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The present study attempts to ascertain the sediment provenance of around 6.5-m thick palaeochannel sediment exposed in the vicinity of the Ghaggar–Hakra river system of the alluvial plains of the Haryana state of India. The major element geochemistry indicates that the sediments are arkosic in nature, dominated by quartz, K-feldspar, micas, plagioclase, and clay minerals (chlorite, illite, and a very less amount of montmorillonite). The CIA (chemical index of alteration) values ranged between 63 and 77, indicating moderate degrees of chemical weathering. REE plots show that the Eu anomaly is negative for average Bhor Saidan samples similar to PAAS and UCC, suggesting that they could have been deposited in the foreland basin after being originally produced from differentiated silicic and/or recycled sedimentary sources; nonetheless, a little positive Eu anomaly in the chondrite normalised plot is the result of feldspar and arkosic nature of sediments indicating higher levels of physical over the chemical weathering. Mostly the samples are from Siwaliks. Optically stimulated luminescence (OSL) dating suggests that the sediments are ~11 ka old. Further, the palaeochannel is being incised ~3.3 ka and younger sediments are stratigraphically deposited at lower levels. The discriminant function plots (Roser and Korsch 1988) of sediment samples exhibited that they were deposited in a passive margin setting and came from the interior of cratons or a quartzose sedimentary orogenic terrain. The present work done on the geochemistry of the sediments of a palaeochannel present in the alluvial plains will work as a dot on the map to connect the history of the river drainage system of the area in future studies. [ABSTRACT FROM AUTHOR]

Groundwater investigation in Thar Desert is a challenging task due to low rainfall pattern and limited recharge. In search of an alternate source of drinking water, satellite remote sensing technique has been used in delineation of palaeochannel (PC) in parts of Rajasthan. Analysis of temporal satellite images (1995–2016) show the signature of PC with increasing vegetation anomaly in an elevated terrain. Validation of the PC and its groundwater potential were demonstrated using land use land cover statistics, High-resolution Electrical Resistivity Tomography (HERT) and drilling data. 2D resistivity tomograms show that the PC aquifer is a low resistivity zone (7.98–53.6 Xm), characterized by thick alluvium at 26 m depth. Based on the integrated analysis of satellite data and geospatial maps it has been inferred that this ancient fluvial channel (PC) has been rejuvenated due to groundwater recharge from the canal water from the north, after commissioning of IGNP canal in 1992. [ABSTRACT FROM AUTHOR]

Remote Sensing technique with multi-sensor satellite images is found to be a useful tool in delineation of the palaeochannel network in arid to semi-arid regions in India. Principal Component Analysis method with fused images (optical and microwave data) shows a wide N-S trending Sutlej Palaeochannels (SPC) and narrow NE-SW trending palaeochannels in central Punjab. High-resolution Electrical Resistivity Tomography (HERT) survey and litholog data analysis provide good groundwater prospect zone of the palaeochannel. Interpretation of 2D resistivity tomograms with Wenner-Schlumberger method exhibit a thick zone of low resistivity layer (saturated coarse-grained sand) at a depth of 40 m. Integrated geo-tectonic study provides clue that the river migration of Sutlej River from N-S to E-W direction was due to a major tectonic upliftment in the Himalaya. Geochronological data analysis indicates that the avulsed channel of SPC was the main course of old Ghaggar River, linked to the ‘Lost Saraswati River’ in northwest India. [ABSTRACT FROM AUTHOR]

