formal definition and dating of the gssp global stratotype section and point for the base of the holocene using the greenland ngrip ice core and selected auxiliary records the greenland ice core from northgrip ngrip contains a proxy climate record across the pleistocene holocene boundary of unprecedented clarity and resolution analysis of an array of physical and chemical parameters within the ice enables the base of the holocene as reflected in the first signs of climatic warming at the end of the younger dryas greenland stadial 1 cold phase to be located with a high degree of precision this climatic event is most clearly reflected in an abrupt shift in deuterium excess values accompanied by more gradual changes in d 18 o dust concentration a range of chemical species and annual layer thickness a timescale based on multi parameter annual layer counting provides an age of 11 700 calendar yr b2 k before ad 2000 for the base of the holocene with a maximum counting error of 99 yr a proposal that an archived core from this unique sequence should constitute the global stratotype section and point gssp for the base of the holocene series epoch quaternary system period has been ratified by the international union of geological sciences five auxiliary stratotypes for the pleistocene holocene boundary have also been recognised copyright 2008 john wiley sons ltd

high resolution fluvial records of holocene environmental changes in the sahel the yame river at ounjougou mali west africa abstract the yame river in the bandiagara plateau dogon country mali is characterised by extensive alluvial sedimentary records particularly in the 1 km long ounjougou reach where holocene floodplain pockets are inset in the pleistocene formations these alluvial records have been investigated via geomorphologic fieldwork and sedimentologic and micromorphologic analyses and are supported by 79 radiocarbon dates the alluvial deposits of the valley floor correspond to a vertical accretion of 3 10 m the reconstruction of fluvial style changes provides evidence of four main aggradation periods from 11 500 to 8760 cal bp the alluvial architecture and grain size parameters indicate a wandering river this period included phases of pulsed high energy floods and avulsion related to a northward shift of the summer monsoon to around 14 n after 11 500 cal bp from 7800 to 5300 cal bp a swampy floodplain environment with standing water pools within a sudanian savanna woodland mosaic corresponds to the culmination of the holocene humid period from 3800 cal bp onwards rhythmic sedimentation attests to an increase in the duration and or intensity of the dry season giving a precise date for the local termination of the holocene optimum period during the last two millennia and for the first time during the holocene the alluvial formations are progressively restricted whereas the colluvial deposits increase indicating strong soil erosion and redeposition within the watershed related to an increase in human impact four major periods are characterised by incision i1 ante 11 500 i2 8760 7800 i3 6790 6500 cal bp i4 2400 1700 cal bp pointing to dramatic changes in fluvial style they result from high energy flood flows during dry spells and confirm the capacity of the floodplain pocket in the upstream reach of the sahelian belt to record rapid holocene climatic change

river network evolution and fluvial process responses to human activity in a hyper arid environment case of the tarim river in northwest china abstract the tarim river the longest dryland river in an extremely arid region of china has undergone ever increasing human impacts over recent centuries particularly since the late 1950s during which time large scale land reclamation in the basin has taken place historical literature maps gauged hydrological data and satellite images were analyzed to examine how the river network evolution in the basin and the fluvial morphology of the main stem of the tarim river have responded to human influences the results demonstrate that human activity inhabitation land reclamation and water resources development in the basin have had significant impacts on the tarim river causing major changes in runoff and sediment transport river network composition and river morphology especially planform patterns gauged hydrological data from the past five decades presented an obvious reduction in runoff and sediment load in the tarim river even though the runoff from source tributaries exhibited a gentle increase the annual occurrence of low flow events showed a significant increase and the occurrence of moderate high flow events followed a gentle decrease the river network system has disintegrated from a historically quasi centripetal system with nine tributaries into several isolated river systems which have mainly developed since the 20th century currently only four tributaries flow into the main stem river which is dominated by braided channel patterns in the upper reaches and meandering typically with distorted bends patterns in the middle reaches the braided reach was in aggradation and in high lateral mobility the mean width and braiding intensity of the braided reach followed a gentle decrease mainly due to the reclamation of river flood plains to farmlands and embankments the sinuosity index of the current tarim river channel is distinctively lower than the indexes of the old channels that were abandoned decades or centuries ago even though the sinuosity index of the meandering channel followed a gentle increase in recent decades due to the increased occurrence of low flow events human activity has changed the natural fluvial processes and morphology of the tarim river and has reduced the diversity of the river network system

the bisagno stream catchment genoa italy and its major floods geomorphic and land use variations in the last three centuries abstract the city of genoa liguria italy and the bisagno valley are affected by frequent floods often with loss of human lives historically characterised by high flood hazards the bisagno valley was recently affected by a flood event on 9 october 2014 less than three years after the tragic flood event of 4 november 2011 when six people died including two children in the last 50 years four destructive floods occurred in the bisagno valley in addition to some other events that caused significant damage and economic losses this paper examines the three largest flood events in terms of intensity and ground effects which affected the bisagno valley in the last three centuries the flood of 25 october 1822 well documented by contemporary sources the flood of 8 october 1970 undoubtedly the most tragic on record and the very recent event of 9 october 2014 for this purpose scientific and historical geographical methodologies were adopted the latter particularly useful for the reconstruction of the flood event of 1822 and the landscape history of the bisagno valley in the nineteenth century this comparison shows that the bisagno valley is characterised by climatic and landform features that have been making the flood events historically common in the area however recent climate change and land use variations including some major modifications of the catchment basin have progressively determined a decrease of the concentration time and an increase of runoff solid transport and flood hazard consequently in recent decades a growth in the number of flood events occurred to the extent that the bisagno today is a famous case study on an international scale

a model of channel response in disturbed alluvial channels dredging and straightening of alluvial channels between 1959 and 1978 in west tennessee caused a series of morphologic changes along modified reaches and tributary streams degradation occurred for 10 to 15 years at sites upstream of the area of maximum disturbance and lowered bed levels by as much as 6 1 m following degradation reaches upstream of the area of maximum disturbance experienced a secondary aggradation phase in response to excessive incision and gradient reduction aggradation downstream of the area of maximum disturbance reached 0 12 m per year with the greatest rates occurring near the stream mouths the adjustment of channel geometry and phases of channel evolution are characterized by six process oriented stages of morphologic development premodified constructed degradation threshold aggradation and restabilization down cutting and toe removal during the degradation stage causes bank failure by mass wasting when the critical height and angle of the bank material is exceeded threshold stage channel widening continues through the aggradation stage as the slough line develops as an initial site of lower bank stability the bank profile develops three dynamic elements 1 vertical face 70 to 90 2 upper bank 25 to 50 and 3 slough line 20 to 25 alternate channel bars form during the restabilization stage and represent incipient meandering of the channel

catchment reconstruction erosional stability at millennial time scales using landscape evolution models abstract an important part of planning for the rehabilitation of a mine site is the design of stable final landforms for waste rock dumps or spoil piles whilst able to be assessed over the short term years to decades the longer term behaviour centuries to millennia of such landscapes is not within any meaningful human time frame of observation predictive numerical models therefore form an important tool with which current landscape behaviour and longer term trajectory can be assessed however an important issue associated with the use of models is the ability to assess the reliability and accuracy of the model here the siberia and caesar lisflood landscape evolution models lems are used to simulate and assess the geomorphic stability of a conceptual rehabilitated landform of the ranger uranium mine in the northern territory australia for a simulated period of up to 1000 years utilising both models in this study enabled an independent assessment of likely landscape processes and evolution as well as each model results show that siberia and caesar lisflood produce erosion rates and patterns that are broadly similar at millennial time scales short term processes such as gullying appear to be the dominant erosion features in the proposed landforms and may produce substantial erosion in terms of size and amount of hillslope material eroded and transported downslope vegetation was found to have a major effect on the erosion potential of the landform surface overall both models produce very similar results

stratigraphy of the anthropocene the anthropocene an informal term used to signal the impact of collective human activity on biological physical and chemical processes on the earth system is assessed using stratigraphic criteria it is complex in time space and process and may be considered in terms of the scale relative timing duration and novelty of its various phenomena the lithostratigraphic signal includes both direct components such as urban constructions and man made deposits and indirect ones such as sediment flux changes already widespread these are producing a significant event layer locally with considerable long term preservation potential chemostratigraphic signals include new organic compounds but are likely to be dominated by the effects of co2 release particularly via acidification in the marine realm and man made radionuclides the sequence stratigraphic signal is negligible to date but may become geologically significant over centennial millennial time scales the rapidly growing biostratigraphic signal includes geologically novel aspects the scale of globally transferred species and geologically will have permanent effects

