the impact of wallachian settlement on relief and alluvia composition in small valleys of the carpathian mts czech republic abstract the impact of the wallachian settlement on small mountain catchments has been studied at the example of skor ansk and hartisov streams moravskoslezske beskydy mts western outer carpathians between the 16th and the 19th centuries the wallachian people introduced pastoral management originating from the woodless balkans to the forested mid altitude mountain area under study this area was subjected to rapid settlement intense grazing in forests and slash and burn deforestation to assess the geomorphic effects of wallachian activity in the catchments studied grain size structure organic matter content and the plant macrofossil composition of the alluvia forming terrace levels in the mouths of the skor ansk and hartisov streams were analysed radiocarbon dating 137 cs and 210 pb analyses and dendrochronological dating were also applied to determine the age of the alluvia studied the results were compared with land use and land cover changes recorded on archival maps and pictures and with population changes in the study area it was found that the two successive trends of catchment settlement and later depopulation have led to the development of inset terraces on the outlet fans of the skor ansk and hartisov streams in the study catchments both settlement deforestation and depopulation land abandonment occurred very rapidly which also caused abrupt geomorphic changes before human disturbance fluvial erosion and the redeposition of older pleistocene deposits predominated as a result coarse gravel alluvia were deposited within stream channels the stage of massive overbank accumulation of fine grained alluvia was a reflection of intensified delivery of slope material into valley floors from catchments deforested by the wallachians the later stage of vertical incision of channels resulted from the decrease of sediment supply from hillslopes to river channels during catchment depopulation and afforestation

geomagnetic and mineral magnetic characterization of the anthropocene geomagnetic and mineral magnetic data provide geological indices that are both independent of human impact i e geomagnetic and respond to human induced environmental impact i e mineral magnetic we provide the first discussion of such magnetic events for help in defining the anthropocene within the holocene a potential geomagnetic marker for the anthropocene is the low dipole latitude at c 2700 cal a bp which is associated with distinct palaeosecular variation features in northerly mid to high latitude sites mineral magnetic records from lake and marine sediments identify major deforestation and soil delivery events from catchment systems in many parts of the world during the last 4000 years in europe clusters of these events occur around both 2600 cal a bp and ad 1100 the former coinciding with a low in geomagnetic field dipole latitude and peak intensity mineral magnetic records in peats and lake sediments can reflect particulate pollution from fossil fuel burning the expansion of major coal burning began c ad 1800 in western europe and eastern north america but around ad 1900 this expanded due to more widely distributed coal use and this event is the most clear mineral magnetic marker for the base of the anthropocene

the geology and geophysics of kuiper belt object 486958 arrokoth the cold classical kuiper belt a class of small bodies in undisturbed orbits beyond neptune is composed of primitive objects preserving information about solar system formation in january 2019 the new horizons spacecraft flew past one of these objects the 36 kilometer long contact binary 486958 arrokoth provisional designation 2014 mu69 images from the flyby show that arrokoth has no detectable rings and no satellites larger than 180 meters in diameter within a radius of 8000 kilometers arrokoth has a lightly cratered smooth surface with complex geological features unlike those on previously visited solar system bodies the density of impact craters indicates the surface dates from the formation of the solar system the two lobes of the contact binary have closely aligned poles and equators constraining their accretion mechanism

response of fluvial aeolian and lacustrine systems to late pleistocene to holocene climate change lower moravian basin czech republic abstract late pleistocene to holocene morava river valley fill of the eastern czech republic reflects the geomorphic evolution of the valley as forced by climate change valley fill stratigraphy was studied through measured sections optically stimulated luminescence osl and radiocarbon dating ground penetrating radar surveys of relict sand dunes archived drill hole data and a comparison of elevations and ages of stratigraphic units fluvial systems evolved from meandering with floodplains to braided during mis 3 braided fluvio aeolian systems dominated through mis 2 and the last glacial maximum lgm valley aggradation occurred during arid glacial times of a low water to sediment discharge ratio most valley fill was removed at 13 ka with incision by a large bend meandering river with an estimated bankful paleodischarge 3 larger than the modern morava river the holocene morava river has varied from meandering to anabranching with low rates of floodplain aggradation the bzenec sand body up to 36 m thick represents an erosional remnant bypassed during late pleistocene incision and consists of interpreted lacustrine turbidites overlain by braided stream and aeolian dune strata the turbidites consist of laterally continuous thin normally graded beds of rounded and frosted sand grains of aeolian origin dates and elevation data argue that the valley lake formed during the lgm through downstream damming by a braided terminal fan and sand dune complex the turbidites are interpreted to have formed through fluvial undercutting and slumping of dune accumulations as lake level rose this process forced an erosional unroofing of aeolian accumulations reflected in inverted osl dates for the turbidites