Abstract Identification of the diverse channel patterns of meander‐bend migration is essential when reconstructing the historical evolution of sedimentary processes in meandering rivers. However, reconstruction of the spatio‐temporal evolution of ancient meandering fluvial deposits for hydrocarbon exploration is difficult due to the limited research on the patterns and styles of meander‐bend migration. To reconstruct the geomorphologic and sedimentary evolution of subsurface meandering palaeochannels, this study proposes an approach based on combining meander‐bend planforms and cross‐sectional architectural elements of clastic sedimentary successions of ancient meandering rivers. The research was applied to meandering fluvial deposits of the lower Cretaceous Quantou Formation in the north‐eastern Songliao Basin, China. High‐resolution satellite images of modern meandering rivers were used to classify and evaluate the meander‐bend planform transformations of expansion, rotation and contraction (also known as bend tightening, i.e. narrowing of the neck of the meander‐bend showing a tendency towards neck tightening or cut‐off). Major meander‐bend transformations were related to cross‐sectional bedding architecture (i.e. bed dipping or bounding surface), which was identified through well‐log and core characteristics, to construct the migration patterns of subsurface meander‐belt deposits. Integration of well‐log and core analysis from a dense array of wells allowed the stratigraphic architecture of ancient meandering rivers and stacking patterns of fluvial sandbodies to be characterised. Furthermore, major reservoir architectural elements and bounding surfaces of meandering channels were identified. Ultimately, the 3D meandering fluvial architecture was represented on 2D vertical sections so that, planform transformations and the evolutionary processes of point bars and meander bends could be elucidated. Reconstruction of meander‐bend migration is of practical value for deciphering ancient fluvial systems and the development of subsurface fluvial reservoir models.

Merapi Volcano in Central Java, Indonesia, has a high eruption intensity that triggers landscape changes in the form of a river channel evolution. In this paper, the spatial change of river valleys under the influence of sediments deposition in the fluvio-volcanic system is investigated. The data were collected by employing observation, remote sensing image interpretation, literature study and documentation of data from several agencies. The data were analysed using the spatial approach supported by geographic information system (GIS) and remote sensing. The results show that there are many palaeochannels related to fluvio-volcanic processes from the southern to the western sectors of the Merapi volcanic foot. Palaeochannels are mainly distributed next to the main river valleys. This condition correlates with the contributions of the Merapi eruptions. The palaeochannel distribution patterns cluster radially following the distribution pattern of the river valleys. The process that plays the most important role in the evolution of palaeochannels is the deposition of lahar. In sum, this research shows that volcanic activities over a long period of time have provided great and important contributions that have driven the landform evolution. The various changes that occur also reveal the unique morphological characteristics, showing the influence of the volcanic processes.

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Identification of the diverse channel patterns of meander‐bend migration is essential when reconstructing the historical evolution of sedimentary processes in meandering rivers. However, reconstruction of the spatio‐temporal evolution of ancient meandering fluvial deposits for hydrocarbon exploration is difficult due to the limited research on the patterns and styles of meander‐bend migration. To reconstruct the geomorphologic and sedimentary evolution of subsurface meandering palaeochannels, this study proposes an approach based on combining meander‐bend planforms and cross‐sectional architectural elements of clastic sedimentary successions of ancient meandering rivers. The research was applied to meandering fluvial deposits of the lower Cretaceous Quantou Formation in the north‐eastern Songliao Basin, China. High‐resolution satellite images of modern meandering rivers were used to classify and evaluate the meander‐bend planform transformations of expansion, rotation and contraction (also known as bend tightening, i.e. narrowing of the neck of the meander‐bend showing a tendency towards neck tightening or cut‐off). Major meander‐bend transformations were related to cross‐sectional bedding architecture (i.e. bed dipping or bounding surface), which was identified through well‐log and core characteristics, to construct the migration patterns of subsurface meander‐belt deposits. Integration of well‐log and core analysis from a dense array of wells allowed the stratigraphic architecture of ancient meandering rivers and stacking patterns of fluvial sandbodies to be characterised. Furthermore, major reservoir architectural elements and bounding surfaces of meandering channels were identified. Ultimately, the 3D meandering fluvial architecture was represented on 2D vertical sections so that, planform transformations and the evolutionary processes of point bars and meander bends could be elucidated. Reconstruction of meander‐bend migration is of practical value for deciphering ancient fluvial systems and the development of subsurface fluvial reservoir models. [ABSTRACT FROM AUTHOR]