downstream hydrologic and geomorphic effects of large dams on american rivers abstract the hydrology and geomorphology of large rivers in america reflect the pervasive influence of an extensive water control infrastructure including more than 75 000 dams one hundred thirty seven of the very large dams each storing 1 2 km 3 10 6 acre feet of water or more alter the flows of every large river in the country the hydrologic effects of these very large dams emerge from an analysis of the stream gage records of 72 river reaches organized into 36 pairs one member of each pair is an unregulated reach above a dam whereas the other is a regulated reach downstream from the same structure comparison of the regulated and unregulated reaches shows that very large dams on average reduce annual peak discharges 67 in some individual cases up to 90 decrease the ratio of annual maximum mean flow 60 decrease the range of daily discharges 64 increase the number of reversals in discharge by 34 and reduce the daily rates of ramping as much as 60 dams alter the timing of high and low flows and change the timing of the yearly maximum and minimum flows in some cases by as much as half a year regional variation in rivers dams and responses are substantial rivers in the great plains and ozark ouachita regions have annual maximum mean flow ratios that are 7 times greater than ratios for rivers in the pacific northwest at the same time the ratio of storage capacity mean annual water yield for dams is greatest for interior western ozark ouachita and great plains rivers and least for pacific northwest streams thus in many cases those rivers with the highest annual variability have the greatest potential impact from dams because structures can exert substantial control over downstream hydrology the hydrologic changes by dams have fostered dramatic geomorphic differences between regulated and unregulated reaches when compared to similar unregulated reaches regulated reaches have 32 larger low flow channels 50 smaller high flow channels 79 less active flood plain area and 3 6 times more inactive flood plain area dams also affect the area of active areas the functional surfaces that are functionally connected to the present regime of the river regulated reaches have active areas that are 72 smaller than the active areas of similar unregulated reaches the geomorphic complexity number of separate functional surfaces per unit of channel length is 37 less in regulated reaches reductions in the size of hydrologically active functional surfaces are greatest in rivers in the great plains and least in eastern streams the largest differences in geomorphic complexity are in interior western rivers the shrunken simplified geomorphology of regulated large rivers has had direct effects on riparian ecology producing spatially smaller less diverse riparian ecosystems compared to the larger more complex ecosystems along unregulated reaches of rivers

paleoenvironmental and paleoclimatic interpretation of the stratigraphic sequence of lezetxiki ii cave basque country iberian peninsula inferred from small vertebrate assemblages naroa garcia ibaibarriaga aitziber suarez bilbao salvador bailon alvaro arrizabalaga maria jose iriarte chiapusso lee arnold martina demuro and xabier murelaga

glacier recession and water resources in peru s cordillera blanca the tropical glaciers of the cordillera blanca peru are rapidly retreating resulting in complex impacts on the hydrology of the upper rio santa watershed the effect of this retreat on water resources is evaluated by analyzing historical and recent time series of daily discharge at nine measurement points using the mann kendall nonparametric statistical test the significance of trends in three hydrograph parameters was studied results are interpreted using synthetic time series generated from a hydrologic model that calculates hydrographs based on glacier retreat sequences the results suggest that seven of the nine study watersheds have probably crossed a critical transition point and now exhibit decreasing dry season discharge our results suggest also that once the glaciers completely melt annual discharge will be lower than present by 2 30 depending on the watershed the retreat influence on discharge will be more pronounced during the dry season than at other periods of the year at la balsa which measures discharge from the upper rio santa the glacier retreat could lead to a decrease in dry season average discharge of 30

annual rainfall and nitrogen isotope correlation in macropod collagen application as a palaeoprecipitation indicator abstract collagen has been extracted and analysed for 15 n from modern kangaroos macropods macropus eugenii m antilopinus m fuliginosus m rufus m robustus in western australia and south australia comparison of nitrogen isotope ratios with annual rainfall for the respective areas produced a good negative correlation for macropods but not for other marsupials this may be related to metabolic adaptations in macropods to compete against water loss hence the correlation between 15 n and annual rainfall may be species specific nitrogen isotope analyses on collagenic material extracted from fossil macropods macropus spp have been determined from two late pleistocene deposits in south australia corroboration with spore pollen and sedimentological data confirm that 15 n of collagenic material can be used as a proxy for palaeoprecipitation levels in australia this has great potential for understanding palaeoclimatic changes especially drought periods in australia during the pleistocene

humans as geologic agents a deep time perspective humans move increasingly large amounts of rock and sediment during various construction activities and mean rates of cropland soil loss may exceed rates of formation by up to an order of magnitude but appreciating the actual importance of humans as agents of global erosion necessitates knowledge of prehistoric denudation rates imposed on land surfaces solely by natural processes amounts of weathering debris that compose continental and oceanic sedimentary rocks provide one such source of information and indicate that mean denudation over the past half billion years of earth history has lowered continental surfaces by a few tens of meters per million years in comparison construction and agricultural activities currently result in the transport of enough sediment and rock to lower all ice free continental surfaces by a few hundred meters per million years humans are now an order of magnitude more important at moving sediment than the sum of all other natural processes operating on the surface of the planet relationships between temporal trends in land use and global population indicate that humans became the prime agents of erosion sometime during the latter part of the first millennium a d

hydrogeomorphological differentiation between floodplains and terraces floodplains and terraces in river valleys play important roles in the transport dynamics of water and sediment while flat areas in river valleys can be identified from lidar data directly characterizing them as either floodplain or terraces isnot yet possible to address this challenge we hypothesize that since geomorphic features are strongly coupled to hydrologic and hydraulic dynamics and their associated variability there exists a return frequency or possibly a narrow band of return frequencies of flow that are associated with floodplain formation and this association can provide a distinctive signature for distinguishing them from terraces based on this hypothesis we develop a novel approach for distinguishing between floodplains and terraces that involves transforming the transverse cross sectional geometry of a river valley into a curve named river valley hypsometric rvh curve and linking hydraulic inundation frequency with the features of this curve our approach establishes that the demarcation between floodplains and terraces can be established from the structure of steps and risers in the rvh curves which can be obtained from the dem data further it shows that these transitions may themselves be shaped by floods with 10 to 100 yr recurrence we additionally show that when floodplain width and height above channel bottom are normalized by bankfull width and depth the ratio lies in a narrow range independent of the scale of the river valley

on the history of humans as geomorphic agents the human population has been increasing exponentially simultaneously as digging sticks and antlers have given way to wooden plows iron spades steam shovels and today s huge excavators our ability and motivation to modify the landscape by moving earth in construction and mining activities have also increased dramatically as a consequence we have now become arguably the premier geomorphic agent sculpting the landscape and the rate at which we are moving earth is increasing exponentially as hunter gatherer cultures were replaced by agrarian societies to feed this expanding population erosion from agricultural fields also until recently increased steadily this constitutes an unintended additional human impact on the landscape

evidence for shifting environmental conditions in southwestern france from 33 000 to 15 000 years ago derived from carbon 13 and nitrogen 15 natural abundances in collagen of large herbivores a paleoenvironmental reconstruction of terrestrial environments in southwestern france between 33 and 15 cal kyr bp is provided using 13c and 15n variations in collagen of three herbivorous mammals altogether 161 analyses have been carried out on collagen extracted from skeletal fragments of reindeer horse and bos bison from four successive chronological phases covering the end of mois 3 and mois 2 the 13c values of ungulate collagen are clearly separated between the studied species they are interpreted as reflecting a stable dietary adaptation in a changing environment the variations of 15n values of ungulate collagen are significant especially between specimens from mois 3 and specimens from mois 2 with a minimum during the last glacial maximum this phenomenon seems to reflect changes in the activity of nitrogen cycling processes associated with permafrost development carbon and nitrogen isotopic composition of fossil herbivore collagen are worth investigating as paleoecological and paleoenvironmental tracers in upper pleistocene periglacial continental contexts

southern hemisphere origins of the 1976 climate shift 1 observations from the tropical pacific ocean identify an abrupt climate shift in 1976 with surface temperatures changing from cooler than normal to warmer than normal in the span of about 1 year model results show that this climate shift originates with subsurface temperature anomalies in the south tropical pacific ocean which propagate first to the western boundary then northward to the equator and finally eastward along the equator to 140 w where they rise to the surface the results suggest that changes in the north pacific respond to changes in the tropical pacific

the quaternary of the british isles factors forcing environmental change this paper considers the processes that have controlled cool temperate latitude terrestrial environments over the last ca 3 ma with particular reference to the british isles a scheme is proposed that is based on the processes that act on the land over any given period of time and are the product of climate modulated by rock type the resisting agent and relief determined by tectonics and antecedent relief forming factors climate is generalised in terms of the range and rates of climate change determined by orbital forcing during precession cycles climate change was small and insolation levels were forced by chemically and biologically driven processes the period of obliquity cycles is characterised by patterns of climate change in which physical processes became effective and high magnitude fluvial and slope processes were reinforced by periglaciation and glaciation in susceptible regions eccentricity cycles include climate extremes of longer duration and glaciation and periglaciation were the major contributors to landscape change sediment transfer and sediment mixing these climate forced processes produce distinctive landform sediment and soil assemblages characteristic of particular episodes of quaternary time the lags between the successive systems are identified copyright 2010 john wiley sons ltd

