an evaporitic facies in neoproterozoic post glacial carbonates the gifberg group south africa abstract a geological study of the hitherto poorly described neoproterozoic gifberg group with emphasis on lithogeochemistry and o c and sr isotopic composition of the carbonate dominated widouw formation vredendal outlier westernmost south africa revealed that the entire group is an equivalent of the relatively well constrained port nolloth group in the external paraautochthonous part of the pan african gariep belt further north thus the vredendal outlier can be regarded as the southern extension of the port nolloth zone two diamictite units are recognised in the vredendal outlier which can be correlated respectively with the c 750 ma kaigas formation diamictite and the 583 ma syn gaskiers numees formation diamictite in the gariep belt proper the dominating carbonate unit in the studied area is post glacial with respect to the older of the two diamictite units the combined textural structural and geochemical evidence suggests that parts of the variably dolomitised limestone succession represent former evaporite beds sedimentation in a restricted very shallow and proximal basin led to a wide range in c isotope ratios 13cpdb from 4 2 to 4 8 very high sr concentrations derived from original anhydrite and initial 87sr 86sr ratios that are significantly higher 0 70785 than those of coeval seawater as c and sr isotopes are commonly used for chemostratigraphic correlation and high sr concentrations in neoproterozic carbonates are often interpreted as evidence of former aragonite the findings of this study should be used as warning against uncritical use of geochemical and isotopic parameters for describing ancient seawater composition thus c and sr isotope ratios alone in neoproterozoic carbonates may be less powerful proxies of ancient seawater composition and high sr contents are not necessarily indicative of an aragonite sea as previously inferred

fluvial development and the sediment regime of the lower calder ribble catchment northwest england in the lower reaches of the calder lancashire tributary of the ribble catchment northwest england five river terraces set into the surrounding glacial terrain have been mapped and their underlying sediments radiocarbon dated the earliest terrace t1 reflects sandur style deposition during deglaciation and it aggraded in a reach cut into glacial diamict and glaciolacustrine muds incision below t1 spanned the start of the holocene driven by a combination of reduced sediment supply under a stabilising landscape and lower base levels t2 had aggraded and was being abandoned by 4000 bc its formation latterly involving a period of comparative stability in terms of channel migration perhaps a function of extensive forest cover and sea levels reaching above present day levels the last 3000 years were marked by substantial changes in the sedimentary regime with increased and varying sediment supply driving cycles of cut and fill and greater lateral channel migration these changes coincided with the first widespread and substantial reductions in forest cover and a progression towards an agricultural landscape between the aggradation of terraces t3 and t4 there was a substantial increase in sediment supply which is broadly in keeping with the erosion history in the surrounding uplands this sediment slug appears to have induced a switch from highly sinuous meandering to lower sinuosity channels characterised by lateral scroll style migration late holocene vegetation changes particularly woodland removal driven by anthropogenic land pressure appear to have rendered the floodplain prone to channel migration and the landscape more susceptible to erosion

changes in hydrologic regime by dams dams have major impacts on river hydrology primarily through changes in the timing magnitude and frequency of low and high flows ultimately producing a hydrologic regime differing significantly from the pre impoundment natural flow regime this paper presents the analysis of pre and post dam hydrologic changes from dams that cover the spectrum of hydrologic and climatic regimes across the united states our overall goals are to document the type magnitude and direction of hydrologic shifts because of impoundment using the entire database for the national inventory of dams nid for dams possessing longstanding u s geological survey usgs gages downstream we identified 21 gage stations that met length of record criteria encompassing an array of types of dams and spanning four orders of magnitude in contributing watershed area to assess hydrologic changes associated with dams we applied a hydrologic model the indicators of hydrologic alteration iha supplemented with orientation statistics for certain hydrograph parameters dams had significant impacts on the entire range of hydrologic characteristics measured by iha for many characteristics the direction and significance of effects were highly consistent across the 21 sites the most significant changes across these sites occurred in minimum and maximum flows over different durations for low flows the 1 day through 90 day minimum flows increased significantly following impoundment the 1 day through 7 day maximum flows decreased significantly across the sites at monthly scales mean flows in april and may tend to decline while mean flows in august and september increase other significant adjustments included changes in annual hydrograph conditions primarily in the number of hydrograph reversals that has generally increased for almost all sites following impoundment the number of high pulses has increased following impoundment but the average length declines the mean rate of hydrograph rise and fall has declined significantly these results indicate that the major pulse of dam construction during the previous century has modified hydrologic regimes on a nationwide scale for large and small rivers

neoproterozoic tectono thermal evolution of the gariep belt and its basement namibia and south africa abstract within the pan african gariep belt in southwestern africa a para autochthonous predominantly sedimentary sequence deposited in a rift graben and subsequently on a passive continental margin with a kibaran basement is distinguished from an allochthonous predominantly oceanic terrane that was thrust on top of the former during collision of the rio de la plata and the kalahari plates 40ar 39ar mineral cooling ages presented here set the following constraints after kibaran high grade metamorphism the consolidated basement cooled through 300 c at 1006 ma rifting between 781 and 741 ma was followed by the formation of oceanic crust the lower parts of which cooled through 500 c sometime between 630 and 600 ma after inversion from extension to compression some of the oceanic crustal material was shredded off and incorporated into an accretionary wedge a process that is indirectly dated between 573 576 ma by hornblende plateau ages continent continent collision and thrusting of the internal onto the external zones of the tectonic belt culminated between 547 543 ma as indicated by further hornblende plateau ages muscovite cooling ages for the internal zone are between 526 and 529 ma those for the tectonically deeper external zone are 483 ma in the north and between 495 506 ma in the south of the belt in conjunction with published data these results suggest successive closure of first the northern adamastor ocean kaoko belt followed by the khomas sea intracontinental damara belt and finally the southern adamastor ocean gariep belt

geomorphology within the interdisciplinary science of environmental flows article i nfo the field tradition in geomorphology informs beyond studying landforms by also providing a stage for understand ing how geomorphic elements influence the ecology of biota the intersection between fluvial geomorphology and riverine ecology represents an ideal confluence to examine the contribution of the geomorphic field tradition to en vironmental flows and show this area of riverine management as a research frontier for applied geomorphology environmental flows have consisted of a set of ecological based stream flow guidelines designed to inform sustain able water resource management that supports healthy riverine habitats and provides sufficient water supply for society geomorphological understanding is central to environmental flows because it is the interaction between flow form and substrate that influences habitat type condition availability and biotic use across space and time this relationship varies longitudinally laterally vertically overtime and across macro to mesoscale morphologies withintheriverine environment thegeomorphictemplateis therefore asintegralasthe flow wereviewedstudies where field evidence indicated that geomorphology impacts the effectiveness of environmental flow strategies and wemakethecasefortheneedtoincreasegeomorphic considerationsinenvironmental flows although flow iscom monly referred toas themaster variablein environmental flows geomorphologymediatestheeffectsof flow regime on ecological processes concepts and applications from this perspective on the role of geomorphology in riverine ecosystem research will inform the practice policy and implementation of environmental flows

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

zoogeomorphology in the anthropocene abstract the anthropocene embodies the concept of human impacts on the natural environment but disagreements exist as to when to identify its inception starting date in this paper i illustrate that regardless of the proposed starting date of the anthropocene important zoogeomorphic impacts were initiated at each of these proposed starting dates humans have profoundly altered geomorphic pathways through extinctions and the near extirpation of native populations of animal species that strongly influenced hydrology and removal of surface sediment and through the introduction of populations of animals that bring to bear a suite of different geomorphic effects on environmental systems domestication of animals brought its own suite of zoogeomorphic implications introductions of exotic species and the spread of feral species often led to dramatic new geomorphic landscapes because of the absence of natural controls on population expansion in the mountains of the western usa and elsewhere the geomorphic actions of animals are being impacted by human induced climate change climate change in some cases affects the spatial pattern and range of species whereas in other cases it may lead to the extirpation of species with zoogeomorphic impacts