Identification of palaeochannels is vital to address the growing demand for groundwater in developing nations like India. The Damodar Fan Delta (DFD) located in the eastern part of India exhibits many palaeochannels due to the dramatic change in the lower course of the Damodar River. The present study has identified six major palaeochannels from Landsat 8 OLI images (30 m), Sentinel radar data (10 m) and Google earth using various image processing techniques such as multi-sensor fusion, normalized difference water index, normalized difference vegetation index and principal component analysis using ArcGIS 10.4.1, QGIS 3.8.1, ENVI 5.1 and SNAP (7.0) software. The results show that all the major palaeochannels have originated from the lower Damodar River due to their morpho-tectonic changes in the historical record and flow in radiating patterns towards the northeast, east, southeast and south directions. Moreover, numerous small palaeochannels have been traced in the northern and the southern parts of the study area. The study reveals that the optical data provides better information related to surface configurations while the SAR data portrays the near-surface features of the study more effectively. The identification and distribution of palaeochannels have been validated using surface expressions measured by the cross-profiles and sub-surface imprints from the borehole litholog data. Thus, using the remote sensing data coupled with field survey data can provide good information about the changes in the palaeo-landscape of the DFD including unfolding the ancient course of the Damodar River, which may play an important role in augmenting groundwater resources in the semi-critical community development (C.D.) blocks of the DFD. [ABSTRACT FROM AUTHOR]

This study presents the palaeo-botanical record from the central part of Žitný Ostrov Island on the Danubian Lowland in Slovakia. The record spans almost the entire Holocene period and provides evidence that the wetland species Cladium mariscus (Cyperaceae) was present in this region as late as the Greenlandian period. In addition, the combination of C. mariscus and Carex elata beds were most likely an important part of the littoral zone vegetation during that period. Our investigations are based on plant macro-remain analysis, radiocarbon dating and physical sedimentary analysis of the former Danube side channel. The palaeo-channel infill active in the Late Pleistocene reflects complete hydroseral succession of a terrestrialised palaeo-lake. The earlier of two possible hiatuses in the fossil record was likely associated with a disturbance which caused Cladium mariscus to disappear from the local plant spectra. The most likely drivers of C. mariscus' decline are a climate change of 8.6 cal ka BP associated with water fluctuations and the local habitat alteration to an eutrophic environment. These are discussed herein together with the isolated scattered populations surviving in the surrounding micro-region throughout the Meghalayan period. Finally, there are only two known remaining C. mariscus sites in the Žitný Ostrov Island area, and the key modern driving factor was the dramatic water regime changes in 19–20th Century caused by anthropogenic impact. These were caused by the construction of drainage canal systems and the transition from alluvial meadows to agricultural land. [ABSTRACT FROM AUTHOR]

The Assi river in Varanasi, Uttar Pradesh, India, is now a small, local, ephemeral floodplain tributary of River Ganga, with a length of about 8 km and catchment area of about 22 km2. It has also turned into a filthy drain. There are evidences in the form of palaeochannels, through patterns of water bodies and settlements along them, to suggest the origin of Assi river near Allahabad flowing through a distance of about 120 km up to Varanasi to meet the Ganga. There is also the possibility that Assi started as a takeoff from River Ganga and flowed as a Yazoo stream. Through on-screen digitization from high and medium-resolution remote sensing data - BHUVAN and Google Earth, CORONA aerial photographs, IRS P6 LISS-IV, Landsat 1, 3, 5, 7, 8 - and a number of cross profiles from SRTM 30 m digital elevation model (DEM), palaeochannel of Assi has been delineated. Also, a 1 m DEM was generated for the present Assi catchment area from about 5000 DGPS points to present proof that the present Assi is a misfit in once a wider valley shaped by heavy discharge coming from a greater length of channel and a larger catchment area. [ABSTRACT FROM AUTHOR]