the gisp2 δ18o climate record of the past 16 500 years and the role of the sun ocean and volcanoes measured 18o 16o ratios from the greenland ice sheet project 2 gisp2 ice core extending back to 16 500 cal yr b p provide a continuous record of climate change since the last glaciation high resolution annual 18o 16o results were obtained for most of the current millennium a d 818 1985 and record the medieval warm period the little ice age and a distinct 11 yr 18o 16o cycle volcanic aerosols depress central greenland annual temperature 1 5 c maximally and annual 18o 16o for about 4 yr after each major eruptive event on a bidecadal to millennial time scale the contribution of solar variability to holocene greenlandic temperature change is 0 4 c the role of thermohaline circulation change on climate problematic during the holocene is more distinct for the 16 500 10 000 cal yr b p interval analogous to 14c age calibration terminology we express time in calibrated cal yr b p a d 1950 0 cal yr b p the oldest dryas bolling older dryas allerod younger dryas sequence appears in great detail bidecadal variance in 18o 16o but not necessarily in temperature is enhanced during the last phase of lateglacial time and the younger dryas interval suggesting switches of air mass transport between jet stream branches the branched system is nearly instantaneously replaced at the beginning of the bolling and holocene at 14 670 and 11 650 cal yr b p respectively by an atmospheric circulation system in which 18o 16o and annual accumulation initially track each other closely thermodynamic considerations of the accumulation rate temperature relationship can be used to evaluate the 18 o 16o temperature relationship the gisp2 ice layer count years of major gisp2 climate transitions also support the use of coral 14c ages for age calibration

geoarchaeology the four dimensional 4d fluvial matrix and climatic causality abstract geoarchaeology is the application of geological and geomorphological techniques to archaeology and the study of the interactions of hominins with the natural environment at a variety of temporal and spatial scales geoarchaeology in the uk over the last twenty years has flourished largely because it has gone beyond technological and scientific applications over the same period our ability to reconstruct the 3 dimensional stratigraphy of fluvial deposits and the matrix of fluvial sites has increased dramatically because of a number of technological advances these have included the use of lidar laser imaging and radar to produce high resolution digital surface models the use of geophysics particularly ground penetrating radar and electrical resistivity to produce sediment depth models and the use of gis and data visualisation techniques to manipulate and display the data these techniques along with more systematic and detailed sedimentological recording of exposed sections have allowed the construction of more precise 3 dimensional volumetric models of the matrix of artefacts within fluvial deposits additionally a revolution in dating techniques particularly direct sediment dating by luminescence methods has enabled the creation of 4 dimensional models of the creation and preservation of these sites these 4 dimensional models have the ability to provide far more information about the processes of site creation preservation and even destruction and also allow the integration of these processes with independent data sources concerning cultural evolution and climatic change all improvements in the precision of dating fluvial deposits have archaeological importance in our need to translate events from a sequential or geological timeframe to human timescales this allows geoarchaeology to make a more direct contribution to cultural history through the recognition of agency at the individual or group level this data can then form a component of biocomplexity or agent based modelling which is becoming increasingly used in the natural sciences particularly ecology and geomorphology and which can be used to test scenarios including the impact on and response of hominins to abrupt or catastrophic environmental change whilst catastrophic events clearly represent the atypical they can be illuminating in revealing cognitive processes resulting in abandonment coping mitigation and innovation these points are exemplified using two in depth case studies one from the holocene geoarchaeological record of the river trent in central england and the other from the palaeolithic record from rivers in south west britain in the former the interaction between climate change and human activity is illustrated at the year to century timescale whilst in the other the timescale is millennial these case studies have deliberately been chosen to be as different as possible in temporal and spatial scale with the aim of examining the applicability of methodological and theoretical aspects of geoarchaeology lastly the paper considers the problem of scale in geoarchaeology and concludes it is process dependency which ultimately affects the questions we can ask and that questions of human response to climate change are fundamentally a product of materiality and cognitive processes this demands an in depth contextual approach to such questions rather than database driven assertions of causality

geomorphological change detection of an urban meander loop caused by an extreme flood using remote sensing and bathymetry measurements a case study of karoon river iran abstract flooding and flood inundation are key hydrological characteristics of meander loop rivers however the effects of extreme floods on river morphology and spatial patterns of erosion and deposition are poorly understood a detailed geomorphologic change detection and sediment erosion process caused by an extreme flood more than 100 year recurrence interval discharge on 14 apr 2016 was surveyed for a single urban meander loop of the karoon river iran the studied meander loop is located next to the city of the ahavz and has a centerline length of about 14 km the bathymetry in 8892 stable points was measured also the detailed bathymetry layers for before 8 apr 2016 and after 24 apr 2016 the extreme flood event were compared geomorphological change detection gcd results show that in the studied reach about 106 ha of bank erosion was detected with a total volume of approximately 450 600 m3 furthermore total volume of surface lowering and the total volume of surface rising volumes that were obtained were 95421 6 m3 and 98619 0 m3 respectively the talweg length of the studied meander loop decreased about 126 m and the average depth decreased from 3 71 m to 3 14 m after the flood event channel widening as a consequence of the extreme flood was found to be about 21 m 17 the findings of this study indicate that extreme floods play an important role in the sediment budget and morphological evolution of meandering rivers

carbon and nitrogen isotopic composition of red deer cervus elaphus collagen as a tool for tracking palaeoenvironmental change during the late glacial and early holocene in the northern jura france abstract red deer bone collagen from rochedane in the jura france was analysed for carbon and nitrogen isotopic composition the specimens range in 14c age from about 13 000 to 8000 yr bp uncalibrated and cover the late glacial and early holocene a time period during which climatic conditions shifted from periglacial to temperate the carbon isotopic compositions of red deer collagen suggest changes in the vegetation cover around the site that are consistent with other palaeoenvironmental indicators such as the palynological record in the jura the nitrogen isotopic compositions exhibit a large range of around 6 interpreted as reflecting changes in the intensity of n cycling coeval to vegetation changes red deer bone collagen appears thus as a valuable proxy for reconstructing palaeoenvironmental changes in continental western europe during the late glacial and holocene

glacier change in western north america influences on hydrology geomorphic hazards and water quality the glaciers of western canada and the conterminous united states have dominantly retreated since the end of the little ice age lia in the nineteenth century although average rates of retreat varied from strong in the first half of the twentieth century with glaciers stabilizing or even advancing until 1980 and then resuming consistent recession this retreat has been accompanied by statistically detectable declines in late summer streamflow from glacier fed catchments over much of the study area although there is some geographical variation over recent decades glaciers in northwest bc and southwest yukon have lost mass dominantly by thinning with relatively low rates of terminal retreat and glacier fed streams in that region have experienced increasing flows in many valleys glacier retreat has produced geomorphic hazards including outburst floods from moraine dammed lakes mass failures from oversteepened valley walls and debris flows generated on moraines in addition to these hydrologic and geomorphic changes evidence is presented that glacier retreat will result in higher stream temperatures possibly transient increases in suspended sediment fluxes and concentrations and changes in water chemistry with climate projected to continue warming over the twenty first century current trends in hydrology geomorphology and water quality should continue with a range of implications for water resources availability and management and hydroecology particularly for cool and cold water species such as salmonids copyright 2008 john wiley sons ltd

variations in bone collagen δ13c and δ15n values of fauna from northwest europe over the last 40 000 years we report here a signal in the temporal variation of stable isotopes in protein from surviving animal bone in northwest europe over the past glacial cycle there is a change in the average 13c values of fauna in the holocene and there is also a significant reduction in 15n values of herbivore bone collagen towards the end of the last glaciation with a subsequent recovery soon after the start of the holocene this change is observed for several species and is restricted to those regions most affected by the glacial advance comparison with ice core data shows that there is a strong correlation between the average 13c values of three herbivore species and ice core co2 concentration the data presented here show how readily available faunal bone collagen 13c and 15n measurements provide a record of past climate and environmental change on a regional to continental scale

hillslopes rivers plows and trucks mass transport on earth s surface by natural and technological processes the surface of the earth is being transformed by a new force in the form of technological systems and processes that move significant quantities of mass large distances because movement of mass is perhaps the most basic geomorphic process and because the continuing rise of technology appears to characterize a new epoch in earth evolution the anthropocene it is of interest to compare technological and natural mass transport mechanisms a purely dynamical mass action metric representing the product of mass displaced distance moved and mean speed of displacement is used to compare the transport effectiveness of selected systems systems with large mass action tend to be advective and systems with small mass action diffusive local environments are conditioned by mass action through the introduction of transport corridors such as roads and rivers which put constraints on mass transport by embedded diffusive systems advection also subjects local environments to externally determined time scales such as the times for delivery of unit mass of water or sediment to a river mouth and supports the emergence of associated dynamical processes there for example those of human activity or delta construction that are too rapid to be sustained by diffusion most of the world s mass action is generated by the motion of fluids of global or continental extent as in atmospheric circulation or river flow technological mass action exceeds that of all land based geomorphic systems except rivers technological systems with large mass action tend to be comprised of discrete self powered units e g trucks discretization of transported mass reflects the different locomotion strategy required for transport of solids on land compared with the transport requirements of spatially extensive fluids in nature the principle of maximum entropy production may provide a framework for understanding the emergence of advective technological mass transport systems copyright 2010 john wiley sons ltd