geochemical background in polluted river sediments how to separate the effects of sediment provenance and grain size with statistical rigour abstract defining anomalies from geochemical background is a principal step in anthropogenic contamination studies and environmental risk assessment and yet the complexity of processes affecting the composition of sediments makes this task extremely difficult we address grain size and sediment provenance as two parameters influencing the geochemistry of contaminated fluvial sediments we analysed 576 sediment samples from channels floodplains oxbow lakes and dam reservoirs of the morava river czech republic the geochemical data are compared with grain size and statistically processed using primary observations and log ratios an effective way to remove the grain size and provenance effect is to use enrichment factors calculated from least trimmed squares regression of pb zn cu and cr data vs normalizing ti which is sensitive to grain size based on empirical testing titanium proved more suitable for normalizing than did al and rb isometric log ratio coordinates of the pb zn cu and cr data show a strong misfit with those defined by the enrichment factors a log ratio approach considering just subcompositions of elements with similar geochemical behaviour provides much better results

evidence for mediaeval soil erosion in the south hams region of devon uk a major theme of research into the causes of past and present soil erosion has been to determine the relative importance of climate and land use change in influencing holocene erosion rates previous work suggests that land use change especially the conversion of woodlands into agricultural land is the main factor influencing long term increases in soil erosion a study of an extensive minerogenic sediment deposit in a wetland at slapton ley in devon suggests that agricultural intensification occurred before the onset of sedimentation a silty clay layer c 40 cm thick in the valley bottom wetland of the slapton sewage works marsh the base of the silty clay layer lies at an altitude of between 2 2 and 2 6 m aod and has been radiocarbon dated at two locations conventional radiocarbon ages 2 were 910 160 yr and 960 140 yr bp successful radiocarbon dating of the upper surface of this minerogenic layer at one location yielded a conventional radiocarbon age of 730 120 yr bp within the errors

problems of dating alluvium using buried subfossil tree trunks lessons from the black oaks of the vistula valley central europe dating of alluvia of large rivers based on subfossil tree trunks is discussed using examples from the vistula valley near krakow and from literature referring to central europe the method which has been used hitherto for dating alluvia based exclusively on single trunks or single generations has led usually to erroneous results because the majority of trunks in the alluvia were redeposited den drochronology is helpful in solving problems of dating alluvia which should use only in situ trunks i e trunks with bark sapwood and branches equally suitable materials are stumps in growth position which were cut down with an axe and which are preserved by an aggradating river these stumps possess well preserved root systems with roots of a lower order redeposition of trunks in alluvia is associated with lateral migration of a river channel channel migration leads to the washing out of subfossil trunks of different ages from older alluvia these trunks heavier than water are redeposited at the level

the holocene fluvial chronology of spain evidence from a newly compiled radiocarbon database abstract a critical analysis of 74 radiocarbon dates selected from a total of 102 published and unpublished dates from holocene fluvial environments in spain has identified a number of periods of increased fluvial activity in spain namely 11 170 10 230 9630 8785 7980 6860 5800 4800 3880 3085 2895 1820 1300 0 cal bp the latter period reflecting sustained fluvial response to increased human impact the radiocarbon samples were classified according to type of depositional environment a alluvial overbank b flood basin c alluvial channel gravels d fluvio torrential deposits and e slackwater flood deposits palaeofloods dates from slackwater flood deposits indicated at least five phases of increased frequency of large magnitude floods during the holocene 10 855 10 230 9530 8780 2880 2430 975 790 and 520 265 cal yr bp flood basin type deposition occurred from 7980 to 4830 cal yr bp the main clusters of dates from alluvial floodplain deposits occurred at 2750 2150 and 930 520 cal yr bp the record is discussed in relation to other palaeoenvironmental archives including pollen records of holocene vegetation change and palaeoclimatic proxies such as the north atlantic drift ice record comparison with the latter indicates that major holocene flooding coincided with cold climate phases during 9530 9280 2880 2430 and 520 265 cal yr bp a cooling phase at 10 855 10 230 and warming phases at 9030 8780 and 975 790 cal yr bp