Climatic oscillations occurring during the Pleniglacial and Lateglacial periods are generally associated with several changes in fluvial morphology and processes. This study investigated two reaches of the Cher River basin (Noyers-sur-Cher and Thénioux) regarding morphological adjustments during the Lateglacial period and the early Holocene. Transitions from the Pleniglacial to the Lateglacial and from the Lateglacial to the early Holocene (ca. 14,700–11,500 cal. BP) are considered as interesting study cases because it consists of rapid and abrupt climate oscillations generally clearly recorded in current floodplains. The sites studied are located in the Cher River floodplain, which is one of the main tributaries of the Loire River. Several investigations have been conducted in the main valley, but few of them specifically focused on geomorphological evolutions of medium-sized catchments such as tributaries of the Loire River. Therefore, we examined this specific period through investigations recently conducted in the middle valley of the Cher River. This study aimed to (1) provide a geomorphological approach to fluvial adjustments during the Lateglacial from cases located in lowland areas of a medium-sized basin and (2) analyse the spatio-temporal variability of fluvial responses. Assessment of geomorphological trajectories of the two reaches studied highlights that fluvial metamorphosis occurring during the Lateglacial and early Holocene seems to be characterised by lateral readjustments and a low signal of morphological instability (shallow incision and aggradation processes, slow and progressive change in channel morphology). This observation is enhanced by the comparison with known geomorphological evolution patterns of adjacent basins. The intrinsic components of the Cher basin such as slope and valley width were considered as explanatory factors for the lack of morphogenetic processes. In addition, the geographical location of the reaches studied may also have led to a moderated expression of climate forcing. Indeed, the elevation as well as the north– south and east–west gradients may contribute to the low level of geomorphological adjustments in response to these climatic oscillations. This gradient could also have support this the fluvial response because of the weakly developed loess cover, which may have limited the fine sediment supply and the aggradation of the valley bottom. [ABSTRACT FROM AUTHOR]

Defining reference conditions is a crucial element in quantifying the extent of anthropogenic modification and for identifying restoration targets in riverine ecosystems. Despite palaeoecological approaches being widely applied in lakes to establish reference conditions, their use in lotic ecosystems remains limited. In this study, we examine contemporary, historical (1930 and 1972), and palaeoecological macroinvertebrate biodiversity and biomonitoring scores in Eastburn Beck, a headwater tributary of the River Hull (UK) to determine if palaeoecological approaches can be used to characterize lotic system reference conditions. Palaeoecological samples comprised a greater gamma diversity (18 taxa) than contemporary samples (8 taxa), samples taken in 1972 (11 taxa) and 1930 (8 taxa). Palaeoecological samples supported taxonomically different Gastropoda, Trichoptera, and Coleoptera (GTC) communities compared with contemporary and historical samples (1930 and 1972). Results from biomonitoring indices using the GTC community indicated that the palaeochannel had (a) similar invertebrate biological quality, (b) a less energetic flow regime, and (c) increased fine sediment deposits compared with the contemporary channel. The results clearly illustrate that palaeoecological data can provide a suitable method to characterize reference conditions for lotic habitats. However, it is important to recognize that faunal data from palaeochannel deposits provide a short‐term "snapshot" of the conditions within the river immediately prior to its hydrological isolation. River restoration activities should therefore draw on multiple lines of evidence, including palaeoecological information where possible, to characterize a range of reference conditions to reflect the highly dynamic nature of lotic ecosystems. [ABSTRACT FROM AUTHOR]