effects of hydrological events on morphological evolution of a fluvial system abstract this study quantifies morphological evolution of the dez river iran from 1955 to 2016 the approach uses a sequence of landsat images aerial photos and topographic maps in addition the hydrological data including average daily discharge and yearly maximum discharge at the dezful hydrological station for the period 1955 2016 were used the study reach was divided into 48 meander loops from upstream to downstream active channel width w was determined at 10 m intervals and changes assessed along the study reach of the dez river morphological indices including sinuosity index straight meander length centerline flow length erosion area erodible length channel migration centerline elongation and radius of curvature were calculated in the reach results showed that the study reach of the dez river changed dramatically in response to major floods although the general trend is towards a narrowing of active channel width by 38 in the period 1955 2016 results show that most of the meander loops in the study area extended and expanded between 1989 and 1995 all types of meander change were observed there was a direct correlation between the frequency of hydrological events flood days bigger than 2 years return period and elongation of bends

can carbon 13 in large herbivores reflect the canopy effect in temperate and boreal ecosystems evidence from modern and ancient ungulates abstract local environmental conditions under dense canopy are known to result in depletion in 13c abundance in plants compared to an open land context this canopy effect has been observed in tropical as well as in mid latitude forest ecosystems however the impact of the canopy effect on tissue 13c abundance of temperate and boreal forest dwelling herbivores has not been thoroughly explored nevertheless the canopy effect has been suggested to explain a decrease of about 3 in collagen 13c values in ancient large herbivores from western europe during the forest expansion of the late glacial early holocene period ca 15 000 6000 cal bp some papers have considered the 13c decrease in large herbivore as the main result of global change in atmospheric co2 content a detailed review of 13c values of large herbivores reindeer red deer roe deer and bison from open and closed environments from high and mid latitudes confirm that the canopy effect observed in plants is passed on to their consumers in the paris basin the decline in 13c values of large herbivores at the late glacial early holocene transition around 10 000 years bp appears to be different according to the considered species namely red deer roe deer and large bovines bison and aurochs moreover differences in the pattern of decrease in 13c values are observed in red deer between french northern alps and french jura these differences among species in their isotopic response through time for a given geographical location and within species from different locations suggest variance in ecological responses of species that are associated with the relative use of forested habitat as a result 13c abundances in collagen can be considered as a direct tracker of the degree of closure of the habitat of ancient herbivores

historical changes in channel network extent and channel planform in an intensively managed landscape natural versus human induced effects abstract humans have become major geomorphological agents effecting substantial change in the characteristics of earth s physical landscapes the agricultural midwest of the united states is a region marked by pronounced human influence at the landscape scale humans undoubtedly have strongly influenced critical zone processes including fluvial processes in intensively managed agricultural landscapes yet the exact nature of human alteration of these processes is unknown this study documents historical changes in the extent of the stream channel network and in channel planform within the upper sangamon river basin an intensively managed agricultural watershed in illinois results indicate that the modern channel network is nearly three times more extensive than the channel network in the 1820s most change in drainage density has occurred in headwater portions of the basin where numerous drainage ditches have been added to the network to drain flat uplands no detectable change in channel position is evident between 1940 and 2012 along about 60 of the total length of the sangamon river and its major tributaries nearly 30 of the total length exhibits change related to meander dynamics cutoffs and lateral migration whereas about 8 has changed as a result of channelization channelized sections typically remain straight for decades following human modification supporting the notion that humans produce long lasting catastrophic change in channel planform in this region the findings confirm that humans are effective agents of morphological change in fluvial systems in this intensively managed watershed documenting human induced versus natural changes in fluvial systems is important for evaluating how other critical zone processes in intensively managed landscapes have been affected by these changes human induced changes in channel extent and planform most likely have altered this landscape from one dominated by biogeochemical transformations and storage of water and sediment prior to agricultural development into one now characterized by enhanced fluxes of water sediment and nutrients

climate science himalayan glaciers in the balance a measurement by satellite altimetry shows the himalayan glaciers to be losing mass at only moderate rates but raises broader questions about other methods for estimating mass balance see letter p 495

preparation and characterization of bone and tooth collagen for isotopic analysis abstract criteria are presented for the identification of diagenetic alteration of carbon and nitrogen isotope ratios of bone and tooth collagen prepared by a widely used method measurements of collagen concentrations in tooth and bone atomic c n ratios and carbon and nitrogen concentrations in collagen of 359 historic and prehistoric african humans and modern and prehistoric east african non human mammals are described carbon isotope ratios of collagen lipids from four bones are also presented compared to bone whole teeth have significantly lower collagen concentrations lower carbon and nitrogen concentrations in collagen and similar c n ratios carbon and nitrogen concentrations and c n ratios are relatively constant over a wide range of collagen concentrations however prehistoric specimens with very low collagen concentrations have highly variable c n ratios very low carbon and nitrogen concentrations in collagen and stable carbon and nitrogen isotope ratios unlike collagen at the transition from well preserved to poorly preserved collagen the most reliable indicator of collagen preservation is the concentration of carbon and nitrogen in collagen concentrations of c and n drop abruptly by an order of magnitude at this transition point these attributes provide simple criteria for assessing sample quality since collagen preservation can vary greatly within prehistoric sites these attributes should be reported for each specimen use of purification procedures that remove acid and base soluble contaminants and particulate matter carbonates fulvic acids lipids humic acids sediments and rootlets are recommended wider adoption of these procedures would insure comparability of results between laboratories and permit independent and objective evaluation of sample preservation and more precise dietary climatic and habitat interpretations of collagen isotopic analyses

tropical glacier meltwater contribution to stream discharge a case study in the cordillera blanca peru original abstract discharge measurements climate observations and hydrochemical samples gathered monthly 1998 99 in the yanamarey and uruashraju glacier fed catchments of the cordillera blanca peru permit an analysis of the glacier meltwater contribution to stream flow these glacier catchments feed the rio santa which discharges into the pacific ocean based on a water balance computation glacier melt contributes an estimated 35 of the average discharge from the catchments for comparison a volumetric end member mixing model of oxygen isotopes shows glacier melt contributes 30 45 to the total annual discharge based on stream geochemistry discharge from the yanamarey glacier catchment provides 30 of the annual volume discharged from the querococha watershed which is 10 glacierized by analogy the larger rio santa watershed also 10 glacierized receives at least 12 of its annual discharge from melting glacier ice tributary watersheds to the rio santa with larger fractions of glacier cover have less variable runoff and enhanced discharge demonstrating that the glaciers effectively buffer stream discharge seasonally with continued glacier melting stream flow will likely become more variable and there will be less dry season runoff

brown bear ursus arctos l palaeoecology and diet in the late pleistocene and holocene of the nw of the iberian peninsula a study on stable isotopes abstract in this paper we performed stable isotope analysis on bone collagen of 81 samples from at least 39 brown bears ursus arctos dating from late pleistocene to nowadays that lived in the western of the cantabrian mountains to interpret the data obtained we compared brown bear stable isotope signatures with those of cave bears ursus spelaeus red deer cervus elaphus and humans homo sapiens from the same area we observed that the diet of cave bears and brown bears in the cantabrian mountains was based on vegetable matter although their different isotopic signatures suggest different ecological niches wooded lowlands for the cave bear and steep highlands with scarce tree cover for the brown bear in the holocene brown bear maintains isotopic signatures similar to the pleistocene ones in spite of the climatic tempering which seems to be related to an even greater displacement toward the uplands due to a greater anthropic pressure in the ecosystem

a stable isotope study of fossil mammal remains from the paglicci cave southern italy n and c as palaeoenvironmental indicators a set of 102 tooth and bone samples of pleistocene age 32 600 13 300 yr bp belonging to the species cervus elaphus bos primigenius and equus caballus and coming from the paglicci cave southern italy was studied for the carbon 13c and nitrogen 15n isotopic composition of bone and dentine collage and for the carbon 13cc isotopic composition of tooth enamel carbonate the amount of collagen extracted from bone and tooth samples mg g was rather variable representing approximately only 0 5 15 of the collagen present in a fresh bone however the loss of an important fraction of the original collagen during diagenesis did not change the in vivo isotopic composition in general when the 13c of both collagen and carbonate and the 15n of collagen obtained from each level for the three species are compared wild ox shows the most increased values deer the most decreased values and horse shows intermediate results these differences are probably related to distinct diets or to differences in their physiological behaviour however the isotopic results suggest that the three species considered lived in an open environment with a diet based on c3 plants the stratigraphic sequence of light and heavy nitrogen isotope values between 19 000 and 15 000 may be related to shifts from arid to humid conditions while the overall trend shown by 13c toward lighter values may be related to a progressive development of a forest habitat

