelength ratio, meander form and shape indices) in the confluence zones are conspicuous. In the post-confluence phase, some meander loops dwindle while others accentuate. Confluence change largely affects the sediment flux and transport capacity of the river, thereby influencing the river erosion and accretion sequences over space and time. The Acoustic Doppler Current Profiler depicts the velocity profiles with scoured zones in the confluence areas. The cross-sectional morphology portrays vehemently altered river thalwegs during 2020-2025 as a direct consequence of the shifting river mouth. The confluence zones shift in response to a few drivers like litho-stratigraphy and fluvial hydraulics. The progressive shifts towards the east are driven by the erosion permitting sand facies compared to the hard clays-dominated western facies. The Babla channel is narrower than Bhagirathi, and its discharge is only 28% of Bhagirathi's discharge, inducing the progressive shift of the confluence zone towards Babla. The process-based understanding of this investigation would help develop better river management plans.
The lower Alpheios valley hosts one of the most emblematic archaeological landscapes of the Mediterranean world, where long-term environmental dynamics shaped the development and functioning of the sanctuary of Olympia. Understanding the Holocene evolution of the Olympia plain is therefore central to geoarchaeological interpretations of river dynamics, landscape accessibility, and site preservation.Recently, the traditional fluvial interpretation of the Olympia plain has been challenged by a new palaeoenvironmental model invoking a persistent palaeolake. Here, we evaluate the Holocene evolution of the lower Alpheios valley by integrating published chronostratigraphic, sedimentological and palaeoecological datasets within a newly developed basin-scale geomorphological, sediment-budget and regional source-to-sink framework.The stratigraphic record lacks the laterally continuous, consistently fine-grained sedimentary package expected for a long-lived lacustrine basin. It is instead dominated by mixed grain-size assemblages and repeated moderate-to high-energy depositional facies. Sediment-budget analysis reveals a first-order volumetric mismatch between the maximum storage capacity of the proposed palaeolake (∼0.15 × 109 m3) and the ∼2.1–2.5 × 109 m3 of Holocene sediment stored in the Alpheios delta and lower floodplain, exceeding potential lake storage by approximately 14–17-fold. A regional source-to-sink comparison of seven Peloponnesian fluvial systems independently confirms this interpretation, showing that the Alpheios sediment budget is fully consistent with an open fluvial system, whereas the palaeolake scenario would imply anomalously low sediment transfer efficiency outside the regional envelope. Comparative microfaunal and grain-size evidence further demonstrates that assemblages previously interpreted as lacustrine are fully compatible with dynamic floodplain environments. Palaeohydrological reconstruction of the presumed harbour site further indicates that the water levels required by the lacustrine scenario would have flooded large parts of the sanctuary during Antiquity, rendering a harbour interpretation implausible.Geomorphological and lithological constraints preclude long-term natural damming in the Flokas sector, while chronostratigraphic marker horizons point to localised late-Holocene block uplift, offering a parsimonious alternative explanation for elevation offsets and stratigraphic discontinuities previously attributed to lake-level fluctuations. Collectively, these results indicate that the Olympia plain functioned throughout the Holocene as part of an open (unimpounded) fluvial system, with the Alpheios River during Antiquity likely flowing in proximity to the southern margin of the sanctuary rather than along the shore of a persistent lake.
The Ganges Submarine Delta, serving as a crucial link in the "source-sink" system between the Tibetan Plateau and the Bay of Bengal, play an important role in the land-ocean interactions in northeastern Indian Ocean. However, research on the sedimentary processes and response mechanisms to silicate weathering within the Himalayan system remains inadequate. Therefore, based on sedimentological and geochemical characteristics of the sediments of Core BOB-63 in the Ganges Submarine Delta, and in conjunction with AMS 14C dating, this study identifies the sediment sources and reconstructs the evolutionary history of chemical weathering intensity during the mid-Holocene. It indicates that almost all sediments in the study area originated from the Himalayas since 8000 cal yr BP. Integrated geochemical indicators reveal that the chemical weathering process of sediments in the study area can be divided into three stages. Stage I (8000-7000 cal yr BP), during which the transgression process led to rapid transport and deposition of floodplain sediments, resulting in a relatively low intensity of chemical weathering. Stage II (7000-5300 cal yr BP), is characterized by enhanced summer monsoon and northward shift of the maximum rainfall belt. It significantly enhanced the degree of chemical weathering of terrestrial detritus and also increased the input flux of continental material. Stage III (5300-3900 cal yr BP), is marked by southward migration of the maximum rainfall belt and weakening of the Indian Summer Monsoon. It results in a reduced flux of terrestrial detritus into the sea and a decreased chemical weathering intensity. The results indicate that the sea-level controlled the chemical weathering intensity by influencing sediment transport from the floodplain to the Ganges Submarine Delta. Meanwhile, the intensity of the Indian summer monsoon and the movement of the maximum rainfall belt, regulated by the Inter-Tropical Convergence Zone (ITCZ), are the key factors determining the flux and chemical weathering intensity of continental detrital sediments in the study area during periods of high sea level.