Abstract This study derives a new function describing the relationship of channel bankfull discharge (Q bf) to channel width in modern rivers of the Murray-Darling Basin (MDB) of southeastern Australia and applies this to dated palaeochannels of seven rivers to quantify late Quaternary discharge history in this important basin. All rivers show high MIS3 and MIS2 Q bf , declining in the Holocene. The Q bf of modern MDB rivers is correlated with total catchment precipitation but comparison with palaeochannel Q bf estimates shows that while enhanced runoff efficiency is necessary to account for much larger late Pleistocene palaeochannels, either lower or higher precipitation rates could have prevailed. A strong association between relative palaeo- Q bf enhancement and temperature suggests a temperature-mediated mechanism controlling river discharge, such as the fraction of precipitation stored as snow and thawing in spring, the enhancement of orographic rainfall, or CO 2 feedbacks with vegetation cover. Significantly enhanced MIS3 Q bf requires an additional mechanism, such as increased rainfall. These findings are consistent with others that increased moisture availability was associated with past colder climates, although this was not necessarily the result of enhanced precipitation. Highlights • Dated palaeochannels of the Murray-Darling basin, Australia, reveal late Quaternary hydrological history. • A regime equation based on modern rivers is used to predict palaeo-discharge. • Discharge of MIS2 and MIS3 palaeochannels was 3–270 times equivalent modern rivers. • MDB palaeochannel discharge follows Antarctic temperature, which determines catchment runoff. • Relatively larger MIS3 MDB palaeochannels require additional moisture sources. [ABSTRACT FROM AUTHOR]

This paper reports the first reconstruction of storm-generated late Holocene and historical river floods in the North Island of New Zealand. The sedimentary infills of nine palaeochannels were studied in the lower alluvial reaches of the Manawatu River. Floods in these palaeochannels were recorded as a series of sand-rich units set within finer-grained fills. Flood chronologies were constrained using a combination of radiocarbon dating, documentary sources, geochemical markers, and palynological information. Flood units were sedimentologically and geochemically characterised using high resolution ITRAX™ X-Ray Fluorescence (XRF) core scanning and laser diffraction grain-size analysis. The longest palaeoflood record extends back ca.3000 years. The temporal resolution and length of the Manawatu record reflects accommodation space for fluvial deposits, channel dynamics and mobility, and high sediment supply. Floods that occurred in the Manawatu during the mid-1800s at the time of European land clearance and in the first decade of the twentieth century appear to be among the largest recorded in the last 3000 years. [ABSTRACT FROM AUTHOR]

The start of Nile-type trans-Saharan drainage systems in NE Africa during the Cenozoic is disputed. Stratigraphical and sedimentological data in Egypt are partly in conflict with the uplift history of potential source areas of water and sediment in East Africa. Here, we investigate outcrops of the Wadi Awatib Conglomerate in Sudan that provide the first evidence of northerly flowing Neogene rivers in the region. Dimension and relief of basal erosion surfaces, overall geometry of deposits and palaeocurrent indicators demonstrate that the deposits represent the fill of northward-oriented incised valleys. The conglomerates were deposited in deep gravel-bed rivers, by hyperconcentrated flows, tractions carpets and gravel bars, primarily during heavily sediment-laden floods of probably monsoonal origin. Stratigraphical and geomorphological relationships show that the deposits are between Eocene and Pliocene in age. Considering the structural history of the region and periods in the Cenozoic with palaeoclimatic conditions suitable for the production and transport of gravels, we hypothesize that the dramatic base-level fall during the Late Miocene Messinian salinity crisis in combination with a favorable palaeoclimate caused the incision of valleys and their subsequent filling with conglomerates. Sea-level change in the Mediterranean Sea and headward erosion of streams that were connected to the Egyptian Nile might have been the primary cause of valley incision and deposition of conglomerates, despite a location far inland from the coastline. We suggest that the deposits document a relatively young Neogene (Messinian to early Pliocene) trans-Saharan river system unrelated to uplift of the Ethiopian Plateau. [ABSTRACT FROM AUTHOR]