sedimentology of a fine grained aggrading floodplain abstract historical land use changes accelerated both soil erosion and subsequent floodplain alluviation within the galena river basin wisconsin a cross valley transect in a low gradient downstream section of this watershed permitted documentation of the lateral and vertical sedimentological properties occurring during this aggradational phase mechanical and statistical analyses of 97 sediment samples reveal two dominant controls determining the resulting floodplain sedimentology firstly the initial fine grained loessial texture dominated the particle size of the early post settlement alluvium generally yielding fine textured sediments across the valley bottom further landscape de stabilization promoted upland gullying into coarser textured residuum below the loess with a concomitant particle size increase in the foodplain alluvium thus the resulting foodplain stratigraphy exhibits a coarsening upward sequence secondly distance from the stream channel exerts a strong control on overall sedimentological properties distal settings possess massive high clay content sediments usually with less than 1 sand samples become coarser and more stratified near the modern stream channel with channel fill facies containing approximately 20 sand in the upper sections the fine grained loessial sediment source affected numerous sedimentological properties of the deposited alluvium sorting correlates negatively with particle size because all particle sizes were entrained during large overbank floods dominance of silt in this loess mantled basin maintains the maintains the median of the particle size distribution within a fairly narrow range only the tails of the distribution vary and they are primarily controlled by the distance to the stream channel in distal settings the fine tail emerges whereas the coarse tail appears in the channel fill and proximal settings although all sediments were deposited in an overbank floodplain environment passega s cm diagrams erroneously indicate a pelagic depositional environment

nitrogen isotope analyses of reindeer rangifer tarandus 45 000 bp to 9 000 bp palaeoenvironmental reconstructions abstract pleistocene faunal 15 n variations are thought to reflect changes in climatic and environmental conditions researchers are still unclear however which climatic environmental parameter is the primary control on pleistocene faunal 15 n values through extensive nitrogen isotope analysis of late pleistocene reindeer rangifer tarandus collagen we investigated whether permafrost development during the late pleistocene coincided with changes in 15 n values after 45 ka bp reindeer 15 n declined with lowest 15 n values observed after the last glacial maximum lgm between 15 and 11 ka bp the decline in 15 n appears to be of a greater magnitude in more northern regions than in the south of france a pattern similar to that previously observed for horse on a global scale ecosystem 15 n is controlled by the relative openness of the nitrogen cycle which in turn is controlled by climate low soil and plant 15 n are observed in cold and or wet regions and high 15 n are seen in hot and or arid areas the regional pattern in reindeer 15 n decline mimics the pattern of climatic deterioration in europe culminating at the lgm with climate cooling being more intense in northern europe than in southern europe however the lowest reindeer 15 n values are observed after temperatures started to rise this may have been due to a lag in the response of the nitrogen cycle to increasing temperatures alternatively it may have been linked to the influence of permafrost degradation on soil and plant 15 n and thus faunal 15 n the renewed climatic cooling during the younger dryas did not see a fall in reindeer 15 n limited data does however suggest a post younger dryas depletion in reindeer 15 n values

the natural and human structuring of rivers and other geomorphological systems a tribute to william l graf this special issue honors the contributions of william l graf to geomorphology and river science a hallmark of will s work over the course of his career has been a focus on the natural and human structuring of river systems more broadly will has been an innovator and leader who has shaped the way in which geomorphologists conduct research through his work he has made fundamental contributions to basic fluvial theory to the understanding of human impacts on river systems and to policy relevant science he has demonstrated by example how to pursue policy relevant science and to participate in science based policy formulation his contributions to river science can be classified into several themes 1 the hydrology and geomorphology of suburban drainage systems 2 riparian vegetation and river systems 3 the spatial structure and dynamics of incised channels 4 the dynamics of dryland river systems 5 heavy metals in river systems 6 dams and dam removal and 7 water and public policy the papers in this special issue reflect many aspects of these themes and address topics related to 1 the understanding of rivers and other geomorphic systems in the midst of dynamic physical change 2 human influences on geomorphic processes 3 the intersection of geomorphology and public policy and 4 the fusion of geomorphic analysis and giscience

mass loss on himalayan glacier endangers water resources 1 ice cores drilled from glaciers around the world generally contain horizons with elevated levels of beta radioactivity including 36 cl and 3 h associated with atmospheric thermonuclear bomb testing in the 1950s and 1960s ice cores collected in 2006 from naimona nyi glacier in the himalaya tibet lack these distinctive marker horizons suggesting no net accumulation of mass ice since at least 1950 naimona nyi is the highest glacier 6050 masl documented to be losing mass annually suggesting the possibility of similar mass loss on other high elevation glaciers in low and mid latitudes under a warmer earth scenario if climatic conditions dominating the mass balance of naimona nyi extend to other glaciers in the region the implications for water resources could be serious as these glaciers feed the headwaters of the indus ganges and brahmaputra rivers that sustain one of the world s most populous regions

measuring glacier surface temperatures with ground based thermal infrared imaging spatially distributed surface temperature is an important yet difficult to observe variable for physical glacier melt models we utilize ground based thermal infrared imagery to obtain spatially distributed surface temperature data for alpine glaciers the infrared images are used to investigate thermal microscale processes at the glacier surface such as the effect of surface cover type and the temperature gradient at the glacier margins on the glacier s temperature dynamics infrared images were collected at cuchillacocha glacier cordillera blanca peru on 23 25 june 2014 the infrared images were corrected based on ground truth points and local meteorological data for the control points the pearson s correlation coefficient between infrared and station temperatures was 0 95 the ground based infrared camera has the potential for greatly improving glacier energy budget studies and our research shows that it is critical to properly correct the thermal images to produce robust quantifiable data

floodplain sedimentation in the upper mississippi valley natural versus human accelerated abstract understanding the time scales and pathways for response and recovery of rivers and floodplains to episodic changes in erosion and sedimentation has been a long standing issue in fluvial geomorphology floodplains are an important component of watershed systems because they affect downstream storage and delivery of overbank flood waters and they also serve as sources and temporary sinks for sediments and toxic substances delivered by river systems here 14c and 137cs isotopic dating methods are used along with ages of culturally related phenomena associated with mining and agriculture to determine rates of sedimentation and morphologic change for a reach of the upper mississippi river and adjacent tributaries in southwestern wisconsin and northwestern illinois the most important environmental change that influenced fluvial activity in this region during last 10 000 years involved the conversion of a late holocene mosaic of prairie and forest to a landscape dominated by cropland and pastureland associated with euro american settlement results presented herein for the upper mississippi valley umv show that the shift from pre agriculture natural land cover to landscape dominance by agricultural land use of the last 175 200 years typically increased rates and magnitudes of floodplain sedimentation by at least an order of magnitude accelerated overbank flooding led to increased bank heights on tributary streams and in turn contributed to more frequent deep flows of high energy these high energy flows subsequently promoted bank erosion and lateral channel migration and the formation of a historical meander belt whose alluvial surface constitutes a new historical floodplain inset against the earlier historical floodplain the new historical floodplain serves as a flume like channel that provides efficient downstream transport of water and sediment associated with moderate and large magnitude floods floodplains on lower tributaries however continue to experience rates of overbank sedimentation that are of anomalously high magnitude given improved land cover and land conservation since about 1950 this lower valley anomaly is explained by minimal development of historical agriculture period meander belts because of relatively low stream power in these channel and floodplain reaches of relatively low gradient in general long term pre agriculture rates of vertical accretion between about 10 000 and 200 years ago averaged about 0 2 mm yr 1 in tributary watersheds smaller than about 700 km2 and about 0 9 mm yr 1 on the floodplain of the upper mississippi river where the contributing watershed area increases to about 170 000 km2 on the other hand rates of historical vertical accretion during the period of agricultural dominance of the last 200 years average between 2 and 20 mm yr 1 with short episodes of even higher rates during times of particularly poor land conservation practices significant hydrologic effects of mining and agricultural started by the 1820s and became widespread in the study region by the mid 19th century the hydrologic and geomorphic influences of mining were relatively minor compared to those related to agriculture high resolution dating of floodplain vertical accretion deposits shows that large floods have frequently provided major increments of sedimentation on floodplains of tributaries and the main valley upper mississippi river the relative importance of large floods as contributors to floodplain vertical accretion is noteworthy because global atmospheric circulation models indicate that the main channel upper mississippi river should experience increased frequencies of extreme hydrologic events including large floods with anticipated continued global warming instrumental and stratigraphic records show that coincident with global warming a shift to more frequent large floods occurred since 1950 on the upper mississippi river and these floods generally contributed high magnitudes of floodplain sedimentation