late holocene evolution of the becva river floodplain outer western carpathians czech republic abstract to reconstruct the geomorphic imprint of the anthropogenic and natural environmental changes in the late holocene we studied the alluvial record of the becva river floodplain outer western carpathians czech republic coring geophysical sounding and lithological analysis of floodplain deposits supported by ams accelerator mass spectrometry dating enabled the establishment of the primary evolutionary stages of late holocene floodplain evolution during the late atlantic and early subboreal periods gravel aggradation and braided environments occurred in the studied floodplain the late subboreal and early subatlantic are characterised by overbank sedimentation and the middle subatlantic is marked by the recurrence of gravel aggradation a major incision phase took place during the mediaeval warm period the onset of overbank sedimentation in the 15th century correlated with ongoing deforestation of the lower parts of catchment and colonisation of the mountain ridges during the 16th 17th centuries further accelerated this process during the 20th century reforestation of mountains and river channel training resulted in a significant incision phase our data suggest that climate fluctuations were major driving factors for the morpho sedimentary evolution of the floodplain approximately up to the 12th century whereas in the latter evolution period anthropogenic activity superseded natural factors this transition occurred more than one millennium later than in other central and western european catchments

tracing the transport of anthropogenic lead in the atmosphere and in soils using isotopic ratios the isotopic composition of lead in aerosols and soils in israel is used to characterize the sources of anthropogenic lead in the region to ascertain the isotopic composition of natural rock derived lead in specific areas and to determine rates of anthropogenic lead migration in soils the isotopic composition of lead currently emitted from cars in israel 206pb207pb 1 115 2 is controlled by alkyl lead produced in france and germany in addition to petrol lead two more sources of anthropogenic lead can be detected in sampled aerosols the first one has low concentrations of lead 4 ng m3 and 206pb207pb 1 157 and is most likely lead emitted in turkey that traveled across the eastern mediterranean basin the second type of aerosols contains a mixture of lead emitted in several countries including turkey greece and ukraine 206pb207pb value of 1 155 1 160 pb 20 30 ng m3 anthropogenic lead is more accessible for acid leaching than natural lead therefore it is more labile in the soil the isotopic composition of lead in the acid leached fraction of near road soil profiles record the histor of alkyl lead emission in the country based on changes in the isotopic composition of lead with soil depth it is estimated that anthropogenic lead migrates into the soil at approximately 0 5 cm y a soil profile from a relatively remote area is less contaminated by anthropogenic lead and displays a different distribution of lead isotopic values with depth the isotopic composition of lead suggests that natural lead in soils developed on carbonate bedrock is derived from clays either from the rock esidue the clay fraction in the carbonate bedrock or from airborne clay but not from lead released from the carbonate fraction in the rock

long term pedolithogenic rhythms in the holocene abstract soil sedimentary series in subordinate accumulative and trans accumulative landscapes represent the most complete and detailed record of the development of soils topographic forms and local geosystems in the holocene a new conception of centuries long rhythms of soil formation and erosion is offered on the basis of literature analysis and original data on 80 pits within the east european plain supplied with 180 radiocarbon dates it is established that the holocene the last 10 500 years comprises seven stages of soil formation alternating with stages of intensive erosion and sediment accumulation 450 950 2300 2700 4200 4700 6300 6600 7700 8100 9500 10 200 bp the intervals of 450 150 1050 2300 2800 4200 4700 6200 6600 7700 8300 9500 and 10 200 10 400 bp correspond to the formation of soils in the geochemically subordinate footslopes gully bottoms floodplains landscapes the erosion lithogenetic stages are characterized by humid warm and cold and also arid cold climatic conditions the pedogenetic stages in subordinate landscapes of the forest steppe and forest zones fall mainly into arid warm and sometimes humid warm and arid cold climatic phases of the 2000 year long rhythm known as the shnitnikov rhythm

three dimensional field perspective on deformation flow and growth of the lower continental crust dharwar craton india 1 the study of fabric development and juvenile batholith emplacement across the tilted crustal section of the eastern dharwar craton shows that horizontal constrictional deformation affected large volumes of the midcrust and lower crust at the time of regional partial melting and magmatic accretion constriction is achieved by a combination of coeval shallow and steep planar fabrics sharing a common horizontal elongation direction two sets of conjugate strike slip shears and extensional shear zones the eastern dharwar craton illustrates an end member deformation mode by which a particularly weakened lithosphere responds to shortening by developing distributed horizontal plane strain on a crustal scale resulting from the combination of crustal shortening and lateral gravity driven flow thinning accompanying constrictional deformation is interpreted as compensating for juvenile magmatic accretion and thickening of greenstone belts and as acting to maintain a stable crustal thickness such a midcrustal to lower crustal deformation process may provide a resolution of the batholithic room problem in a softened crust submitted to lateral shortening and may explain nearly isobaric retrograde pressure temperature time paths of high temperature low pressure high grade terrains