In this article we re-visit hypotheses about the changing social and environmental landscapes in southern Central Asia during the late Holocene, specifically giving attention to the transitional period between the archaeologically-defined Late Bronze – Early Iron Age (second half of the 2nd millennium BC) and the numerous documented changes in the archaeological and physio-geographical record during this time. We focus on the northeastern Murghab alluvial fan (Turkmenistan) as a window into this complex period, and examine one aspect of human-environmental dynamics there, namely, the relationship between the location of archaeological sites and mapped ancient watercourses (palaeochannels) through time. Our analysis incorporates nearly 400 new archaeological sites documented in the northeastern Murghab since 2006, which have not previously been included in published models of settlement and/or hydrological dynamics. Our findings suggest the periods of the Late Bronze Age and Early Iron Age (Yaz I) demonstrate two distinct access-to-water practices, which may correlate to different processes of socio-territorial control being implemented. While no single line of evidence can adequately disentangle the complex interconnected processes of environmental and social change, our results lend themselves to integration with the current working knowledge of the local processes of socio-environmental development in the Murghab. The results also fit more broadly within emerging discourse that recognizes the importance of micro-scale processes and adaptation in Eurasian prehistory. [ABSTRACT FROM AUTHOR]

Although commonly found in deserts, our knowledge about inverted relief landforms is very limited. The so-called 'Gravel Body' in the northern Kumtagh Desert is an example of an inverted relief landform created by the exhumation of a former fluvial gravel channel. The common occurrence of these landforms indicates that fluvial processes played an important role in shaping the Kumtagh Desert in the past 151 ka. A physical model is presented to reconstruct the palaeohydrology of these fluvial channels in terms of several measurable parameters including terrain slope, boulder size, and channel width. Combining the calculated palaeoflood depth, the maximal depth of channel bed eroded by wind, and the current height of inverted channels with the age of the aeolian sediments covered by gravels, the local wind erosion rate is estimated to be 0.21-0.28 mm/year. It is shown that wind erosion occurring in the Kumtagh Desert is no more severe than in adjacent regions. Since the modern Martian environment is very similar to that of hyperarid deserts on Earth, and Mars was once subjected to fluvial processes, this study will be helpful for understanding the origin of analogous Martian surface landforms and their causative processes. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Numerous palaeochannels, oxbow lakes and elongated sediment fills in Eastern India, particularly along the lower Ajay River, provide a record of channel shifting during the Late Quaternary. Proper characterization of these features is useful for discussing the dynamic evolution of the river system in the Ajay-Damodar Interfluve region. Remote sensing data, archaeological evidence and sedimentology aid in reconstructing the geomorphic history of the lower Ajay River. Archaeological studies help in calculating the rate and direction of channel migration. The channel migration rate varies from 0.32 to 3.41 m/year in the study area. Bouguer gravity anomalies suggest that the rate of channel migration may be controlled by the density variations of the basement rocks. Furthermore, neotectonics activity played a significant role in the migration of Ajay River towards north-east direction. [ABSTRACT FROM PUBLISHER]

Sandstone-type uranium deposit hosted by reduced feldspathic sandstone sequence of lower part of Cretaceous Mahadek Formation occurs at Lostoin area of Mahadek basin and is confined within a prominent palaeochannel of NNE-SSW trend with flow towards SSW. The channel-fill comprises of about 10 m to 55 m grey to dark grey coloured, reduced, coarse to medium grained feldspathic sandstone along with abundant carbonaceous matter (5 to 15% by visual estimation) and is overlain by 5 m to 80 m of oxidized sub-feldspathic sandstone. Correlatable medium grade (∼ 0.1% UO) uranium mineralization is intercepted in the boreholes aligned along the palaeochannel. Uraniferous solutions generated from the fertile provenance of south Khasi batholith flow through the channel and precipitated uranium at suitable reduction traps. Gentle slope of 2° to 3° of the basement channel facilitated prolonged interaction of uraniferous solution with reductants causing ore grade concentration. It has been envisaged that the control of palaeochannel and palaeobasement topography of the ore body would continue towards the SSW beyond Wahblei river. [ABSTRACT FROM AUTHOR]