human topographic signatures and derived geomorphic processes across landscapes abstract the earth s surface morphology in an abiotic context is a consequence of major forcings such as tectonic uplift erosion sediment transport and climate recently however it has become essential for the geomorphological community to also take into account biota as a geomorphological agent that has a role in shaping the landscape even if at a different scale and magnitude from that of geology although the modern literature is flourishing on the impacts of vegetation on geomorphic processes the study of anthropogenic pressures on geomorphology is still in its early stages topography emerges as a result of natural driving forces but some human activities such as mining agricultural practices and the construction of road networks directly or indirectly move large quantities of soil which leave clear topographic signatures embedded on the earth s morphology these signatures can cause drastic changes to the geomorphological organization of the landscape with direct consequences on earth surface processes this review provides an overview of the recent literature on the role of humans as a geological agent in shaping the morphology of the landscape we explore different contexts that are significantly characterized by anthropogenic topographic signatures landscapes affected by mining activities road networks and agricultural practices we underline the main characteristics of those landscapes and the implications of human impacts on earth surface processes the final section considers future challenges wherein we explore recent novelties and trials in the concept of anthropogenic geomorphology herein we focus on the role of high resolution topographic and remote sensing technologies the reconstruction or identification of artificial or anthropogenic topographies provides a mechanism for quantifying anthropogenic changes to landscape systems this study may allow an improved understanding and targeted mitigation of the processes driving geomorphic changes during anthropogenic development and help guide future research directions for development based watershed studies human society is deeply affecting the environment with consequences on the landscape therefore establishing improved management measures that consider the earth s rapidly changing systems is fundamental

climatic warming glacier recession and runoff from alpine basins after the little ice age maximum records of discharge of rivers draining alpine basins with between 0 and 70 ice cover in the upper aare and rhone catchments switzerland for the period 1894 2006 have been examined together with climatic data for 1866 2006 with a view to assessing the effects on runoff from glacierized basins of climatic warming coupled with glacier recession following the little ice age maximum annual runoff from ice free basins reflects precipitation variations rising from minima between 1880 and 1910 to maxima between the late 1960s and early 1980s the more highly glacierized the basin the more runoff mimicked mean may september air temperature during two periods of warming runoff increased gradually from the 1900s rapidly in the 1940s before decreasing to the late 1970s rising runoff levels during the second warming period failed to exceed those attained during the first despite higher summer temperatures although temperatures continued to rise discharge from glacierized basins declined after reaching maxima in the late 1980s to early 1990s in the first warming period rising specific melt rates augmented by increasing precipitation opposed the impact of declining glacier area on runoff although melt continued to increase in the second period enhanced melting even in the exceptionally warm summer of 2003 appears to have been insufficient to offset reducing glacier surface area exposed to melt low or reducing levels of precipitation and increasing evaporation thus runoff from glacierized basins peaked in the late 1940s to early 1950s

climate and habitat reconstruction using stable carbon and nitrogen isotope ratios of collagen in prehistoric herbivore teeth from kenya stable carbon and nitrogen isotope ratios have been determined for tooth collagen of 27 prehistoric herbivores from a rock shelter in the central rift valley of kenya collagen samples whose isotope ratios were not altered by diagenesis were identified using several analytical methods during the later holocene when the climate was as dry or drier than at present the isotopic compositions of individual animals are similar to those of modern individuals of the same species during the earlier holocene when the climate was wetter than at present the 15n and 13c values are lower than those for their modern counterparts when diagenetic factors can be discounted and adequate modern comparative data are available stable isotope analysis of herbivore teeth and bones can be used to evaluate prehistoric climate and habitat conditions

floodplains as a source of fine sediment in grazed landscapes tracing the source of suspended sediment in the headwaters of an intensively managed agricultural landscape abstract the flux of fine sediment within agricultural watersheds is an important factor determining the environmental quality of streams and rivers despite this importance the contributions of sediment sources to suspended sediment loads within intensively managed agricultural watersheds remain poorly understood this study assesses the provenance of fine suspended sediment in the headwater portion of a river flowing through an agricultural landscape in illinois sediment source samples were collected from five sources croplands forested floodplains grasslands upper grazed floodplains and lower grazed floodplains event based and aggregated suspended sediment samples were collected from the stream at the watershed outlet quantitative geochemical fingerprinting techniques and a mixing model were employed to estimate the relative contributions of sediment from the five sources to the suspended sediment loads to account for possible effects of small sample sizes the analysis was repeated with only two sources grazed floodplains and croplands grasslands forested floodplains results based on mean values of tracers indicate that the vast majority of suspended sediment within the stream 95 is derived from erosion of channel banks and the soil surface within areas of grazed floodplains uncertainty analysis based on monte carlo simulations indicates that mean values of tracer properties which do not account for sampling variability in these properties probably overestimate contributions from the two major sources nevertheless this analysis still supports the conclusion that floodplain erosion accounts for the largest percentage of instream sediment 55 75 although grazing occurs over only a small portion of the total watershed area grazed floodplains which lie in close proximity to the stream channel are an important source of sediment in this headwater steam system efforts to reduce fluxes of fine sediment in this intensively managed landscape should focus on eroding floodplain surfaces and channel banks within heavily grazed reaches of the stream

global warming and fluvial geomorphology future global warming has a number of implications for fluvial geomorphology because of changes in such phenomena as rates of evapotranspiration precipitation characteristics plant distributions plant stomatal closure sea levels glacier and permafrost melting and human responses potential changes in rivers are outlined in this review in the context of changes in the intensity of rainfall the activity of tropical cyclones runoff response including that of europe dry lands and high latitude environments and geomorphological reactions including rates of soil erosion in general however much work remains to be done to establish the full range of geomorphological responses that may take place in fluvial systems

contrasting impacts of dansgaard oeschger events over a western european latitudinal transect modulated by orbital parameters abstract terrestrial and marine proxies pollen planktic and benthic foraminiferal oxygen isotopes alkenone and foraminifer derived sea surface temperatures ssts ice rafted debris from images deep sea cores md95 2042 and su81 18 37 n 10 w md99 2331 and md03 2697 42 n 9 w and md04 2845 45 n 5 w show that western european and offshore environments were strongly affected by dansgaard oeschger d o and heinrich h events we concentrate here on latitudinal variability in the forest cover extent and composition of western europe during the succession of d o events showing new pollen records for core md04 2845 and for marine isotopic stages mis 3 and 4 of core md99 2331 in general cold ssts characteristic of greenland stadials were contemporaneous with the expansion of semi desert or steppic vegetation while greenland interstadials were synchronous with the expansion of forest our data reveal that the amplitude of atlantic and mediterranean forest expansions differs for any given d o warming during the glacial period 74 18 ka in the western mediterranean d o 16 17 and d o 8 and 7 corresponding to minima in precession were associated with strong expansion of forest cover contrasting with weak expansion of forest cover during d o 14 and 12 the opposite pattern is revealed at the atlantic sites further north the strongest greenland warmings are recorded for d o 19 11 and 8 this contrasting latitudinal climatic scenario is compared with other northern hemisphere records revealing similarities between the mediterranean climate and the asian monsoon regime which may relate to a summer atmospheric teleconnection between the two regions comparable to the present day situation parallels between mediterranean climate enhancement and peaks in global methane ch 4 during the last glacial period suggest a significant role of monsoon activity in determining ch 4 emission from wetlands

natural streams and the legacy of water powered mills gravel bedded streams are thought to have a characteristic meandering form bordered by a self formed fine grained floodplain this ideal guides a multibillion dollar stream restoration industry we have mapped and dated many of the deposits along mid atlantic streams that formed the basis for this widely accepted model these data as well as historical maps and records show instead that before european settlement the streams were small anabranching channels within extensive vegetated wetlands that accumulated little sediment but stored substantial organic carbon subsequently 1 to 5 meters of slackwater sedimentation behind tens of thousands of 17th to 19th century milldams buried the presettlement wetlands with fine sediment these findings show that most floodplains along mid atlantic streams are actually fill terraces and historically incised channels are not natural archetypes for meandering streams

synchronisation of palaeoenvironmental records over the last 60 000 years and an extended intimate event stratigraphy to 48 000 b2k the intimate protocol for the correlation of marine ice core and terrestrial records is here updated reflecting recent developments in palaeoclimate research originally focussed on last glacial to interglacial transition lgit 22 000 11 500 years b p the intimate group has now extended its study period back to 60 000 years as a first step the intimate event stratigraphy has now been extended to include 8000 48 000 b2k based on a combined ngrip and grip isotope profile against a gicc05 chronology and key tephra horizons from iceland and continental european volcanic sources in this lead article of this intimate special issue we introduce some of the recent achievements of the intimate community and discuss the challenges associated with extending the intimate approach back in time focussing in particular on the chronological problems inherent in comparing different proxy records the intimate approach has thus far been limited predominantly to the north atlantic and australasian regions and we also discuss the potential to extend the intimate protocol beyond these regions