geology of the cenozoic namakwa sands heavy mineral deposit west coast of south africa a world class resource of titanium and zircon exploration for heavy minerals along the coastal strip of southwest africa led to the discovery and subsequent delineation of the namakwa sands deposit near brand se baai in 1987 currently tronox limited controls the namakwa sands operation which has developed into a significant global producer of titanium slag pig iron ceramics quality zircon and rutile concentrates the namakwa sands deposit is classified as a megaresource with 1 17 billion tons bt of in situ ore containing an estimated 92 6 million metric tons mt of total heavy minerals and the equivalent of 23 9 mt tio2 units and 9 4 mt zircon the siliciclastic arenaceous deposit is divided into two adjacent orebodies referred to as graauwduinen west and graauwduinen east the graauwduinen west orebody consists of three strandline dune couplets set in a transitional shallow marine aeolian environment whereas the graauwduinen east orebody comprises a largely unrelated dune deposit superimposed onto the ore bearing sequence is a pseudostratigraphy of duricrust that effectively cemented the bulk of the mineralized sands to various degrees of hardness the two orebodies are profoundly different in many aspects spatially the planar mineralization bears northeasterly in the graauwduinen west orebody strikingly perpendicular to the southeasterly trend observed in the graauwduinen east orebody contrasts in their bulk chemistry and mineralogy are statistically significant the graauwduinen west orebody features noticeably better total heavy mineral grades accompanied by conspicuously high proportions of the gangue minerals garnet and pyroxene the valuable mineral fraction is predominated by ilmenite fetio3 followed in abundance by zircon zrsio4 leucoxene an alteration product of ilmenite and rutile tio2 their geochemistry mineralogy and petrography are extremely variable but the bulk of the current valuable mineral fraction is recoverable to premium grade products the proximal mesoproterozoic namaqualand metamorphic province is considered the main contributor to the current heavy mineral population the graauwduinen west orebody received source sediment via established fluvial marine courses whereas the source of the graauwduinen east orebody is considered to originate from a distinct fluvial aeolian corridor the genesis of the namakwa sands deposit is strongly entrenched in the geomorphic evolution of the west coast of southern africa since the cenozoic which was driven by regional tectonism fluctuating sea levels and alternating climatic patterns

human impact on land ocean sediment transfer by the world s rivers abstract land ocean transfer of sediment by rivers is a key pathway for material transfer on earth contemporary data on the sediment loads of rivers provide clear evidence of significant recent changes in the sediment fluxes of several rivers in response to human impact the key drivers of increased sediment loads include land clearance for agriculture and other facets of land surface disturbance including logging activity and mining although programmes for soil conservation and sediment control can result in reduced sediment loads the trapping of sediment by dams represents the dominant cause of reduced loads this influence is currently assuming increasing importance at the global scale any attempt to link these drivers to changes in the global land ocean sediment flux must take account of the aggregation and buffering effects that operate in larger basins which can cause damping and even removal of signals of increasing flux within the upstream basin and complicate the link between upstream and downstream response to human impact further work is required to provide a precise quantitative assessment of the human impact on global land ocean sediment fluxes and the net effect of increasing and decreasing fluxes particular attention must be paid to the temporal perspective and the variation of impact trajectories in different areas of the globe and for river basins of different sizes

human impact on the hydroenvironment of lake parishan sw iran through the late holocene a multiproxy record from lake parishan sw iran shows human impact on the lake and its catchment over the last 4000 years the parishan record provides evidence of changes in lake hydrology from ostracod diatom and isotope analyses that are directly linked to human activity in the catchment recorded by pollen and charcoal and supported by regional archaeological and historical data the lake ostracod fauna is particularly sensitive to human induced catchment alterations and allows us to identify changes in catchment hydrology that are due to more than a simple change in precipitation evaporation state oxygen isotope data from endogenic carbonates follow these faunal changes but also display a longer trend to more positive values through the period coincident with regional patterns of water balance for the late holocene in the eastern mediterranean

holocene environmental change and its impact on sediment dynamics in the eastern mediterranean abstract investigators have studied past environmental change in the eastern mediterranean region from a number of perspectives while climate reconstructions and palynological research have focused on forces that drive the geomorphologic system many researchers have attempted to use sediment archive studies to identify periods of change in sediment dynamics due to the large variability in environmental parameters and the variety of landscapes present in the eastern mediterranean region research has focused on sediment archives ranging from small colluvial sites to deltas of large rivers on the mediterranean coast as the cultural record for the region is extremely rich the main goal of palaeo environmental research in the eastern mediterranean has been to identify the relative importance of human impact on the landscape nevertheless sediment archives have significant limitations chronological control for many palaeo environmental records is highly uncertain and rates of landscape change are oftentimes difficult to assess most palaeo environmental research has been conducted on or near archeological sites where direct human impact may obscure the indirect impact on sediment dynamics through land use changes quantification and modeling of sediment dynamics in the eastern mediterranean environment offer one solution when erosion and sediment transport rate analyses are incorporated periods of relatively important change can be identified using multiple approaches the relative importance of the main driving forces climate and land use become distinguishable since field based data from the actual sediment archives remain vital an overview of numerous studies in the eastern mediterranean is provided in order to draw a general picture for different time periods and the relative scale of regional landscape development during the holocene a comparison of sediment dynamics with the record of driving forces indicates that while climate was the main driver of the geomorphic system during the early holocene at some point human impact became widespread and began to dictate sediment dynamics to a large extent from the byzantine period onward soil properties seem to play an increasingly important role as the hillslope soil reservoir in the eastern mediterranean was progressively depleted during the late holocene

influences of anthropogenic activities on dissolved silica migration in a granite hosted basin hainan island china abstract the continent ocean transfer of dissolved silica dsi formed as sio2 via rivers constitutes an important part of the global silica cycle the uptake of terrestrial vegetation and riverine phytoplankton are the key process controlling dsi migration within the drainage basin anthropogenic activities including land use change and damming have been altering dsi export by changing biological uptakes in the basin a significant artificial lake effect of damming was exhibited on the spatial variations of chlorophyll a chl a and dsi which caused 15 39 of riverine dsi to be detained in the reservoir region of changhuajiang river basin hainan island china the biological uptake of terrestrial vegetation was behindhand responsible for seasonal fluctuations of dsi the dsi uptake yields ranged from 19 44 t km2 yr to 86 76 t km2 yr during the different terrestrial vegetation types in the basin in turn tropical rainforest crops artificial economic forests grassland the try calculating of the dsi yield released by the silicates weathering was carried out taking biological processes in the basin into account taking into the plants uptake within the basin consideration the corrected dsi yield from the silicates weathering was 18 6 t km2 yr accordingly the silicates weathering rate was up to 41 55 t km2 yr which was 1 36 times higher than that 30 39 t km2 yr without consideration of the biological uptake and close to the fastest weathering rate of the granite basin puerto rico in the earth surface of the dsi released by the silicates weathering 28 56 was absorbed by terrestrial vegetation and 31 43 was consumed by riverine phytoplankton and the rest was drainaged into the south china sea

blame it on the goats desertification in the near east during the holocene the degree to which desertification during the holocene resulted from climatic deterioration or alternatively from overgrazing has puzzled quaternary scientists in many arid regions of the world i

the paleoenvironmental evolution of the cambrian longwangmiao formation stage 4 toyonian on the yangtze platform south china petrographic and geochemical constrains abstract during the cambrian period stage 4 biodiversity and biomass declined rapidly and globally in an event known as the botomian toyonian crisis to gain a better understanding of the paleoenvironment in south china during this stage we present and interpret complex multi parameter carbonate analyses petrography carbon and oxygen isotopic composition and major trace and rare earth elements from the toyonian longwangmiao formation in the bandenggou section the longwangmiao formation comprises primarily carbonate deposits with massive detrital mineral occurrences in its lower middle sequence principal component analysis of the minerals and oxides leads to the definition of two intervals i and ii interval i is composed mainly of dolostones interbedded with sandstones and contains exceedingly high amounts of terrestrial original minerals and oxides as well as high ree y th and sc concentrations interval ii which is composed primarily of limestones has trace amounts of terrestrial original minerals and oxides and low ree y th and sc concentrations the 13c and 18o values show a significant positive shift from interval i to interval ii after eliminating the effects of diagenesis contributions through the analyses of diagenesis sensitive indexes 18o values mgo cao mn sr and fe sr ratios and the correlations of 13c 18o 18o eu eu eu eu ce ce and eu eu feo the sr and na concentrations of calcites in interval i are extremely high exceeding even the corresponding ranges of marine aragonites while calcites from interval ii have low sr and na concentrations that are within the range of marine low mg calcite however both show strong positive correlations between ca sr ca na and sr na the different calcite elemental behaviors in intervals i and ii suggest different carbonate precursors associated with seawater temperature and climate furthermore the sr ca ratios are negatively correlated with 13c and 18o values and the 13c values also negatively correlated with sio2 content these features indicate a significant change in the depositional environment during the cambrian toyonian stage from an early restricted marine environment under a warm and arid climate with massive terrestrial influxes to a later relatively open marine environment under a cool and humid climate with negligible terrestrial influxes this shift likely resulted in the observed changes in biomass and biodiversity