surprisingly small increase of the sedimentation rate in the floodplain of morava river in the stražnice area czech republic in the last 1300 years abstract sediment profiles from the floodplain of morava river in the czech republic have been collected from exposed river banks 4 6 m long sections and cores 2 4 m deep and investigated using a set of geochemical proxies validated by granulometry and conventional geochemical analysis outlined in our previous paper the work was conducted to evaluate the increase in sedimentation rate during medieval and modern time periods correlation of sediments along the current channel belt allows identification of two most important synchronous changes in the channel structure over the past 1300 years in the 13th century and at the end of the 16th century these changes could be related to central european climatic extremes rather than to land cover land use practises analysis of the pollen record in peaty deposits at the floodplain edge allows excluded dramatic deforestation in medieval times maps of the area from the last five centuries revealed direct and indirect signs of past avulsions and clearly show how the original multichannel system was transformed into a single meandering channel in the early 20th century the extrapolated aggradation rate net vertical accretion of floodplain fines except for levee sediments increased from 0 2 0 3 cm year in 700 ad to 0 3 0 4 cm year in 2000 ad depending on the grain size of the sediment this is the smallest yet reported enhancement of siliclastic deposition although morava river watershed has been intensively used for agriculture and its land cover has changed in a manner similar to west and central european rivers

morava river floodplain development during the last millennium stražnicke pomoravi czech republic floodplain sediments deposited along the lower course of the morava river eastern czech 206 pb 207 pb and pop ddt pcb analysis and 137 cs activity data thecu trienmethodwasusedforstratigraphicallycorrelatingthesedepositsbasedonthevariationofexpand able clay minerals in the sediments the resulting stratigraphic pattern reveals the alluvial history of the cur rently active river channel system since the end of the first millennium ad fine overbank clayey sediments deposited during the mediaeval warm period were eroded from cultivated fields newly formed during mediaeval colonization between 1250 and 1450 these fine deposits are overlain by coarser floodplain sedi mentsofthe littleiceage indicatingachangeinthesedimentsourcesincethesixteenthcentury ad anda substantial increase in the sediment load in the second half of twentieth century the straunicke pomoravi floodplaindepositsrepresentavaluablepalaeoenvironmentalarchiveofthelastmillennium containingrecords offluvialprocessesconsiderablyalteredbyhumanactivities

sensitivity of west and central european river systems to environmental changes during the holocene a review abstract sediment deposition in floodplains is an essential part of the sediment dynamics of a catchment these sediment dynamics can vary largely on a holocene time scale under the influence of driving forces such as land use and climatic variations in this paper we review the holocene floodplain sediment deposition history of rivers in west and central europe with special attention to the influence of climate and land use variability during the early holocene preboreal to atlantic period most floodplains were rather stable with limited floodplain aggradation after this initial phase of relative stability sedimentation rates increase during the middle and late holocene with often the most important deposition phase during the last 1000 to 2000 a the start of the increase in sedimentation varies spatially with an earlier start in the west france germany then in the east poland belarus ukraine while there are also local differences between regions which are settled early e g loess regions compared to later settled regions the sedimentation history of most floodplains can be linked to the local land use history while influence of climatic variations on floodplain aggradation is often reported to be of minor importance processes related to bedload are often reported to be more influenced by climatic events relationships between the driving forces and the sediment history are mainly based on synchronicity and there is seldom proof for a direct causal relationship future research should focus on a system based approach integrating the floodplain deposition in the entire sediment dynamics which includes also erosion colluvial deposition and export main research questions that need further attention include integration of system based concepts like landscape connectivity and buffering effects and also the assessment of the individual contribution of land use changes and climatologic variations on the sediment dynamics detailed sediment budget studies combined with modeling studies can make an important contribution to the understanding of floodplain sediment dynamics

grain size of the overbank deposits as carriers of paleogeographical information abstract overbank deposits of the vistula river and its tributaries were deposited during the whole late glacial and the holocene but at various rates they are differentiated with respect to the grain composition that corresponds to climatic vegetation changes at the turn of the late glacial and the holocene to anthropogenic deforestation in the neoholocene and to the distance from an active channel