Holocene pollen records provide important baselines for understanding long-term vegetation responses to climate variability and human disturbance. Here, we examined Holocene arboreal pollen dynamics across China using arboreal pollen (AP) assemblages from 189 records, integrating AP Z-scores, spatial interpolation, and rate-of-change (RoC) analysis to characterize AP-inferred arboreal representation and arboreal pollen assemblage turnover. Our results show a three-stage national trajectory of AP-inferred arboreal representation, with an early-Holocene increase, a middle-Holocene highstand, and a late-Holocene decline. Spatial interpolation at 9, 6, and 3 ka BP showed pronounced spatiotemporal heterogeneity, with the widest extent of high AP values during the middle Holocene and lower AP values across many regions during the late Holocene. In contrast, RoC remained generally low during the early to middle Holocene but increased after ∼4.2 ka BP, with a further rise during the last ∼1 ka. Regional contrasts were also evident: humid monsoonal regions showed relatively high AP-inferred arboreal representation and comparatively low RoC, whereas monsoon-margin, ecotonal, arid, and high-altitude regions showed stronger late-Holocene variability, higher RoC values, or more frequent peak-flagged intervals. These results indicate that AP-inferred arboreal state and compositional turnover rate provide complementary perspectives on Holocene vegetation change. Long-term hydroclimatic variability likely shaped the broad trajectory of arboreal pollen representation across China, while late-Holocene climatic variability, together with a possible contribution from human land use, may have increased compositional turnover in sensitive regions.
The spread of agriculture marks one of the major ways in which humans transformed the environments of Eurasia during the Holocene. Associated with such agricultural transitions a distinctive form of stone harvesting knife became synonymous with the establishment of early agricultural systems across East and Central Eurasia. Here, we compile evidence for the typology, and chronological distribution of these harvesting knives, in comparison to evidence for cereal crops, providing insights into the cultural and demic diffusion of agricultural practices, which may have implications for the spread of language families.Harvesting knives first occur with millets in the Yangshao Cultures of the Middle Yellow River basin in the latter half of the 5th millennium BCE. Significantly they appear at the end of the domestication episode, replacing stone sickles in some regions. This reflects a shift from pre-domestication cultivation regimes where millets were undergoing domestication, likely harvested semi-green, to one in which enlarged, non-shattering, fully ripened panicles were harvested individually, for which such tools were well suited. Harvesting knives spread with millet agriculture into the Upper Yellow River Valley and the Tibetan Plateau, reaching Kashmir and Swat by the 2nd millennium BCE. This westward movement is hypothesized to correlate with the spread of Sino-Tibetan languages at least into Tibet and Northeast India. Harvesting knives spread south to the Middle Yangtze Basin with millet and rice agriculture, and to southeast China and Taiwan by the 3rd millennium BCE. This southern spread saw cultural diffusion across language families. In the Lower Yangtze stone harvesting knives became exclusively associated with rice agriculture in the Liangzhu and post-Liangzhu Cultures (3300-2000 BCE). To the east harvesting knives did not accompany the initial expansion of millet agriculture from c.3500 BCE into Korea and Primorye, but rather spread into Korea with rice agriculture after 1500 BCE, reaching Japan in the early 1st millennium BCE.