The Ner River valley (central Poland) underwent substantial transformation during the Weichselian–Holocene transition as a result of fluvial processes and climate changes, resulting in the establishment of its present shape in the Holocene. A multiproxy study based on organic deposits from a palaeochannel fill (Lutomiersk–Koziówki) shows that after the channel was cut off during the late glacial termination, it became a shallow oxbow, fed by local springs. In the Boreal period, the oxbow lake was also fed by precipitation and became a telmatic environment overgrown by rush and swamp vegetation. Finally, it was covered by overbank deposits. The first flooding phase (9900–9600 cal. BP) was followed by the accumulation of overbank sediments (after 9500 cal. BP) and flooding increased after ca. 9300–9000 cal. BP. Pollen data provide information on the regional vegetation context for local and regional changes. In the Atlantic period, an increase in both summer and winter temperatures is inferred from the pollen data, corresponding to an expansion of thermophilous deciduous forests. While in general, flooding phases of the Early Holocene are poorly recognised in Eastern Europe, the Lutomiersk–Koziówki site may be considered as one of the reference points for this phenomenon in the region. [ABSTRACT FROM AUTHOR]

We studied the alluvial infill preserved on the confluence of Roklanský Potok and Javoří Potok streams by means of geomorphic mapping, geophysical profiling, and sedimentological analyses. The conventional radiocarbon dating and archaeological findings helped to reconstruct evolutionary phases that formed the present landscape of central part of the Bohemian Forest (Šumava in Czech), the Šumavské Pláně plains. The Upper Terrace that fringes the valley is a remnant of Pleistocene gravel infill of the valley. The Lower Terrace and active floodplain formed by Holocene sands are most probably result of increased overbank sedimentation caused by extensive deforestation of upper parts of the catchment during the 18th, 19th, and 20th centuries. Recent evolution of the landscape is characterised by vertical and lateral incision caused by anthropogenic modifications of fluvial regime in the upper parts of the catchment. [ABSTRACT FROM AUTHOR]

The history of the Ner River valley is well documented in Kolonia Bechcice (NKB) palaeochannel sediments. It was cut-off from the riverbed in the Younger Dryas. Its history may be divided into five distinct phases. During the Younger Dryas, the NKB was a relatively deep, oligotrophic water body. From the onset of the Holocene, the lake became a eutrophic, overgrown pond which quickly palludified and transformed into a rich fen with ferns and birches. There is a hiatus in the middle of the Holocene fen stratigraphy. A peat sequence is covered by fluvial silt and sand deposits. The NKB sequence documents the Ner valley as a dynamic system during the Late Glacial and the Holocene. Local ecosystems of this oxbow have remained under a much stronger pressure of climate changes than palaeolakes and wetlands located on uplands in the Łodź region. [ABSTRACT FROM AUTHOR]

We have identified a 230 km long palaeochannel cutting through the sediments of the Obosum Group within the Volta Basin, Ghana. The channel is visible in regional airborne magnetic data as a pair of parallel magnetic anomalies which we interpret to be lateral terrace placer deposits of magnetite or maghemite and show both meandering and braided geometries. The palaeochannel is also visible in the airborne radiometric data for part of its length, as well as in airborne electromagnetic data, where it is marked by a zone of low conductivity. The meanders have a wavelength of around 20 km and together with the 2 km spacing between magnetic anomalies, suggest a major palaeo-river system, of as yet unknown age, although based on published detrital zircon ages for the host sediments and geomorphological arguments it is probably between 509 ± 68 and 45 Ma, and is comparable in size to the modern-day Niger River. Given the known occurrences of alluvial gold and diamonds in Ghana, and the general prospectivity of meandering and braided rivers systems, we believe the region has exploration potential for a range of economically valuable minerals, and could also potentially host a shallow aquifer. [ABSTRACT FROM AUTHOR]