two dimensional time dependent hurricane overwash and erosion modeling at santa rosa island abstract a 2dh numerical model which is capable of computing nearshore circulation and morphodynamics including dune erosion breaching and overwash is used to simulate overwash caused by hurricane ivan 2004 on a barrier island the model is forced using parametric wave and surge time series based on field data and large scale numerical model results the model predicted beach face and dune erosion reasonably well as well as the development of washover fans furthermore the model demonstrated considerable quantitative skill upwards of 66 of variance explained maximum bias 0 21 m in hindcasting the post storm shape and elevation of the subaerial barrier island when a sheet flow sediment transport limiter was applied the prediction skill ranged between 0 66 and 0 77 in a series of sensitivity tests in which several hydraulic forcing parameters were varied the sensitivity studies showed that the variations in the incident wave height and wave period affected the entire simulated island morphology while variations in the surge level gradient between the ocean and back barrier bay affected the amount of deposition on the back barrier and in the back barrier bay the model sensitivity to the sheet flow sediment transport limiter which served as a proxy for unknown factors controlling the resistance to erosion was significantly greater than the sensitivity to the hydraulic forcing parameters if no limiter was applied the simulated morphological response of the barrier island was an order of magnitude greater than the measured morphological response

river response to rapid holocene environmental change evidence and explanation in british catchments macklin m g jones a f lewin j 2010 river response to rapid holocene environmental change evidence and explanation in british catchments quaternary science reviews 29 13 14 1555 1576 sponsorship welsh assembly government and the higher education funding council for wales for funding this study through its support of the centre for catchment and coastal research at aberystwyth university

stream flow changes across north carolina usa 1955 2012 with implications for environmental flow management abstract this study examines changes in stream flow conditions across north carolina relates these changes to geomorphological conditions of rivers and makes recommendations for environmental flow guidelines to conserve and protect riverine ecosystems monthly stream flow percentile metrics 90th 75th 50th 25th and 10th percentiles are compared over two time periods 1955 1980 and 1984 2012 for 63 gages distributed statewide the results showed that stream flow changes vary spatially by flow magnitude ecoregion basin and temporally by months the greatest changes involve decreases to the 10th 25th 50th and 75th percentiles and the least amount of change is associated with 90th percentile flows the spring and summer months of february through august have the greatest flow reductions while september november and december exhibit magnitude increases for the 75th and 90th percentile flows the blue ridge has the least amount of change whereas the piedmont and coastal plain have the greatest change the few gages that do not show significant magnitude decreases to the 10th percentile flow are below major dams on the neuse cape fear and roanoke rivers these same dammed rivers exhibit increases to the 90th percentile flows the tar river basin which is free of dams shows opposite effects with significant decreases to the 10th percentile flows and minimal changes to the 75th and 90th percentile flows this study elucidates the importance of establishing environmental flow criteria that apply statewide across north carolina sustainable environmental flow criteria need to be established that conserve seasonal patterns of flows sustain low flows from increases and decreases and protect headwater and tributary accumulation areas from over abstraction

the fate of soil organic carbon upon erosion transport and deposition in agricultural landscapes a review of different concepts abstract erosion and deposition redistribute large quantities of sediment and soil organic carbon soc in agricultural landscapes in the perspective of global carbon cycling the coupling between erosion processes and the fate of soc is of particular interest however different concepts have been proposed to assess the impact of erosion induced lateral and vertical carbon fluxes on landscape scale this resulted in contrasting conclusions if agricultural soils represent either a carbon sink or source the large global area of arable soil and generally high erosion rates make these insights important in this review we aim to give an overview of the different conceptual relations described governing c dynamics at sites of erosion along the transport pathway and at depositional sites and the current state of knowledge on the fate of soc upon erosion transport and deposition in agricultural landscapes the impact of erosion on soc dynamics differs for sites of erosion deposition and during transport with further influences by agricultural practices e g tillage and fertilisation controlling processes are the detachment of sediment and soc net primary production resulting in dynamic replacement and changes in mineralisation upon transport and deposition due to aggregate breakdown and deep burial respectively however the exact magnitude and dominance of these processes are debated resulting in a controversy whether arable land functions as a sink or source for atmospheric co2 global estimations range between a net sink strength of 0 06 1 versus a source of 0 27 1 14 gt c yr 1 for agricultural soils an eco geomorphologic approach which encompasses physical and biological driven factors e g spatio temporal variation in biological geomorphological and biological processes environmental conditions mineralisation and net primary production is of importance to balance the carbon budget and ascertain sink or source formation at landscape scale high spatio temporal variability on process scale imposes constrains to measure and model the fate of soc upon erosion with limited quantitative data available prospective research across the landscape eroding sites transport pathway and depositional sites should include all relevant processes at broad temporal and spatial scales definitive resolution of the sink source controversy lies in further eco geomorphologic research on the fate of soc focussing on long term and spatial extensive monitoring studies combined with advanced measuring modelling and extrapolation techniques to cover broad spatio temporal soc dynamics ascertainment of carbon dynamics in agricultural landscapes provides important insights to balance the carbon budget and finally holds the answer on sink source formation

eolian sediments generated by anthropogenic disturbance of playas human impacts on the geomorphic system and geomorphic impacts on the human system abstract in many of the earth s arid and semiarid lands saline lakes playas and similar landforms are disturbed as a result of human activity diversion and or consumptive use of surface or groundwaters has created the effect of a climate change in numerous drainage basins resulting in the desiccation of lakes and reactivation of eolian processes at many locations playas are natural sites for extensive eolian activity because of the deposition of clastic and chemical sediments in basins by surface water via fluvial transport and groundwater via efflorescence wind erosion and deposition of playa sediments has had a major role in the development of landforms and sedimentary units in the present lunette fields worldwide simpson desert australia and geological past from the triassic mercia mudstone england to the quaternary lahontan basin and cima volcanic field usa anthropogenic disturbance or desiccation of playa systems has resulted in the eolian transport of sand e g lop nor china konya basin turkey rajasthan india kappakoola australia several sites in west africa and or dust e g aral sea kazakhstan uzbekistan old wives lake canada kara bogaz gol ex ussr lake texcoco mexico owens dry lake mono lake and other playas usa typically this is accomplished by abstraction of water and or removal of vegetation from terminal lake basins an extensive review of the literature documents many examples and or potential examples of such phenomena in numerous nations the reactivation of eolian processes from closed basins produces air pollution in the form of fugitive dust naturally occurring compounds released into the atmosphere by human actions and has significant environmental and economic impacts on human activities in the surrounding areas restoration or mitigation of degraded land on or surrounding playas has been accomplished at lake texcoco kara bogaz gol and the konya basin and is being actively implemented at mono lake owens dry lake and the aral sea

technology and geomorphology are improvements in data collection techniques transforming geomorphic science in recent years technological developments have revolutionized our ability to collect data in geomorphology enhanced data collection not only enables us to provide deeper answers to a wider range of fundamental questions about the earth s surface but also encourages us to pose new questions this paper considers in more detail the relationships between science technology and the development of geomorphological tools and techniques reviews the spectrum of tools and techniques now available to geomorphologists and critically assesses what impact new technologies are having on geomorphology it focuses on the role of technology in biogeomorphology and weathering research and how it is advancing theoretical empirical and applied dimensions of these growing sub fields of geomorphology five areas of important technological development are reviewed remote sensing dating geophysical techniques field and laboratory based analysis and sensing of physical and chemical characteristics and field and laboratory based analysis of biological properties there is good evidence that taken together technological developments are revolutionizing geomorphology through opening the doors to better cross scalar investigations blurring the boundaries between laboratory field and computer model and facilitating cross disciplinary and democratized research