quantification and regulation of organic and mineral sedimentation in a late holocene floodplain as a result of climatic and human impacts taligny marsh parisian basin france quantification in grams per metres squared per year of the sediment accumulation in a flood plain marsh located in the southwestern parisian basin showed that there is no close relationship between the accumulation of organic matter om and mineral matter mm during the late holocene and provided an accurate view of the distinct yield and storage conditions of both sediment components endogenic om accumulation in peaty sediments is not related to the climate but to felling of the alder forest and its substitution by cyperaceae and paludal taxa in the marsh iron age and middle ages mm accumulation expresses mainly the sediment yield on the slopes determined by landuse during an initial phase from the late neolithic to the early middle ages land use change from crop cultivation to pastureland possibly related to climate deterioration led to a decrease in the sediment yield during a second phase since the early middle ages the considerable development of crop cultivation over pasturing even during periods of climate deterioration such as the little ice age led to a sharp increase in sediment yield however although sediment yield was high the hydrodynamics in the fen did not favour particle retention thus since the neolithic yield and storage of om and mm sediment have been marked by human activities initially with high climatic stress but since the middle ages without significant climatic stress

geochemical tools for the stratigraphic correlation of floodplain deposits of the morava river in stražnicke pomoravi czech republic from the last millennium article i nfo the floodplain of the morava river in stra nicke pomoravi south east moravia czech republic contains a very valuable record of regional environmental change which goes back to several thousand years its interpretation has been limited by poor stratigraphic correlation and dating of the sediments we present a geochemical solution to this challenge we studied 8 outcrops of floodplain deposits from 4 localities along a 6 km long part of the current meander belt of the morava river in stra nicke pomoravi using geochemical proxy analyses magnetic susceptibility measurements 14 c dating of wood remnants and sediment micromorphology the proxy methods are based on elemental analysis edxrf and analysis of the cation exchange capacity of clay minerals granulometric analyses provided the basis for lithological and facies assignment of the sediments our geochemical and mineralogical interpretations have further been tested by microstratigraphically studying the optical properties of the fine fraction horizons older than about 3 centuries were 14

interpreting alluvial archives sedimentological factors in the british holocene fluvial record abstract a holocene alluvial archive of 506 dated units for great britain is analysed in terms of the sedimentation styles involved the database is classified by sedimentation unit channel sediments palaeochannel fills floodplain surface sediments floodbasins and colluvial deposits and alluvial ensemble fans and cones upland gullies and streams braided systems and active inactive meandering and anastomosing systems floodplain palaeochannel and floodbasin sediments dominate the record mostly from meandering anastomosing systems different sediment units show varied potential for recording environmental change some are relatively poorly dated with respect to the volumes of material involved whilst many dates float in periods of depositional activity which lasted for extended time periods much dated activity is autogenic and of relatively little value in interpreting external environmental influence ensembles and units are similar in age patterns in some respects commonly they exhibit sets of short term peaks in sedimentation activity but differ in others floodbasins and to an extent braided systems feature in the earlier holocene whilst dated fan deposition is more evident in the late holocene there is a general bias towards sediment units of late holocene age which probably reflects preservation factors previous british holocene alluviation models are reviewed it is suggested that the majority of earlier models reflect partial views imposed by limited regional coverage and available dating

change in the frequency of extreme events as the indicator of climatic change in the holocene in fluvial systems abstract the transformation of natural systems of climatic origin in the holocene may be realised by a change in the type of extreme events or by a change in their frequency or by both the rapid warming at the younger dryas preboreal transition exemplifies a parallel drop in frequency and a change in the type of events several wetter phases of the holocene are characterised by rises in frequency of various types of extreme rainfalls the fragmentary records of events in the fluvial and slope systems coincide with smoothed variations in stable ecosystems and shifts of ecotonal zones such as tree line and lake levels