210pb geochronology of flood events in large tropical river systems floodplain sedimentation removes particles from fluvial transport and constructs stratigraphic records of flooding biogeochemical sequestration and other aspects of the environmental history of ri

synchronisation of palaeoenvironmental events in the north atlantic region during the last termination a revised protocol recommended by the intimate group abstract the north atlantic intimate group of the inqua palaeoclimate commission has previously recommended an event stratigraphy approach for the synchronisation of records of the last termination using the greenland grip isotopic record as the regional stratotype and intcal98 for the calibration of radiocarbon dates lowe j j hoek w intimate group 2001 inter regional correlation of palaeoclimatic records for the last glacial interglacial transition a protocol for improved precision recommended by the intimate project group quaternary science reviews 20 1175 1187 here we present a revised protocol for time stratigraphic correlation in the north atlantic region over a more extended time period 30 8 ka this employs the new ngrip isotopic record and associated greenland ice core chronology 2005 gicc05 as the regional stratotype intcal04 for the calibration of radiocarbon dates bayesian based statistical procedures for the construction of age models and tephrochronology to validate correlations between regional site records

landscape evolution valley excavation and terrace development following abrupt postglacial base level fall many high latitude fluvial systems are adjusting to base level changes since the last glaciation channels that experienced base level fall may still be incising often through glacial diamictons tills these tills can be quite competent behaving more like weak bedrock than unconsolidated sediment and erode at a fast pace thus providing a unique opportunity to test models of channel incision and knickpoint migration in transient systems here we integrate light detection and ranging lidar topography strath terrace chronology and numerical modeling to determine knickpoint migration and incision history of the le sueur river in central minnesota usa results indicate that the le sueur river is best modeled as a detachment limited channel with downstream coarsening related to lag clasts from tills playing a critical factor in longitudinal profile development the le sueur river meanders as it incises so we coupled the best fit incision model to a meander model to determine valley excavation history the excavation history was used to determine a natural background erosion rate prior to land use changes associated with settlement and agricultural expansion in the mid 1800s we compared background fine sediment silt and clay erosion rates with historic decadal average annual suspended loads results show that modern fine sediment contributions from sources associated with valley excavation are three times higher than modeled presettlement loads recent changes in hydrology associated with land use and climate change have increased flows in rivers leading to higher sediment loads not just from field erosion but from increased bank and bluff erosion in the deeply incised valleys

the human role in changing river channels abstract direct consequences of the human role where human activity affects river channels through engineering works including channelization dam construction diversion and culverting have been long recognised marsh 1864 thomas 1956 the less obvious indirect effects of point and reach changes occurring downstream and throughout the basin however are much more recently appreciated dating from key contributions by strahler strahler a n 1956 the nature of induced erosion and aggradation in w l thomas ed man s role in changing the face of the earth university of chicago press chicago 621 638 wolman wolman m g 1967 a cycle of sedimentation and erosion in urban river channels geografiska annaler 49a 385 95 schumm schumm s a 1969 river metamorphosis proceedings american society of civil engineers journal hydraulics division 95 255 73 and graf graf w l 1977 the rate law in fluvial geomorphology american journal of science 277 178 191 these are complemented by effects of alterations of land use such as deforestation intensive agriculture and incidence of fire with the most extreme effects produced by building activity and urbanisation changing river channels are most evident in the channel cross section where changes of size shape and composition are now well established with up to tenfold increases or decreases illustrated by results from more than 200 world studies in addition the overall channel planform the network and the ecology have changed specific terms have become associated with changing river channels including enlargement shrinkage and metamorphosis although the scope of adjustment has been established it has not always been possible to predict what will happen in a particular location because of complex response and contingency the ways in which changes in cross section relate to reach and network changes are less clear despite investigations showing the distribution of changes along segmented channels when considering the human role in relation to changing river channels at least five challenges persist first because prediction of the nature and amount of likely change at a particular location is not certain and because the contrasting responses of humid and arid systems needs to be considered modelling is required to reduce uncertainty as was first emphasised by burkham burkham d e 1981 uncertainties resulting from changes in river form american society civil engineers proceedings journal hydraulics division 107 593 610 second feedback effects incorporated within the relationship between changes at channel reach and network scales can have considerable implications especially because changes now evident may have occurred or have been initiated under different environmental conditions third consideration of global climate change is imperative when considering channel sensitivity and responses to threshold conditions fourth channel design involving geomorphology should now be an integral part of restoration procedures this requires fifthly greater awareness of different cultures as a basis for understanding constraints imposed by legislative frameworks better understanding of the ways in which the perception of the human role in changing river channels varies with culture as well as varying over time should enhance application of design for river channel landscapes

the stratigraphic status of the anthropocene the term anthropocene was coined to describe the present geological epoch in which human activity dominates many of the processes acting on the surface of the earth the expression has been widely adopted but remains informal and lacks precise definition there have been several attempts to establish formal stratigraphic markers to define the start of the anthropocene most recently certini and scalenghe certini g and scalenghe r 2011 anthropogenic soils are the golden spikes for the anthropocene the holocene 21 1269 1274 have argued that the best markers are anthropogenic soils and that these may be used to identify the base of the anthropocene in stratigraphic sequences unfortunately soils fail to meet many of the criteria required for the establishment of stratigraphic golden spikes their preservation potential is poor many stratigraphically important environments do not experience pedogenesis and anthrosols do not always provide the stratigraphically lowest marker of human impact in ad

an event stratigraphy for the last termination in the north atlantic region based on the greenland ice core record a proposal by the intimate group it is suggested that the grip greenland ice core should constitute the stratotype for the last termination based on the oxygen isotope signal in that core a new event stratigraphy spanning the time interval from ca 22 0 to 11 5 k grip yr bp ca 19 0 10 0 k 14 c yr bp is proposed for the north atlantic region this covers the period from the last glacial maximum through termination 1 of the deep ocean record to the pleistocene holocene boundary and encompasses the last glacial late glacial of the traditional northwest european stratigraphy the isotopic record for this period is divided into two stadial episodes greenland stadials 1 gs 1 and 2 gs 2 and two interstadial events greenland interstadials 1 gi 1 and 2 gi 2 in addition gi 1 and gs 2 are further subdivided into shorter episodes the event stratigraphy is equally applicable to ice core marine and terrestrial records and is considered to be a more appropriate classificatory scheme than the terrestrially based radiocarbon dated chronostratigraphy that has been used hitherto 1998 john wiley sons ltd

c and n stable isotope measurements on eurasian fossil mammals 40 000 to 10 000 years bp herbivore physiologies and palaeoenvironmental reconstruction abstract seventy seven specimens of fossil upper pleistocene early holocene woolly mammoth reindeer deer and bison from 17 different locations in eurasia have been measured for the nitrogen and carbon stable isotope composition of their collagen and for the carbon stable isotope composition of bioapatite the aim was 1 to check the existence of differences in n and c isotope ratios between and within different herbivore species mainly between mammoth and reindeer 2 to discuss these data in terms of animal physiology temporal and spatial distribution of animals and effects of climatic changes and 3 to obtain further information about the environmental changes that occurred in that area during the period considered a geographical variation from south west to north east in the 15n and or 13c values of collagen and bioapatite for all the herbivore species is apparent the most negative 13c values and the most positive 15n values being located in the north eastern area this was probably due to a different temperature and water stress on animals and plants and to a different plant availability the differences in 13c 12c and 15n 14n isotope ratios among species are mainly related to different food intake and different metabolic pathways it seems also that the diet of mammoths from north eastern siberia was higher in protein content compared with that of mammoths from the russian plain from this study it is clear that there was a rapid and important change in the amount of precipitation soon after the last glacial maximum the rainfall conditions around 40 000 and 30 000 years bp were probably similar to those existing around 10 000 years bp though lower than those existing after the glacial maximum

disturbance stream incision and channel evolution the roles of excess transport capacity and boundary materials in controlling channel response abstract channel incision is part of denudation drainage network development and landscape evolution rejuvenation of fluvial networks by channel incision often leads to further network development and an increase in drainage density as gullies migrate into previously non incised surfaces large anthropogenic disturbances similar to large or catastrophic natural events greatly compress time scales for incision and related processes by creating enormous imbalances between upstream sediment delivery and available transporting power field examples of channel responses to antrhopogenic and natural disturbances are presented for fluvial systems in the mid continent and pacific northwest usa and central italy responses to different types of disturbances are shown to result in similar spatial and temporal trends of incision for vastly different fluvial systems similar disturbances are shown to result in varying relative magnitudes of vertical and lateral widening processes and different channel morphologies as a function of the type of boundary sediments comprising the bed and banks this apparent contradiction is explained through an analysis of temporal adjustments to flow energy shear stress and stream power with time numerical simulations of sand bed channels of varying bank resistance and disturbed by reducing the upstream sediment supply by half show identical adjustments in flow energy and the rate of energy dissipation the processes that dominate adjustment and the ultimate stable geometries however are vastly different depending on the cohesion of the channel banks and the supply of hydraulically controlled sediment sand provided by bank erosion the non linear asymptotic nature of fluvial adjustment to incision caused by channelization or other causes is borne out in similar temporal trends of sediment loads from disturbed systems the sediments emanating from incised channels can represent a large proportion of the total sediment yield from a landscape with erosion from the channel banks generally the dominant source disturbances that effect available force stream power or flow energy or change erosional resistance such that an excess of flow energy occurs can result in incision channel incision therefore can be considered a quintessential feature of dis equilibrated fluvial systems