the role of evaporites in the genesis of base metal sulphide mineralisation in the northern platform of the pan african damara belt namibia geochemical and fluid inclusion evidence from carbonate wall rock alteration the otavi mountain land is a base metal sulphide ore province in northern namibia where deposits are hosted by platform carbonates of the otavi group in a foreland fold and thrust belt on the northern edge of the pan african damara belt deposits have been classified as the berg aukas or tsumeb types based on differences in ore association stratigraphic position and geochemistry of ores and gangue carbonates mineralisation at these deposits is accompanied by carbonate alteration in the form of dolomite and calcite veins carbonate recrystallisation calcitisation and carbonate silicification based on cathodoluminescence imaging trace and rare earth element ree o and c isotope and fluid inclusion data a series of carbonate generations constituting wall rock alteration around the tsumeb and kombat tsumeb type and berg aukas berg aukas type deposits was established similar data obtained on the recently discovered khusib springs deposit indicate a strong affinity to tsumeb type deposits tsumeb type deposits are distinguished from berg aukas type deposits by having trace element and ree concentrations that are significantly higher in the alteration products compared to the carbonate host rocks only around tsumeb type deposits a relative enrichment in light ree is noted for the hydrothermal carbonate generations that are cogenetic with the main stage of mineralisation microthermometric results from fluid inclusions in carbonate alteration phases and associated quartz indicate relatively high salinity 17 23 wt nacl equivalent for the main mineralising and subsequent sulphide remobilisation stages at the deposits investigated estimated mineralisation temperatures are significantly higher for tsumeb type deposits 370 405 c with early sulphide remobilisation in tsumeb at 275 c whereas they are lower at berg aukas up to 255 c fluid inclusion leachate analysis suggests that most of the observed salinity can be ascribed to dissolved predominantly ca and mg carbonates and chlorides with subordinate nacl na cl br leachate systematics indicate a derivation of the fluid salinity from the interaction with evaporitic rocks en route tsumeb type mineralisation is interpreted to be derived from fluids expelled during pan african orogeny in the more intensely deformed internal zones of the damara belt further south when the high salinity fluids reached the carbonate platform after having scavenged high concentrations of base metals base metal sulphide precipitation occurred in zones of high porosity provided by karst features in the carbonate sequence results obtained for the berg aukas type deposits emphasise their derivation from basinal brines similar to mississippi valley type deposits and confirm that mineralisation of the berg aukas and tsumeb types are both spatially and temporally distinct

holocene aeolian sand mobilization vegetation history and human impact on the stabilized sand dune area of the southern nyirseg hungary abstract almost 20 of the territory of hungary is covered by stabilized dunes formed during the pleistocene with the climate amelioration during the early holocene the aeolian activity ceased however various environmental and anthropogenic factors could have reactivated the aeolian processes today there is an increasing climatic stress on the dune fields of the carpathian basin which is coupled with inadequate land use it is therefore necessary to determine the timing and circumstances of sand mobilization during the holocene the site of the present study is located in a dune interdune system on the southern part of the nyirseg alluvial fan where periods of holocene aeolian activity and environmental change were investigated using palynological and sedimentological methods optically stimulated luminescence and radiocarbon dating the data achieved show climate driven boreal aeolian activity at approximately 8 2 ka and also demonstrate for the first time that during the atlantic phase 6 4 and 5 3 ka in spite of the relatively humid climate and dense vegetation aeolian activity has taken place induced probably by agricultural practices following subboreal morphological stability aeolian activity occurred several times in the subatlantic phase 2 4 2 2 1 2 0 8 and 0 4 0 1 ka as a result of vegetation changes and human activity

variability in fluvial geomorphic response to anthropogenic disturbance abstract humans have greatly impacted the processes and intensities of erosion sediment transport and storage since the introduction of agriculture in many regions around the world accelerated floodplain sedimentation can be related to increases in human pressure on the environment however the relation between the intensity of anthropogenic disturbance and the magnitude of change in fluvial sediment dynamics is not straightforward and often non linear here we review a number of case studies from contrasting environmental settings in the european loess belt the eastern mediterranean mountain ranges and the eastern usa detailed field based sediment archive studies and sediment budgets covering time periods ranging from 200 to over 5000 year as well as the use of pollen and sediment provenance techniques show that no overarching concept of changes in floodplain sedimentation following anthropogenic disturbance can be established slope channel dis connectivity controls the existence of thresholds or tipping points that need to be crossed before significant changes in downstream sediment dynamics are recorded following human impact this coupling can be related to characteristics of human pressure such as its duration intensity and spatial patterns but also to the geomorphic and tectonic setting furthermore internal feedback mechanisms such as those between erosion and soil thickness further complicate the story all these factors controlling the propagation of sediment from eroding hillslopes to river channels vary between regions hence only unique patterns of fluvial geomorphic response can be identified as a result unravelling the human impact from current day sediment archives and predicting the impact of future human disturbances on fluvial sediment dynamics remain a major challenge this has important implications for interpreting contemporary sediment yields as well as downstream sediment records in large floodplains deltas and the marine environment in terms of changes in the drivers of environmental change

the human role in changing fluvial systems retrospect inventory and prospect historical and modern scientific contexts are provided for the 2006 binghamton geomorphology symposium on thehuman role in changing fluvial systems the 2006 symposium provides a synthesis of research concerned with human impacts on fluvial systems including hydrologic and geomorphic changes to watersheds while also commemorating the 50th anniversary of the 1955man s role in changingthe face of the earth symposium thomas jr w l ed 1956a man srole in changing the face of the earth univ chicago press chicago 1193 pp this paper examines the 1955symposium from the perspective of humanimpacts on rivers reviews current inquiry on anthropogenic interactions in fluvial systems and anticipates future directions in this field although the 1955 symposium did not have an explicit geomorphic focus it set the stage for many subsequent anthropogeomorphic studies the 1955 conference provided guidance to geomorphologists by recommending and practicing interdisciplinary scholarship through the use of diverse methodologies applied at extensive temporal and geographical scales and through its insistence on an integrated understanding of human interactions with nature since 1956 research on human impacts to fluvial systems has been influenced by fundamental changes in why the research is done what is studied how river studies are conducted and who does the research rationales for river research are now driven to a greater degree by institutional needs environmental regulations and aquatic restoration new techniques include a host of dating spatial imaging and ground measurement methods that can be coupled with analytical functions and digital models these new methods have led to a greater understanding of channel change variations across multiple temporal and spatial scales and integrated watershed perspectives all changes that are reflected by the papers in this volume these new methods also bring a set of technical demands for the training of geomorphologists the 2006 binghamton geomorphology symposium complements the 1956 symposium by providing a more specific and updated view of river systems coupled with human interactions the symposium focuses on linkages between human land use structures and channel modification with geomorphology hydrology and ecology the emergence of sustainability as a central policy guideline in environmental management should generate greater interest in geomorphic perspectives especially as they pertain to human activities the lack of theories of anthropogeomorphic change however presents a challenge for the next generation of geomorphologists in this rapidly growing subfield

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

late vendian closure of the adamastor ocean timing of tectonic inversion and syn orogenic sedimentation in the gariep basin abstract new pb pb age data obtained on stromatolitic dolomite from the oceanic marmora terrane in the pan african gariep belt support previous ar ar age data on early amphibole that has been related to sea floor metamorphism and indicate formation of oceanic crust in the neoproterozoic adamastor ocean gariep basin around 600 ma a maximum age for oceanic crust in the gariep basin is given by 741 6 ma which is the best available minimum constraint on continental rifting in the gariep belt tectonic inversion to basin closure overlaps in time with the end of a younger glacial period that is recorded both in the oceanic and continental realms and is correlated with the global c 580 ma marinoan glaciation the rock record up to that time in the marmora terrane is completely different to that in the para autochthonous continental port nolloth zone in the east of the belt but the post glacial sediment successions bear many lithological and geochemical similarities these younger successions are therefore interpreted as reflecting syn orogenic deposits in a foredeep the age of which is constrained between c 580 and 550 ma comparison of three chemostratigraphic profiles through the post glacial carbonate succession shows that enrichment in carbonate 13c is in the first instance a function of proximity to the basin margin and thus of the extent of ocean water stratification