The Last Interglacial (LIG), 130-116 ka, is an excellent analogue for understanding potential future directions of climate under ongoing warming, where precipitation patterns are particularly uncertain. The spatial and temporal patterns of hydroclimate in the Southern Hemisphere (SH) have received less attention than in the Northern Hemisphere. Therefore, this study provides a comprehensive, transparent, and expandable database of hydroclimate-interpretable proxies (related to variations in precipitation and mediated by other controls on moisture availability and/or hydrology) in the SH during the LIG, to serve as an essential point of reference that covers South America, southern Africa and Australia. The compiled proxies are diverse, extracted from near-shore marine sediment archives that received terrigenous-derived material and from terrestrial archives including speleothems and lacustrine sediments. They include elemental ratios, sediment mass accumulation rates, freshwater diatoms, pollen concentrations and assemblages, charcoal, leaf wax stable isotopes, speleothem stable isotopes, lake shorelines and lacustrine sediment physical properties and geochemical characteristics. For the first time, we consider time-windows through the LIG, in comparison with other global scale proxy syntheses that explore LIG average conditions (130-116 ka) or the 127 ka 1000-year timeslice employed in the Palaeoclimate Modelling Intercomparison Project (PMIP). Our three 5000-year times slices 130-126 ka, 125-121 ka and 120-116 ka, allow us to explore how SH hydroclimate evolved through the LIG. Examining intra-interglacial variability is particularly valuable for considering SH summer insolation as a boundary condition through the LIG, where 130-126 ka is low insolation and 120-116 ka is high insolation, rather than focus on globally averaged greenhouse gas concentrations, terrestrial ice volume and sea-level. We provide a model-proxy comparison, employing the PaleoPGEM emulator to generate precipitation anomalies for the LIG relative to the Holocene for those same three 5000-year time-windows. Our model-proxy comparison allows temporally nuanced observations of spatial precipitation patterns, which highlights broad areas of consensus as well as key regional contradictions and offers a more refined understanding of hydrological change across South America, southern Africa and Australia. Our findings have important implications for contextualising future climate change, and highlight the uneven nature of hydroclimate shifts, which is especially important for Australia, southern Africa, and South America, where drylands, which experience negative moisture balance, cover 75–95%, ∼85%, and ∼30% of the land area, respectively.
The vast northern region of the West Siberian Lowlands still has relatively few detailed geological archives for the Late Quaternary, most of which are distributed along the Arctic coast. An extensive section of the Tyiakha River terrace and several neighboring outcrops provide a rich record of sedimentary, cryogenic and soil forming processes located in the inland part of this region. Detailed description together with particle size analysis, morphoscopy of quartz grains and micromorphological observations reveal the set of surface processes responsible for section development, whereas palynological investigations provided a proxy for paleoenvironment. During MIS 3 and possibly beginning of MIS 2, medium-strong cryogenic alluvial sedimentation prevailed. Some eolian reworking is indicated by quartz grain surface microstructures. Signs of palustrine deposition and syn-sedimentary cryohydromorphic soil development were observed in the low-energy alluvial unit corresponding to the end of MIS 3, being consistent with the pollen spectra indicative of tundra-steppe ecosystems. At that, the revealed polygenetic MIS 5 paleosol fragment in the bottom of the section, with contrasting pollen assemblages, was incorporated into younger alluvium in a frozen state. During the coldest phase of MIS 2, alluvial deposition seized, and epigenetic ice wedges developed, which were converted into pseudomorphs filled with gleyic pedosediments at the terminal Pleistocene. The combination of cold alluvium, ice wedge casts, and cryohydromorphic pedosediments was used as a representative stratigraphic unit for MIS 2 in NW Siberia and for stratigraphic correlation of the Tyiakha section with the Late Pleistocene continental geological records of Northern Eurasia.
This study investigates animal husbandry in the Roman and medieval Lagoon of Venice, relying on zooarchaeological evidence. It draws on taxonomic frequencies and ageing data, while placing particular emphasis on biometric analyses. In the Roman period, settlement concentrated in the city of Altino. As in other western regions of the Empire, along the endo-lagoonal coast cattle husbandry played a major role in agricultural work and large-scale meat production; cattle were particularly large and robust, and only culled well into adulthood. In the Early Middle Ages settlement focus shifted to the lagoon islands and animal husbandry practices changed, in part as a consequence of inevitable adaptations to spatial constraints. Animal husbandry now focused on pigs, which could be kept in small spaces, had a flexible diet, and were particularly prolific. Their rearing was probably integrated within the broader local food economy, especially orchard and vegetable cultivations, wildfowling, and fishing, and all these activities permeated community life. Pigs slightly increased in size as a result of herding conditions and possibly selective breeding; the few cattle introduced to the islands from the mainland were considerably smaller than their Roman counterparts, as the pressure to produce agricultural and meat surpluses had been lifted. In the Later Middle Ages, cattle and caprines undergo a further slight decrease in size, although their frequency and importance increase, with the appearance of specialised production, consumption, and redistribution sites. This biometric approach to the reconstruction of animal husbandry in the Roman and medieval Venetian lagoon offers new perspectives on human settlement choices, resource availability, zootechnical knowledge, and the long-term evolution of human-animal-wetland relationships.