use of floodplain sediment cores to investigate recent historical changes in overbank sedimentation rates and sediment sources in the catchment of the river ouse yorkshire uk abstract floodplain sediment cores collected from seven sites in the catchment of the river ouse in yorkshire uk have been used to provide information on recent historical changes in both rates of overbank sedimentation and sediment sources the environmental radionuclides 137 cs and unsupported 210 pb have been used to establish chronologies for each core and to estimate average sediment accumulation rates for the last ca 30 and 100 years respectively average sedimentation rates for the individual cores ranged from 0 11 to 1 04 g cm 2 yr 1 in all but one case the estimates of average sedimentation rate during the last ca 30 years for the individual cores are broadly similar to those for the last ca 100 years suggesting that overbank sedimentation rates have been essentially uniform over the longer time period composite fingerprints based on a combination of geochemical and mineral magnetic properties and a numerical mixing model have been used to investigate downcore changes in sediment source in the case of source type most of the cores reflect a primarily topsoil source although there have been periods with increased contributions from subsoil channel bank sources within the ouse basin in general the period commencing in the late 19th and early 20th century and extending through to the 1960s was characterised by increased contributions from topsoil sources however contributions from subsoil channel bank sources have increased over the last few decades the source tracing results relating to sediment contributions from the three main geological topographic zones are in broad agreement with the proportion of the area of the catchment underlain by each rock type temporal variations in the contributions from the three geological topographic zones vary from site to site but for the lower reaches of the river ouse contributions from areas underlain by permian and triassic rocks which mainly outcrop in the vale of york have increased since the turn of the century the changes in sediment source identified are probably a reflection of changes in land use and management and possibly changes in climate these results enable estimates of contemporary suspended sediment fluxes and sources to be placed into a historical context and provide a means of considering the likely impact of potential future changes in land use and climate in the study basin

a rapid method for magnetic granulometry with applications to environmental studies we have developed a rapid method of characterizing the fine scale variation sub micron to hundreds of microns m in the grain size of magnetite in long sediment cores this method is a new rock magnetic tool and can be readily applied to the following disciplines 1 environmental studies 2 hydrology 3 petrology and 4 geomagnetism the method consists of a comparative plot of the depth variation of two magnetic parameters the first parameter low field less than 0 1 millitesla mt or 1 oe susceptibility in a steady field is plotted on the abscissa the second parameter anhysteretic remanent magnetization arm imparted by a smoothly decreasing af of peak value 100 mt 1 000 oe in the presence of a weak steady field 0 01 0 1 mt or 0 1 1 oe is plotted on the ordinate for a sediment column in which the magnetic mineral is magnetite a plot of the two magnetic parameters shows transitions in the average magnetic grain size with depth as clearly discernible changes in the slope of a regression line fit to the individual points arm

sediment accumulation rates and high resolution stratigraphy of recent fluvial suspension deposits in various fluvial settings morava river catchment area czech republic abstract we present a comprehensive study concerning sedimentary processes in fluvial sediment traps within the morava river catchment area czech republic involving three dammed reservoirs four meanders and oxbow lakes and several natural floodplain sites the objective of the study was to determine sediment accumulation rates sar estimate erosion rates calculating these using a combination of the 137 cs method and historical data another purpose of this study was to provide insight into changing erosion and accumulation rates over the last century extensive water course modifications were carried out in the morava river catchment area during the twentieth century which likely affected sedimentation rates along the river course other multiproxy stratigraphic methods x ray densitometry magnetic susceptibility and visible light reflectance spectrometry were applied to obtain additional information about sediment infill sediment stratigraphy revealed distinct distal to proximal patterns especially in reservoirs granulometrically silts and sandy silts prevailed in sediments oxbow lakes and meanders contained larger amounts of clay and organic matter which is the main difference between them and reservoirs pronounced 137 cs peaks were recorded in all studied cores maximum 377 bq kg 1 thus indicating chernobyl fallout from 1986 or older events calculated sediment accumulation rates were lowest in distal parts of reservoirs 0 13 0 58 cm y and floodplains 0 45 0 88 cm y moderately high rates were found in proximal parts of reservoirs and oxbow lakes 2 27 4 4 cm y and the highest rates in some oxbow lakes located near the river 6 8 cm y the frequency of the inundation still can be high in some natural areas as in the litovelske pomoravi protected area whereas the decreasing frequency of the inundation in other modified parts can contribute to a lower sedimentation rate the local effects such as difference between sars in oxbow lakes and reservoirs different grain size distribution in both systems and high variability in thickness of their proximal and distal parts play a crucial role in the analysis of regional accumulation rates local effects are much stronger than regional effects such as rainfall and land use combined with the low resolution of time scales usually only three datums are available reservoir construction datum 137 cs fallout event and top of sediment these effects may obscure the general trends of regionally increasing or decreasing net sars making the analysis of erosion rates from the sedimentary record an extremely difficult task