aeolian sands and buried soils in the mecklenburg lake district ne germany holocene land use history and pedo geomorphic response abstract the present study is a pedo geomorphic approach to reconstructing holocene aeolian sand dynamics in the mecklenburg lake district ne germany stratigraphical sedimentological and soil research supplemented by morphogenetic interpretations of the genesis of dunes and aeolian sands are discussed a complex late holocene aeolian stratigraphy within a drift sand area was developed at the shore of lake muritz the results were confirmed using palynological records archaeological data and regional history accelerated aeolian activity was triggered by the intensification of settlement and land use activities during the 13th and in the 15th to 16th century ad after a period of stability beginning with population decline during the thirty years war and continuing through the 18th century a final aeolian phase due to the establishment of glassworks was identified during the 19th century ad we assume a direct link between holocene aeolian dynamics and human activities prehistoric holocene drift sands on terrestrial sites have not been documented in the mecklenburg lake district so far this might be explained either by erosion and incorporation of older aeolian sediments during younger aeolian phases and or a lower regional land use intensity in older periods of the holocene the investigated drift sands are stratigraphically and sedimentologically characterised by a high degree of heterogeneity reflecting the spatial and temporal variability of holocene human impact

a model of water and sediment balance as determinants of relative sea level rise in contemporary and future deltas abstract modern deltas are dependent on human mediated freshwater and sediment fluxes changes to these fluxes impact delta biogeophysical functioning and affect the long term sustainability of these landscapes for human and for natural systems here we present contemporary estimates of long term mean sediment balance and relative sea level rise across 46 global deltas we model scenarios of contemporary and future water resource management schemes and hydropower infrastructure in upstream river basins to explore how changing sediment fluxes impact relative sea level rise in delta systems model results show that contemporary sediment fluxes anthropogenic drivers of land subsidence and sea level rise result in delta relative sea level rise rates that average 6 8 mm y assessment of impacts of planned and under construction dams on relative sea level rise rates suggests increases on the order of 1 mm y in deltas with new upstream construction sediment fluxes are estimated to decrease by up to 60 in the danube and 21 in the ganges brahmaputra meghna if all currently planned dams are constructed reduced sediment retention on deltas caused by increased river channelization and management has a larger impact increasing relative sea level rise on average by nearly 2 mm y long term delta sustainability requires a more complete understanding of how geophysical and anthropogenic change impact delta geomorphology local and regional strategies for sustainable delta management that focus on local and regional drivers of change especially groundwater and hydrocarbon extraction and upstream dam construction can be highly impactful even in the context of global climate induced sea level rise

eroding blanket peat catchments global and local implications of upland organic sediment budgets globally peatlands account for circa 50 of terrestrial carbon storage containing as much carbon as is present in the atmosphere the uplands of the uk have an extensive cover of blanket peat but much of it is actively eroding this paper presents a detailed organic sediment budget for a blanket peat catchment in the north pennines and comparative data from a catchment in the southern pennines the catchments have total sediment yields organic and mineral of 44 and 267 t km 2 a 1 and organic sediment yields 31 and 195 t km 2 a 1 respectively they represent two extremes of a spectrum of eroded peat catchments it is demonstrated that the lower sediment yields in the north pennines are associated with extensive natural revegetation of the catchment and consequent reductions in slope channel linkage construction of a carbon budget for the north pennine catchment demonstrates that particulate carbon losses associated with the fluvial suspended sediment load are the largest single carbon loss from the system the system is currently close to carbon neutral but much higher carbon losses associated with actively eroding systems such as the south pennine site would make these systems a major carbon source the possibility that enhanced summer temperatures and winter storminess will accelerate erosion of upland mires means there is a risk that physical degradation of peatlands could become a significant positive feedback on global warming mitigation of these potential global effects will depend on local management informed by a clear understanding of peatland sediment dynamics the sediment budget data here suggest that in gullied peatlands revegetation of gully floors is an effective control on sediment flux so that techniques such as gully blocking are likely to be effective approaches to erosion control

redox sensitive trace element distribution in the loma negra formation in argentina the record of an ediacaran oxygenation event abstract the limestones of the loma negra formation provide an excellent opportunity to examine the behaviour of rare earth elements plus yttrium rey due to the near zero diagenetic alteration of the carbonate system the terrigenous supply to this unit was minimal or scarce in relation to the depth of seawater in which the limestones accumulated the interpreted palaeoenvironment suggests that limestones could have originated by suspension fall out in a shallow open marine ramp the diagenetic features composition and original microtextures are considered good criteria for investigating their rey composition burial diagenesis products were limited and limestones largely preserved their original texture and organic matter as well as their isotope and trace element composition the study of rey distribution in the loma negra formation in different settings of the tandilia system revealed systematic chemostratigraphic patterns related to uniform palaeo redox conditions the general light rare earth element depletion marked positive la y and gd anomalies as well as the clear negative ce anomalies are further features typically ascribed to oxidizing seawater conditions from these results it can be concluded that the loma negra formation documents an oxygenation event that stands out in the overall anoxic ediacaran ocean this record may be correlated with the mid ediacaran oxygenation event ca 580 ma this may support the hypothesis that the clymene ocean was well oxygenated and connected during the ediacaran at least in the southwestern border of gondwana

archaeopedology and chronostratigraphy of colluvial deposits as a proxy for regional land use history baar southwest germany abstract soils are the basis of our food production supplying plants with nutrients and water farming leaves traces in the soil because cultivation can cause soil erosion one result is the formation of colluvial deposits which can be used as geoarchives of past human impacts on their terrestrial environment the present study combines pedological and archaeological knowledge with chronostratigraphic analyses to infer deposition phases of colluvial material thereby allowing the reconstruction of past land use and settlement activities in the baar region sw germany local colluvial signals are interpreted as a regional proxy for increased soil erosion and colluviation on the baar seven main deposition phases of colluvial material can be detected by 28 luminescence dates and 41 radiocarbon ages distributed through 26 soil profiles our results indicate increased colluviation in the younger neolithic 3800 bce the early to middle bronze age 1550 bce the iron age 500 bce the roman empire 100 ce and from the high middle ages onwards 1200 ce 1300 ce 1600 ce these dates and record of colluviation complement archaeological knowledge of the fundamental impact of human activities on the landscape due to sedentism and agriculture early anthropogenic hypothesis our study shows that most periods of intensified colluvial deposition often but not always date to times with colder more humid climatic periods the spatial and temporal correlation of main depositional phases with archaeological finds points to land use as the determining factor of colluvial deposition at least since roman times

isotope stratigraphy of the ediacarian neoproterozoic iii of the adelaide rift complex australia and the overprint of water column stratification abstract this study establishes a high resolution 13c chemostratigraphic framework for the type ediacarian terminal proterozoic section in the adelaide rift complex a framework that contributes to the emerging global chronostratigraphic synthesis of a period that saw momentous changes in the earth s surface environment only 15 m of the 3 5 km thick type section consists of shallow water carbonates of the kind that have formed the basis of most previous studies of neoproterozoic chemostratigraphy however the organic 13corg record reveals a surprising richness of information and shows excellent utility in correlation between sections in the adelaide rift complex lateral variations in 13corg profiles correspond to expected diachronous patterns of basin fill with the addition of 87sr 86sr data correlation can also be made to the officer and amadeus basins consistent with known lithostratigraphic and sequence stratigraphic constraints sublittoral micritic carbonates of the upper nuccaleena formation cap dolostone and lower and middle wonoka formation show strong basinwide 13c depletion 13ccarb 3 to 10 despite compelling evidence for preservation of depositional 13ccarb such as good textural preservation evidence for sea floor lithification and in the wonoka formation pristine 87sr 86sr and low mn sr associated with the depleted carbonates are rare subaqueous evaporite relatively heavy 13corg and anomalously 13c depleted organic carbon of benthic microbial mat origin and a common cause salinity stratification of the water column is postulated the indicated palaeogeographic setting an evaporative mediterranean like basin tenuously connected to the world ocean is entirely consistent with previous suggestions of one or more messinian type desiccation events to explain very deep 1 km incised valleys or canyons in the adelaide rift complex and officer basin at horizons within the wonoka formation and correlates positive excursions in 13corg during basin stratification may in part be due to 12c depletion of surface waters by photosynthetic carbon fixation despite the proposed semi isolation of australian ediacarian basins from the world ocean major 13c excursions which can to some extent be differentiated by the monotonic rise in ediacarian marine 87sr 86sr appear to be correlatable to the upper windermere supergroup northwest canada