Late Quaternary sediments in semi-enclosed bays serve as valuable archives of sea-level fluctuations and shifts in depositional environments. Thus, these regions are ideal for investigating the last glacial-interglacial transition. In this study, we focus on borehole HSZK04B retrieved from the semi-enclosed Kaozhouyang Bay (KZYB), located in the northern coastal region of the South China Sea (SCS). Analyses were conducted based on the lithological and grain size characteristics, chronostratigraphy and microfossil stratigraphy. By comparing its stratigraphic sequence with those of adjacent boreholes, we reconstructed the late Quaternary sedimentary and environmental evolution of KZYB. The results showed that borehole HSZK04B can be divided into seven distinct sedimentary units (U7-U1), corresponding to the Old Red Sand deposits of early MIS 4 (U7), mottled clay deposits from late MIS 4 to early MIS 3 (U6), fluvial deposits of early MIS 3 (U5), marsh deposits from late MIS 3 to early MIS 2 (U4), lacustrine deposits during the last deglaciation period (U3), neritic deposits of the early Holocene (U2), and coastal bay deposits of the late Holocene (U1), respectively. Comprehensive stratigraphic analysis of boreholes in the northern SCS coast revealed that the MIS4 strata were the basal boundary of the Quaternary sequences. Variations in sea level and sedimentation accommodation space governed the development of diverse sedimentary facies within semi-enclosed bays. During the lowstand sea-level phase of the Last Glacial Maximum (LGM), continental deposits were formed. In the subsequent deglacial period, drowned valleys or freshwater lakes emerged, followed by neritic deposits during the early Holocene, and coastal progradational deposits during the late Holocene. This scenario highlights the dominant control of global sea-level fluctuations on sedimentary processes and environmental evolution in semi-enclosed coastal settings, thereby enhancing our understanding of the late Quaternary sedimentation mechanism in such bay environments.
Although loess deposits have been globally mapped and extensively studied, current understanding of their distribution and paleoclimatic significance in Pakistan remain limited. In this study we identified and characterized loess deposits along the Indus River in Pakistan through systematic field work, sampling (top soils and loess sections) and multi-proxy measurements. Based on sedimentary features and bulk grain size distributions, we reveal that, in addition to the previously known loess in the northern highlands, loess deposits of varying thickness are widespread across the Indus Plain. Tentative stratigraphic correlation among three loess sections (TD, BH, ATT) and loess sections in the Kashmir Valley suggests that loess in the northern highlands was dated back to at least 300 ka, while on the Indus Plain, commenced around 60-25 ka (Marine Isotope Stage 3). Pakistani loess exhibits significant regional differences in bulk grain size, paleosol development, magnetic properties, and geochemical characteristics, likely influenced by factors such as the topography, dust sources, and hydrological conditions. The identification and characterization of these loess deposits advance paleoclimate reconstruction efforts, although future work is needed to refine chronology, identify dust sources, select appropriate proxies, and establish regional correlations.
Southwestern Iran occupies a climatically sensitive transition zone between mid-latitude westerlies and low-latitude monsoon systems, yet Holocene paleoclimate reconstructions from loess-paleosol archives remain limited. Here, we present a multi-proxy investigation of a well-preserved loess-paleosol sequence from the Shooshtar area to reconstruct regional climate evolution since 10.2 ka BP. Based on a Bayesian age-depth model constrained by three AMS 14C dates, grain-size distributions, magnetic properties, geochemical elemental ratios, and diffuse reflectance spectroscopy were systematically analyzed. The results reveal two distinct stages of Holocene climate evolution, separated by a major transition at ∼5 ka BP. The Early–Middle Holocene (∼10.2–5 ka BP) is characterized by intensified pedogenesis and increased effective moisture, whereas the Late Holocene is marked by reduced pedogenesis, enhanced aeolian activity, and progressive aridification. Regional comparisons indicate that this transition reflects a large-scale reorganization of atmospheric circulation across West Asia. The regional aridification trend since ∼5 ka is consistent with a decline in winter precipitation across the Mediterranean, which is primarily controlled by westerly-derived moisture supply, and contrasts with the contemporaneous humidification associated with the southwest monsoon. This pattern suggests that Late Holocene drying in the study region was more directly linked to reduced westerly-derived winter moisture. These results underscore the dominant role of westerly circulation in regulating hydroclimatic variability across the semi-arid margins of West Asia.