geochemical normalization of magnetic susceptibility for investigation of floodplain sediments magnetic susceptibility ms is commonly used as a proxy for industrial pollution in natural sediments or as a proxy for the percentage of detrital components in peat or carbonates the ms may also reflect the geology of the sediment source and post depositional processes in sediments such as soil development the aim of our research was to test the usefulness of fe normalized mass specific ms and ti normalized fe in a study of floodplain sediments we sampled 27 floodplain sediment cores from several geologically different catchments throughout the czech republic analysed their fe and ti concentrations using x ray fluorescence spectroscopy and determined their to decipher sediment grain size dependence and possible magnetic enrichment background functions for were constructed using similar approach as that used for geochemical background functions of the risk element concentrations with fe concentrations as an independent variable it provides a mechanism to calculate of sediments as it would be pristine i e without post depositional changes and pollution sediments derived from mafic source rocks had fe larger by two orders of magnitude than sediments derived from felsic rocks sediments derived from mafic source rocks also exhibit lower mean fe ti ratio in pristine sediment strata than the average upper continental crust the magnetic carriers inherited from mafic rocks are stepwise destroyed by pedogenesis in the floodplains and thus slowly approach of sediments derived from felsic rocks gleying processes may change fe fe ti ratio allows identifying a past action of those post depositional processes

lake baikal climatic record between 310 and 50 ky bp interplay between diatoms watershed weathering and orbital forcing theenvironmentalrecordfromlakebaikal russia from310to50kybp mis9atomis3 wasinterpretedusingrockmagnetic uv vis spectral mineralogical and diatom analyses the age model was based on a correlation of the diatom and chemical weathering records and the summer insolation curve at 55 n and checked against an age model based on the proxy of relative palaeointensity of the earth s magnetic field peaks in chemical weathering within the watershed inferred from maximum concentration of magnetic and coloured minerals and mica the lowest mean fe oxidation state in silicates and highs in expandable clay minerals correlated with the northern hemisphere summer insolation minima at 55 n reconstructed changes in weathering intensity are better correlated to insolation patterns than to global ice volume records we propose a scheme of yet missing palaeoenvironmental interpretation of the diatom assemblage including also some extinct species aulacoseira baicalensis and aulacoseira skvortzowii were abundant in the early stages of lake flora recovery immediately after deglaciation and during mis 7e and mis 5e periods of more pronounced continental climate and peak chemical weathering stephanodiscus formosus var minor cyclotella minuta and cyclotella ornata dominated in intervals of decreased seasonality and decreased humidity at the end of most interglacial interstadial diatom zones stephanodiscus grandis stephanodiscus carconeiformis and stephanodiscus formosus were ubiquitous between mis 8 and mis 5 an interval marked by high seasonality i e large differences between winter and summer insolation and low humidity revealed by a low hydrolysis of expandable clay minerals in the watershed diatom concentrations peaked in the climatic optima of mis 7e and mis 5e and in the short periods marked by shifts to warmer conditions in the upper sections of mis 5 mis 5c 103 99 ky bp mis 5b 90 88 ky bp and mis 5a 84 79 ky bp in which increased humidity resulted in enhanced hydrolysis of clay minerals no such short similar climatic optimums were found from mis 9a to mis 6 sharp climate deteriorations recorded in the diatom and clay mineral records at 107 94 and 87 ky bp however occurred within 1 2 ky of cold extremes in north atlantic sea surface temperature emphasizing the strong teleconnections between the two localities 2007 elsevier b v all rights reserved

past hydrological events reflected in the holocene fluvial record of europe abstract a comprehensive database of radiocarbon dated fluvial units in great britain poland and spain has been compiled to investigate the relationship between environmental change flooding and holocene river dynamics following the methodology recently developed by macklin and lewin macklin m g lewin j 2003 river sediments great floods and centennial scale holocene climate change journal of quaternary science 18 101 105 radiocarbon dates in fluvial sequences that coincide with a modification in sedimentation rate or style have been highlighted allowing geomorphologically significant changes in holocene river activity to be identified data analysis has been undertaken at both national and sub national scales and on catchments of different size type and land use history multiple phases of higher flood frequency characterized by accelerated erosion and sediment deposition on floodplains are recognized and compared with a range of climate proxies the relative and varying roles of climate and land use on river dynamics are considered and the value of the database for reconstructing past hydrological events as well as for predicting river response to future environmental change is assessed

land use change soil erosion and alluvial dynamic in the lower doubs valley over the 1st millenium ad neublans jura france abstract geochemical and particle size analyses surface scanning magnetic susceptibility microscopic charcoal counting and pollen analysis have been carried out on two cores from the lower doubs valley in order to reconstruct the land use history the interpretation of anthropogenic pollen indicators and micro charcoal deposits is discussed in relation to the lithological variation of sedimentary accumulation and evolution of the settlement the environmental changes which occurred during the 1st and the 6th century ad reflect the impact of human activities on the landscape in the immediate surroundings of the site multiproxy indicators indicate that soil erosion as a consequence of agricultural activities including fire practices a reactivation of hydrologic flow of the river recorded in the sedimentary sequences attests to a larger environmental perturbation between 1st 3rd and 7th 8th century ad