a centennial tribute to g k gilbert s hydraulic mining debris in the sierra nevada abstract g k gilbert s 1917 classic monograph hydraulic mining debris in the sierra nevada is described and put into the context of modern geomorphic knowledge the emphasis here is on large scale applied fluvial geomorphology but other key elements e g coastal geomorphology are also briefly covered a brief synopsis outlines key elements of the monograph followed by discussions of highly influential aspects including the integrated watershed perspective the extreme example of anthropogenic sedimentation computation of a quantitative semidistributed sediment budget and advent of sediment wave theory although gilbert did not address concepts of equilibrium and grade in much detail the rivers of the northwestern sierra nevada were highly disrupted and thrown into a condition of nonequilibrium therefore concepts of equilibrium and grade for which gilbert s early work is often cited are discussed gilbert s work is put into the context of complex nonlinear dynamics in geomorphic systems and how these concepts can be used to interpret the nonequilibrium systems described by gilbert broad basin scale studies were common in the period but few were as quantitative and empirically rigorous or employed such a range of methodologies as pp105 none demonstrated such an extreme case of anthropogeomorphic change

high resolution topography for understanding earth surface processes opportunities and challenges abstract in the last decade a range of new remote sensing techniques has led to a dramatic increase in terrain information providing new opportunities for a better understanding of earth surface processes based on geomorphic signatures technologies such as airborne and terrestrial lidar light detection and ranging to obtain high resolution topography have opened avenues for the analysis of landslides hillslope and channellization processes river morphology active tectonics volcanic landforms and anthropogenic signatures on topography this review provides an overview of the recent flourishing literature on high resolution topographic analyses underlining their opportunities and critical issues such as their limitations the goal is to provide answers to questions such as what kind of processes can be analyzed through high resolution topographic data and how to do it the review focuses on two different environments natural and engineered landscapes in both contexts high resolution topography offers opportunities to better understand geomorphic processes from topographic signatures particular attention is given to engineered landscapes in which the direct anthropic alteration of processes is significant the last part of the review discusses future challenges

historical soil erosion by water in germany scales and archives chronology research perspectives abstract the published record of historical soil erosion by water in germany as deduced from dated slope deposits n 306 alluvial sediments n 120 and lake sediments is summarized in this paper the number of sediments investigated reflects the state of knowledge chronology of historical soil erosion and to a certain degree the intensity of the human impact on german landscapes during the holocene even though few data of calculated historical soil erosion intensities exist an estimation of historical soil erosion in germany combining the available data has been calculated soil erosion in germany occurred first locally during the early holocene probably triggered by climatic variability from the neolithic onward the record reflects the human impact according to agricultural land use the observed variability indicates phases of weaker and regained intensity of agricultural land use in germany few records characterise the early and middle bronze age ca 2000 1600 bc and the migration period and the early medieval times ca 400 1000 ad surprisingly for the roman emperor times ca 1 400 ad a decreasing number of soil sediments is recorded even when the data from southern germany is examined separately phases characterised by an increase in soil erosion were the late bronze age and pre roman iron age ca 1600 bc 1 ad the high and late medieval times ca 1000 1350 ad and the modern times ca 1500 ad until today some extraordinary heavy precipitation events late 18th early 19th first half of 14th century pre roman iron age topped the even high soil erosion intensities research gaps as well as potential for future research as derived from the available data are outlined

a novel approach to double spike pb pb dating of carbonate rocks examples from neoproterozoic sequences in southern africa application of the 207 pb 204 pb double spiking technique to correct for mass fractionation led to marked improvement in the quality of pb isotope data and resulting ages obtained on low grade metamorphosed neoproterozoic carbonate rocks from the pan african gariep and saldania belts in southern namibia and south africa carbonate rock powders were dissolved using 1 n acetic acid residue fractions were separated from the supernatant carbonate fractions and analysed separately marbles from the lower pickelhaube formation gariep belt yielded distinctly different 207 pbr 206 pb isochron ages of 728 32 mswds 1 5 and 545 13 ma mswds 7 4 for the carbonate and residue fractions respectively the former is interpreted as dating early diagenesis whereas the latter is in excellent agreement with the timing of regional metamorphism in contrast both the carbonate and residue fractions from the bloeddrif member holgat formation gariep belt and from the kombuis member matjies river formation saldania belt yielded indistinguishable 207 pbr 206 pb isochron ages the isotope data from both fractions combined define an isochron age for the bloeddrif member marbles of

an evolving research agenda for human coastal systems within the broad discourses of environmental change sustainability science and anthropogenic earth surface systems a focused body of work involves the coupled economic and physical dynamics of developed shorelines rapid rates of change in coastal environments from wetlands and deltas to inlets and dune systems help researchers recognize observe and investigate coupling in natural non human morphodynamics and biomorphodynamics this same intrinsic quality of fast paced change also makes developed coastal zones exemplars of observable coupling between physical processes and human activities in many coastal communities beach erosion is a natural hazard with economic costs that coastal management counters through a variety of mitigation strategies including beach replenishment groynes revetments and seawalls as cycles of erosion and mitigation iterate coastline change and economically driven interventions become mutually linked emergent dynamics of two way economic physical coupling is a recent research discovery having established a strong theoretical basis research into coupled human coastal systems has passed its early proof of concept phase this paper frames three major challenges that need resolving in order to advance theoretical and empirical treatments of human coastal systems 1 codifying salient individual and social behaviors of decision making in ways that capture societal actions across a range of scales thus engaging economics social science and policy disciplines 2 quantifying anthropogenic effects on alongshore and cross shore sediment pathways and long term landscape evolution in coastal zones through time including direct measurement of cumulative changes to sediment cells resulting from coastal development and management practices e g construction of buildings and artificial dunes bulldozer removal of overwash after major storms and 3 reciprocal knowledge and data exchange between researchers in coastal morphodynamics and practitioners of coastal management future research into human coastal systems can benefit from decades of interdisciplinary work on the complex dynamics of common pool resources from computational efficiency and new techniques in numerical modeling and from the growing catalog of high resolution geospatial data for natural and developed coastlines around the world

organic walled microfossils and biostratigraphy of the upper port nolloth group namibia implications for latest neoproterozoic glaciations the occurrence of organic walled microfossils is reported for the first time from the neoproterozoic port nolloth group gariep belt southern namibia acritarchs assigned to bavlinella faveolata occur in the hilda subgroup below the younger of two glaciogenic diamictite units numees formation within the port nolloth group the microfossil assemblage in the overlying upper holgat formation above the numees formation is characterized by low diversity six species dominance of soldadophycus bossii and absence of acanthomorphic or large sphaeromorphic acritarchs the agglutinated foraminifer titanotheca also occurs in the holgat formation combined with available chemostratigraphic data and pb pb ages this microfossil assemblage indicates an upper ediacaran age of around 555 ma for the holgat formation virtually identical microfossil assemblages negative to positive 13 c trends 87 sr 86 sr values between 0 7080 and 0 7085 as well as pb pb carbonate ages make it possible to correlate the holgat formation with the buschmannsklippe formation witvlei group central namibia the kombuis member cango caves group southern south africa and the uppermost polanco to lowermost cerro espuelitas formation arroyo del soldado group uruguay based on these data the underlying numees formation the age of which has been only loosely constrained so far and subject to considerable debate can now be assigned to the c 580 ma gaskiers or the possibly younger 13 c excursion and a strong sea level drop if this correlation is confirmed lack of glacial deposits there might have implications for the palaeogeographic extent of upper ediacaran glaciations our preliminary studies show that acritarch biostratigraphy can make a significant contribution to unravelling the stratigraphy of neoproterozoic glacial deposits especially when combined with c and sr isotopic data

late quaternary 15 ka to present development of a sandy landscape in the mol area campine region north east belgium the geomorphological analysis of two sections cut into a sandy landscape in north east belgium enabled the establishment of a chronology for a sequence of events during the last 15 ka that illustrate the polycyclical nature of the evolution of such landscapes field descriptions analytical sediment and soil characterization and pollen analysis are combined with the optically stimulated luminescence dating method to unravel the recent geomorphological history of the investigated site the principal results include apparently discontinuous sand deposition between 15 and 12 ka landscape stabilization and podzol formation between 12 and 1 ka the development of a drift sand landscape between 650 and 200 a and renewed stabilization over the last two centuries the results are discussed in the light of climate land use and vegetation changes and compared with findings at similar sites in the european sand belt