This presents the findings of a comprehensive pollen analysis conducted on lacustrine sediments from two cores collected from Holocene Lake Faiyum (F1-08 and Howara 1). The Early Holocene sediments are characterized by a rich diversity of aquatic and wetland pollen types, predominantly comprising grasses and bryophytes in the Ricciaceae and Poaceae families. In contrast, the middle Holocene pollen assemblage demonstrates a notable increase in non-indigenous arboreal pollen types, such as Pinaceae and Acanthaceae, relative to indigenous arboreal types. In Late Holocene pollen assemblages, Cyperaceae pollen is found to be abundant, whereas Poaceae and Ricciaceae pollen are comparatively scarce. This observed pattern may indicate a decline in Nile floods and a subsequent reduction in lake levels. As the Faiyum Delta undergoes evolution, a peripheral marshy areas develope due to lowereing lake level.
Tropical island rainforests have long been viewed as marginal environments for Late Pleistocene foragers, particularly during the climatic instability of the Last Glacial Maximum (LGM). Preliminary archaeological evidence from the Inumaki Cave on Biak Island, Indonesian Papua, dating to before, during, and after the LGM provides insights into the timing and nature of human occupation in these environments. It also clarifies an important period of human expansion around northern Sahul and contributes to the sparse Pleistocene record of this region. The evidence consists of stratified faunal remains, marine shellfish, and lithic artefacts recovered from deposits spanning the Late Pleistocene to the early Holocene. The archaeological assemblage indicates episodic human occupation of the cave supported by a broad-spectrum foraging strategy integrating both forest and island resources. These included terrestrial mammals (cuscus and bandicoots, and possibly rats and bats) and reptiles (snakes and possibly lizards), and coastal shellfish. A single tooth from a forest wallaby, dating to after the Terminal Pleistocene, may also reflect translocation or the movement of bone ornaments from northern Sahul. Lithic artefacts made on local limestone reflect flexible responses to restricted access to raw materials in this small island environment. These findings demonstrate the capacity of Late Pleistocene populations to persist in tropical island rainforests during the LGM and refine our understanding of human ecological niche expansion during a period of globally significant climatic and environmental change.
Aeolian sand deposits, formed at the boundary between marine and terrestrial settings, are capable of providing valuable insight into sea-level variations and coastal environmental dynamics. However, the factors controlling aeolian sand deposition and the variations in sediment provenance of aeolian deposits during stadial and interstadial periods remain poorly understood. Accordingly, a comprehensive investigation of aeolian sand deposits was conducted by integrating scanning electron microscopy (SEM) with optically stimulated luminescence (OSL) dating, complemented by multiple proxies. The objective of this study was to examine the sedimentary dynamics, identify the controlling factors influencing sedimentary processes, and elucidate changes in sediment provenance. The microtextures of quartz grains exhibit significant spatial variability from the coast to the inland areas, reflecting a shift in sedimentary dynamics from wave-aeolian interaction to aeolian-dominated transport. OSL dating results reveal episodic accumulation during marine isotope stage (MIS) 3 (41–49 ka), MIS 4 (∼67 ka), and MIS 5 (78–96 ka). During interglacial periods, rising sea levels trigger coastal erosion, transporting large amounts of sediment through wave action and longshore drift, thereby promoting the formation of aeolian deposits. The shortened distance to the shoreline, combined with a higher sediment supply, facilitates the accumulation of aeolian sand further inland. Conversely, during periods of low sea level, the subaerial exposure of the continental shelf was eroded by intense aeolian deflation, resulting in the formation of large volumes of sand fractions that were blown landward by onshore winds. Aeolian sand accumulation predominantly occurs in coastal zones, attributed to the extension of the coastline and post-depositional aeolian reworking. Our findings suggest that sediment supply, modulated by sea-level fluctuations, and monsoon intensity are the primary mechanisms driving aeolian accumulation across different climatic intervals.