human induced prehistoric soil buried in the flood plain of svratka river czech republic the natural setting and prehistoric human activity on holocene floodplains in central europe is a compelling issue from several points of view this environment presents an important sedimentary ar

environmental magnetism as a dating proxy for recent overbank sediments of peri industrial regions in the czech republic and uk abstract twenty five floodplain sediment profiles from seven rivers in eastern czech republic and three in north west england were collected to examine the hypothesis that magnetic enhancement in recent sediments is predominantly of anthropogenic origin and that magnetic parameters can be used as a dating proxy reflecting changes in intensity of industry sources over time natural sources of magnetic enhancement were excluded and anthropogenic enhancement was identified as exhibiting elevated values of lf arm sirm sirm and s ratios with low values of fd magnetic spherules typically formed through fossil fuel combustion processes were observed by scanning electron microscopy sem in these sediments to assess the potential of magnetic parameters as a chronometer the approach was compared with frequently used dating techniques concentrations of heavy metals and 137 cs the floodplain profiles were divided to three groups according to the characteristics of their trends with depth in magnetic parameters lf in particular and the suitability of magnetic properties as a dating proxy group 1 which included the majority of the profiles exhibited magnetic enhancement in the upper part of its profiles and a single maximum in lf this group exhibited a clear suitability for our proposed magnetic dating as the magnetic record reflected the industrial history of the region and was aligned with the chronologies of the other dating techniques profiles magnetically enhanced throughout their depth and lacking any clear trend comprised group 2 here a mineral magnetic approach to dating was limited as the magnetic signal was diluted by a high sedimentation rate or impacted by local anthropogenic factors all profiles from england were included in group 3 because their magnetic depth profiles were influenced by natural sources of magnetic particles or specific sedimentary conditions and a longer industrial history and thus needed an individual interpretation however they still reflected the regional deposition history of industrial sources of ferrimagnetic particles overall magnetic parameters proved to be an efficient dating proxy with potential for recently aggrading rivers

past hydrological events reflected in holocene history of polish rivers abstract a database of 335 radiocarbon dates from holocene fluvial sediments in poland has been compiled each sample is characterized by 25 parameters all samples were grouped into one of 7 regions characterized by hydrological regime and one of 8 depositional environments statistical analysis was used to enhance the palaeoenvironmental data and 17 phases may be distinguished 10 of which have a distinct sharp peak abandoned paleochannels 149 dates clearly reflect the major wetter phases of the holocene an opposite picture is presented by overbank aggradation 86 dates connected mainly with expansion of agriculture preliminary correlations are made on peat bog records changes in vegetation lake water level rates calcareous tufa and speleothems growth landslides phases and debris flow phases these show many convergences explained by climatic fluctuations during the holocene

electrical resistivity imaging of anastomosing river subsurface stratigraphy and possible controls of fluvial style change in a graben like basin czech republic abstract subject to frequent channel avulsions due to the increased frequency of floods rise of base level and or sediment overloading anastomosing rivers are sensitive to external climatic or tectonic forcing in sedimentary basins the morava river czech republic shows a well developed holocene anastomosis confined to the pull apart type upper morava basin umb we studied the stratigraphy and aggradation rates of the umb using electrical resistivity tomography ert dipole electromagnetic profiling demp core data and radiocarbon ages with the aim of identifying factors triggering the anastomosis at the pleistocene holocene transition the ert and demp proved to be excellent tools to visualize the shape and thickness of floodplain depositional units abandoned meanders scroll bars etc the major geophysical surfaces identified are the base of the late weichselian braided stream deposits osl age 34 53 3 42 ka interpreted as a palaeo stream gradient of the morava river and their transition to holocene floodplain deposits in the late weichselian the river aggraded at an average rate of 0 2 mm yr the holocene oldest 14c age 7 066 0 072 ka short term aggradation rates reached up to 13 7 mm yr but the average long term rates 0 07 to 0 4 mm yr are comparable to the late weichselian the stratigraphy and sediment ages indicate that the onset of anastomosis was not likely associated with accelerated basin subsidence possible controls of the anastomosis include upstream control by numerous tributaries large wood debris in the floodplain forests and changes in land use the tectonic and geomorphic context of the umb pull apart basin probably favoured the development of the anastomosis