siltation of river influenced coastal environments respective impact of late holocene land use and high frequency climate changes abstract the aim of this study is to unravel the respective influence of land use and high frequency climate changes on the siltation of a river influenced coastal environment an 8 4 m long sediment core was recovered in the pertuis charentais western france an accurate 14 c bayesian age model was developed to perform a depth to time conversion of high resolution sedimentological data obtained on the core forest loss and precipitation changes that occurred on the related catchments were reconstructed from data gathered in the literature a sharp increase in winter rainfall 1700 1750 ad intensified erosion of catchments previously sensitised by increased forest loss 1640 1710 ad which resulted in a massive supply of silt to the coast from ca 1775 ad onwards a review of articles reporting similar mud layers is also proposed depending on their age some major phases of mankind migration history could be traced back which confirms the predominant influence of human activities on the siltation of river influenced coastal environments we therefore propose to group these mud layers into the anthropogenic system tracts in reference to widely used sequence stratigraphy nomenclature and we suggest that it might help to identify a holocene to anthropocene stratigraphic boundary in coastal areas

the human impact in geomorphology 50 years of change abstract concern with the human impact in geomorphology has a long history what is new is that since 1969 a number of developments have taken place that have led to an increasing realisation of its importance these developments are in four main areas i intellectual and policy related ii technological developments that alter geomorphological processes iii demographic trends and iv the proliferation of techniques for the study of landform and process change there has been a realisation of the role of humans in landscape transformation in ancient times the human impact has developed through time but particularly notable are the potential early effects of fire extinctions and deforestation on geomorphological processes the spread of european agriculture particularly in the nineteenth century transformed erosion and sedimentation rates in many parts of the world notwithstanding the importance of some of these changes in prehistoric and historic times recent researches have demonstrated that humans have become an increasingly important agent of geomorphological change during the period of the great acceleration of the past five or six decades the interest in global warming that has developed since the early 1980s has created considerable interest in its consequences for a range of geomorphological phenomena it is also becoming apparent that anthropogenic geomorphological change is having an impact on the earth system as a whole finally geomorphologists have taken an increasing interest in how they can make an impact in the field of landscape conservation

the witputs diamictite in southern namibia and associated rocks constraints for a global glaciation the witputs section of the gariep belt s namibia comprises a sequence of clastic and chemical sediments which have been interpreted as representative of a late neoproterozoic global or near global ice age event and recent biostratigraphic work in the upper rocks of the witputs suggest a late ediacaran age to further characterise this sequence and provide additional age constraints a detailed sedimentological and detrital zircon study has been carried out the petrographic sedimentological and geochemical characteristics of the witputs diamictite determined in this study are homogenous and indicative of debris flow or palaeo valley infill sediments deposited in an oxic environment with no glaciogenic evidence this homogeneity is also reflected in the detrital zircon age spectra with most ages falling between 1 0 and 1 3 ga representing the local geology with the youngest grain at 1030 2 10 9 2 n 92 10 discordance despite the fact that mid and late neoproterozoic volcanic activity is known in the local region the overlying carbonate rocks often considered to be cap carbonates show high mn up to 60 mno with base metal precipitation zn v co and are recrystallised their 13cvpdb isotope ratios are homogeneous at around 3 major and trace element ratios reach values which indicate that c o isotopes may be disturbed and might not reflect primary global seawater composition thus questioning their use for global correlation and comparison with composite chemostratigraphic curves the contact to the overlying late ediacaran sanddrif member is not exposed and the rocks dip in a different direction than the underlying carbonate rocks the c 40 m thick section is characterised by rapid lithology changes including shales calcareous sandstones and wackes fine grained conglomerates and rare clean quartz rich sandstones all of which have strikingly similar detrital zircon populations and the youngest zircon is dated at 1082 8 10 ma 2 errors from 72 grains with 10 discordance acritarchs earlier found in the sanddrif member however indicate a post 570 ma depositional age if the diamictites are glacio marine deposits then an interesting conclusion is that the clastic sediments can display a very immature geochemical signature indicating a localised provenance with derivation purely from the local basement rocks which is also reflected in the detrital zircon populations however we would hesitate to assign a glacial origin to the deposits as no glacial indicators other than a diamictitic texture were observed clearly far more work on the detailed mapping and sedimentology of the neoproterozoic gariep belt deposits is required particularly as many are currently used for global correlation age constraints derived from extensive detrital zircon work can only constrain the deposits as being post 1 03 ma with the detritus being purely locally derived

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

anhydrite and the sr isotope evolution of groundwater in a carbonate aquifer major element concentrations and 87 sr 86 sr ratios were measured in groundwaters and bedrock from the madison aquifer in western south dakota in this region the madison aquifer is primarily comprised of dolomite belonging to the madison limestone group the purpose of the study was to investigate controls on the downgradient evolution of dissolved sr 2 in a carbonate groundwater system that is recharged by waters with high 87 sr 86 sr ratios draining precambrian basement rocks and to establish the sources of sr 2 added to the waters by reaction with the aquifer lithology a mass balance model following previous workers was used to calculate amounts and effective rates of mineral dissolution and precipitation during groundwater transport along a 240 km flow path both the calculated reaction rates and data for the sr isotope geochemistry of the reacting phases were then used to develop a self consistent and quantitative description of the concentration and isotopic composition of dissolved sr 2 in the aquifer waters the major ion chemistry of madison aquifer groundwater is known to evolve according to dolomite dissolution anhydrite dissolution calcite precipitation and ion exchange with clay minerals dissolved 87 sr 86 sr ratios in the madison aquifer decrease downgradient input waters draining the igneous black hills have 87 sr 86 sr ratios of 0 723 while highly evolved waters in the aquifer have 87 sr 86 sr ratios of 0 708 dissolved sr 2 concentrations undergo a concurrent increase from 1200 to 66 000 nmol l model results indicate that dolomite dissolution exerts a critical control on the major ion chemistry but is not the primary source of nonradiogenic sr 2 as both the dissolution rate and sr concentration of dolomite are very low anhydrite is readily soluble in water has a low 87 sr 86 sr ratio 0 708 and a very high sr concentration 50 000 nmol g anhydrite is also greatly undersaturated in the groundwaters and the downgradient evolution of sr 2 accompanies an 80 fold increase in dissolved so 4 2 while anhydrite has a very low abundance in the aquifer rocks the flow model indicates that anhydrite dissolution provides 300 times more sr 2 per liter of water relative to dolomite dissolution these findings suggest that anhydrite dissolution governs the sr 2 geochemistry of madison aquifer groundwaters whereas dolomite dissolution and calcite precipitation control the bulk chemistry lastly it is shown that the calculation of net mineral masses transferred to solution requires very high relative proportions of anhydrite and clay to dolomite mineral masses obtained by this approach actually represent bulk contributions without consideration of the intrinsic reaction rates of the phases or their modal abundances in the aquifer rocks however consideration of these parameters in a transport equation for flow through porous media shows that the high apparent abundances are not a real requirement this latter approach is consistent with laboratory experiments and indicates that as little as 0 04 wt of very soluble anhydrite and 0 3 wt of exchangeable clay in the aquifer rock are sufficient to produce the observed groundwater chemistry in most of the flow path

inundation of a barrier island chandeleur islands louisiana usa during a hurricane observed water level gradients and modeled seaward sand transport large geomorphic changes to barrier islands may occur during inundation when storm surge exceeds island elevation inundation occurs episodically and under energetic conditions that make quantitative observations difficult we measured water levels on both sides of a barrier island in the northern chandeleur islands during inundation by hurricane isaac wind patterns caused the water levels to slope from the bay side to the ocean side for much of the storm modeled geomorphic changes during the storm were very sensitive to the cross island slopes imposed by water level boundary conditions simulations with equal or landward sloping water levels produced the characteristic barrier island storm response of overwash deposits or displaced berms with smoother final topography simulations using the observed seaward sloping water levels produced cross barrier channels and deposits of sand on the ocean side consistent with poststorm observations this sensitivity indicates that accurate water level boundary conditions must be applied on both sides of a barrier to correctly represent the geomorphic response to inundation events more broadly the consequence of seaward transport is that it alters the relationship between storm intensity and volume of landward transport sand transported to the ocean side may move downdrift or aid poststorm recovery by moving onto the beach face or closing recent breaches but it does not contribute to island transgression or appear as an overwash deposit in the back barrier stratigraphic record the high vulnerability of the chandeleur islands allowed us to observe processes that are infrequent but may be important at other barrier islands