alluvial sedimentation rates from southeastern australia indicate post european settlement landscape recovery increased catchment sediment yields are common following the introduction of european style agriculture to relatively undisturbed landscapes catchment erosion rates generally increase immediately after disturbance and then decline over time consequently where a catchment currently sits along this disturbance recovery sequence will strongly influence future catchment sediment yields and river morphology in this study field stratigraphy optical dating and hydraulic modelling are used to investigate changes in catchment sediment yield and storage in the lake burragorang catchment in australia with emphasis placed upon changes occurring since european settlement in a d 1820 on the southern tablelands and the upper cox s river subcatchment a large volume of sediment was liberated by gully erosion early in the post settlement period much of which was deposited at break of slope positions below the catchment s headwaters or stored in alluvial benches adjacent to the channel but within the confines of older holocene alluvium a lack of substantial sediment deposition over the last 20 to 40 years is evidence that catchment sediment yields have strongly declined this is consistent with both reduced erosion rates and re aggradation of the incised gullies that in their erosive phase dominated the catchment s post settlement sediment flux collectively these characteristics indicate the catchment is undergoing a phase of landscape recovery

carbon and nitrogen stable isotope analysis of northwest european horse bone and tooth collagen 40 000 bp present palaeoclimatic interpretations abstract carbon and nitrogen stable isotope ratios of bone and tooth dentine collagen from 142 horses were analysed to consider the potential of isotopic analysis of faunal remains as a palaeoenvironmental and palaeoclimatic proxy a general trend through time towards lighter 13 c values was observed but with an obvious depletion at the late glacial holocene transition horse 13 c values appear to track plant 13 c although phenomenon such as the canopy effect may influence faunal 13 c values we believe that the influence on plants of increasing atmospheric co 2 is the primary factor in the change in faunal 13 c values at the late glacial holocene transition a post glacial depletion in horse 15 n values is observed in areas proximal to glacial retreat although no data is available in these areas during the last glacial maximum horse 15 n values are presumed to reflect plant 15 n values depleted plant nitrogen may be attributed to a number of factors e g water availability temperature cycling of nitrogen in the soil soil nutrient availability especially phosphorus in the post glacial period and the type of mycorrhizal associations formed with plant these effects may be interrelated and be linked such that a positive feedback can give a non linear response to a single parameter

detection of changes in glacial run off in alpine basins examples from north america the alps central asia and the andes atmospheric warming and enhanced melting of glaciers is already resulting in changes in the glacial contribution to run off in mountain basins around the world the enhanced melting of glaciers leads at first to increased run off and discharge peaks and an increased melt season while in the longer time frame glacier wasting can be so severe that it results in decreased run off glacier basins with a decreasing run off trend have been observed in south central british columbia at low elevations in the swiss alps and in the central andes of chile which is probably a combined effect of reduced melt from seasonal snow cover as the snow line rises and relevant glacier area losses in contrast significant run off increases are reported in alberta north western british columbia and yukon in canada in highly glacierized basins in the swiss and austrian alps the tianshan mountains and tibet in central asia and in the tropical andes of peru the run off increase within these basins is closely related to observed temperature rise indicating that there is an unequivocal signal of enhanced glacier melting under the present warming trends in future warming scenarios glacier run off should start to decrease even in high altitude basins affecting water availability copyright 2008 john wiley sons ltd

the anthropocene is there a geomorphological case the anthropocene as used to describe the interval of recent earth history during which humans have had an overwhelming effect on the earth system is now being formally considered as a possible new geological epoch such a new geological time interval possibly equivalent to the pleistocene epoch requires both theoretical justification as well as empirical evidence preserved within the geological record since the geological record is driven by geomorphological processes that produce terrestrial and near shore stratigraphy geomorphology has to be an integral part of this consideration for this reason the british society for geomorphology bsg has inaugurated a fixed term working group to consider this issue and advise the society on how geomorphologists can engage with debates over the anthropocene this esex commentary sets out the initial case for the formalisation of the anthropocene and a priori considerations in the hope that it will stimulate debate amongst and involvement by the geomorphological community in what is a crucial issue for the discipline the working group is now considering the practical aspects of such a formalization including the relative magnitude problem the boundary problem and the spatial diachrony of anthropogenic geomorphology copyright 2013 john wiley sons ltd

carbon and nitrogen stable isotopes of bone collagen of large herbivores from the late pleistocene kiputz ix cave site gipuzkoa north iberian peninsula for palaeoenvironmental reconstruction abstract the kiputz ix site records climatic variations during the late pleistocene since it represents a continuous time interval record ca 25 13 ka cal bp carbon and nitrogen stable isotopes from the bone collagen of herbivores rangifer tarandus cervus elaphus and bison priscus were analysed to establish environmental and climatic conditions in the northern iberian peninsula faunal distribution over time represents a response to climatic variations showing inverse patterns with reindeer and bison profusion during cold periods and red deer abundance during warmer times the increase in reindeer 15 n values during stadial gs 2 appears to be greater in magnitude than in continental europe and reflects drier warmer climatic conditions the 13 c values of red deer suggest more humid environmental conditions south of the pyrenees during interstadial gs 1 the climatic conditions of southern pyrenees appear to be analogous to that of northern pyrenees regions

bone as a stable isotope archive for local climatic information this brief review outlines the contribution that the study of stable isotope composition in bone can make to palaeoclimatic investigation with the focus almost entirely restricted to the last 50 000 years in nw europe bone can provide a useful archive of the prevailing isotopic condition and represents a quite different and often less specialised sampling of the environment than most other archives on the other hand chronological sequences and dating generally can be a problem and the link between the isotopic value registered in the bone and the environmental conditions which gave rise to it is both complex and not fully understood carbon oxygen and nitrogen isotopes are all available from bone nitrogen only where sufficient protein collagen survives and are all subject in different ways to climatic influences such as temperature rainfall changes in floristic composition and soil chemistry these are all briefly discussed and the datasets that are being published are considered in the context of the environmental information they provide undoubtedly environmental signals are recoverable but their interpretation is still primitive a dataset for carbon and nitrogen isotope composition of herbivores that spans the last 50 000 years is shown together with some of the issues it raises

catchment scale cumulative impact of human activities on river channels in the late anthropocene implications limitations prospect abstract evidence for the proposed anthropocene epoch in fluvial geomorphology hinges on the influence of human activities relative to natural forcing however research on cause effect understanding in river channel evolution has rarely focused on the cumulative impact of multiple drivers for change limiting insights systematic review of 25 recent studies professing to explain reach scale channel responses to cumulative impacts of human activities and natural forcing over the recent past ca 1880 2005 reveals some consistencies in spatio temporal response across various catchment sizes median 3000 km2 in mostly industrialized nations common drivers for change include changing flood and flow regimes dam construction changing land uses and forest cover bank protection and instream aggregate mining recent channel evolution has predominantly involved narrowing incision and terrace development reduced bed sediment storage lower activity rates and simplified channel geometries rates of channel change frequently peaked 1955 1990 providing some support for the anthropocene great acceleration evidence here suggests that many river systems are now in morphologically novel configurations coinciding temporally with dramatic recent declines in global freshwater aquatic biodiversity sustainable approaches to freshwater management must acknowledge these configurations placing emphasis on process based approaches to river ecosystem health in which sediment cascades are reconceived to reflect altered longitudinal and lateral connectivity however the reviewed studies are driven largely by expert judgment depicting cause effect associations through summary conceptual models based on spatial proximity and temporal synchronicity providing insufficient scientific proof for the anthropocene based on the overwhelming impact of human factors more conclusive cause effect statements will require hypothetic deductive approaches explicit functional criteria and best practice environmental model building geomorphologists should now move beyond the phase of discovery and develop rigorous proofs for cause effect relationships of cumulative impact this may be enhanced by developing an avowedly anthropocene perspective in which rivers are viewed critically as socio biophysical systems co evolving with human activity

toward hydro social modeling merging human variables and the social sciences with climate glacier runoff models santa river peru summary glacier shrinkage caused by climate change is likely to trigger diminished and less consistent stream flow in glacier fed watersheds worldwide to understand model and adapt to these climate glacier water changes it is vital to integrate the analysis of both water availability the domain of hydrologists and water use the focus for social scientists drawn from a case study of the santa river watershed below peru s glaciated cordillera blanca mountain range this paper provides a holistic hydro social framework that identifies five major human variables critical to hydrological modeling because these forces have profoundly influenced water use over the last 60 years 1 political agendas and economic development 2 governance laws and institutions 3 technology and engineering 4 land and resource use and 5 societal responses notable shifts in santa river water use including major expansions in hydroelectricity generation large scale irrigation projects and other land and resource use practices did not necessarily stem from changing glacier runoff or hydrologic shifts but rather from these human variables ultimately then water usage is not predictable based on water availability alone glacier runoff conforms to certain expected trends predicted by models of progressively reduced glacier storage however societal forces establish the legal economic political cultural and social drivers that actually shape water usage patterns via human modification of watershed dynamics this hydro social framework has widespread implications for hydrological modeling in glaciated watersheds from the andes and alps to the himalaya and tien shan as well as for the development of climate change adaptation plans