geomorphology and forest management in new zealand s erodible steeplands an overview abstract in this paper we outline how geomorphological understanding has underpinned forest management in new zealand s erodible steeplands where it contributes to current forest management and suggest where it will be of value in the future we focus on the highly erodible soft rock hill country of the east coast region of north island but cover other parts of new zealand where appropriate we conclude that forestry will continue to make a significant contribution to new zealand s economy but several issues need to be addressed the most pressing concerns are the incidence of post harvest storm initiated landslides and debris flows arising from steepland forests following timber harvesting there are three areas where geomorphological information and understanding are required to support the forest industry development of an improved national erosion susceptibility classification to support a new national standard for plantation forestry terrain analysis to support improved hazard and risk assessment at detailed operational scales and understanding of post harvest shallow landslide debris flows including their prediction and management

geology of mankind for the past three centuries the effects of humans on the global environment have escalated because of these anthro pogenic emissions of carbon dioxide global climate may depart significantly from natural behaviour for many millennia to come it seems appropriate to assign the term anthropocene to the present in many ways human dominated geological epoch supplementing the holocene the warm period of the past 10 12 millennia

geomorphic and human influence on large scale coastal change abstract an increasing need exists for regional scale measurements of shoreline change to aid in management and planning decisions over a broad portion of the coast and to inform assessments of coastal vulnerabilities and hazards a recent dataset of regional shoreline change covering a large portion of the u s east coast new england and mid atlantic provides rates of shoreline change over historical 150 years and recent 25 30 years time periods making it ideal for a broad assessment of the regional variation of shoreline change and the natural and human induced influences on coastal behavior the variable coastal landforms of the region provide an opportunity to investigate how specific geomorphic landforms relate to the spatial variability of shoreline change in addition to natural influences on the rates of change we examine the effects that development and human modifications to the coastline have on the measurements of regional shoreline change regional variation in the rates of shoreline change is a function of the dominant type and distribution of coastal landform as well as the relative amount of human development our results indicate that geomorphology has measurable influence on shoreline change rates anthropogenic impacts are found to be greater along the more densely developed and modified portion of the coast where jetties at engineered inlets impound large volumes of sediment resulting in extreme but discrete progradation updrift of jetties this produces a shift in averaged values of rates that may mask the natural long term record additionally a strong correlation is found to exist between rates of shoreline change and relative level of human development using a geomorphic characterization of the types of coastal landform as a guide for expected relative rates of change we found that the shoreline appears to be changing naturally only along sparsely developed coasts even modest amounts of development influence the rates of change and the human imprint override the geomorphic signal the study demonstrates that human activities associated with creating and maintaining coastal infrastructure alter the natural behavior of the coast over hundreds of kilometers and time spans greater than a century this suggests that future assessments of vulnerability based largely on rates of change along developed coastlines need to take the role of human alterations into account

ancient maya impacts on the earth s surface an early anthropocene analog abstract the measure of the mayacene a microcosm of the early anthropocene that occurred from c 3000 to 1000 bp comes from multiple late quaternary paleoenvironmental records we synthesized the evidence for maya impacts on climate vegetation hydrology and the lithosphere from studies of soils lakes floodplains wetlands and other ecosystems maya civilization had likely altered local to regional ecosystems and hydrology by the preclassic period 3000 1700 bp but these impacts waned by 1000 bp they altered ecosystems with vast urban and rural infrastructure that included thousands of reservoirs wetland fields and canals terraces field ridges and temples although there is abundant evidence that indicates the maya altered their forests even at the large urban complex of tikal as much as 40 of the forest remained intact through the classic period existing forests are still influenced by ancient maya forest gardening particularly by the large expanses of ancient stone structures terraces and wetland fields that form their substrates a few studies suggest deforestation and other land uses probably also warmed and dried regional climate by the classic period 1700 1100 bp a much larger body of research documents the maya impacts on hydrology in the form of dams reservoirs canals eroded soils and urban design for runoff another metric of the mayacene are paleosols which contain chemical evidence for human occupation revealed by high phosphorus concentrations and carbon isotope ratios of c 4 species like maize in the c 3 dominated tropical forest ecosystem paleosol sequences exhibit maya clays a facies that reflects a glut of rapidly eroded sediments that overlie pre maya paleosols this stratigraphy is conspicuous in many dated soil profiles and marks the large scale maya transformation of the landscape in the preclassic and classic periods some of these also have increased phosphorous and carbon isotope evidence of c 4 species we synthesize and provide new evidence of maya period soil strata that show elevated carbon isotope ratios 13 c indicating the presence of c 4 species in typical agricultural sites this is often the case in ancient maya wetland systems which also have abundant evidence for the presence of several other economic plant species the mayacene of c 3000 to 1000 bp was thus a patchwork of cities villages roads urban heat islands intensive and extensive farmsteads forests and orchards today forests and wetlands cover much of the maya area but like so many places these are now under the onslaught of the deforestation draining and plowing of the present anthropocene

man s footprint on the arctic environment as revealed by analysis of ice and snow abstract the date of the definitive start to the anthropocene is still under debate and although a lot of progress has been made currently available data is not precise enough to define the start of the human dominated geological epoch we know that during and after the industrial revolution humans started having a much greater impact on the earth s environment increases in population have led to increases in resource and fossil fuel use leaving a marked impact on our planet this impact in the northern hemisphere is effectively recorded in the snow and ice of the arctic human activity has changed various biogeochemical cycles to such an extent that the climate has started to change this has disturbed the biosphere pushing it to adapt in response to these changes through evolutionary pressure the arctic is a particularly vulnerable environment and mankind is having a profound impact on its fragile equilibrium higher concentrations of heavy metals organic compounds and radionuclides have been detected in ice cores as well as snow although climatic changes are evident on a global scale in the arctic these changes have been amplified advances in laboratory analysis methods have been applied to ice cores and surface snow samples to help us understand the mechanisms governing this fragile environment and to evaluate the impact and amplitude of human activity despite these advances the fluxes and distributions over time of anthropogenic organic compounds is largely unknown hopefully advances in analytical methods will mean that this is not the case in the future

geomorphology complexity and the emerging science of the earth s surface the following is a white paper adapted here for print for the u s national research council s committee on challenges and opportunities in earth surface processes drafted at a national science foundation sponsored workshop associated with the 38th binghamton geomorphology symposium complexity in geomorphology held at duke university in october 2007

geology of the skorpion supergene zinc deposit southern namibia the skorpion zinc deposit in southwestern namibia comprises a significant nonsulfide orebody 24 6 mt at 10 6 zn and subordinate amounts of primary base metal sulfide mineralization which structurally underlies the nonsulfide ores at depth the host rocks of the blind nonsulfide orebody and relict sulfide mineralization consist of a mixed volcano sedimentary sequence of neoproterozoic age that has formed in an initial continental rift system between the kalahari cratonic province and the rio de la plata cratonic province the metavolcanic and subvolcanic rocks display a distinct bimodal geochemical composition of within plate affinity and have been emplaced under an extensional crustal regime zircons from a rhyolitic vesicular flow extruded approximately contemporaneously with the volcanic hosted sulfide mineralization have been dated by shrimp u pb analysis and yield an age of 751 9 5 5 ma the basin that hosts the skorpion deposit has been shaped by horst and half graben tectonics which also controlled the sedimentary deposition of siliciclastic and carbonate sediments within both shallow and deeper water environments the rock sequence was affected by a major tectono metamorphic event the pan african brasiliano orogeny at approximately 550 to 545 ma metamorphism reached uppermost greenschist to lowermost amphibolite facies and the complex deformational style of the region is the result of intense faulting folding and thrusting the skorpion orebody is hosted by arkosic metaarenites and subordinately by volcaniclastic metasedimentary rocks it is irregularly shaped transgressive to sedimentary layering and has a relatively flat top which is covered by a blanket of unmineralized overburden consisting of calcrete boulder beds and recent sand dunes at depth the orebody has a relatively sharp contact with a barren marble unit on the east and south and a more gradational boundary within the siliciclastic host rocks on the west and north the nonsulfide ore minerals comprise predominantly sauconite zn smectite substantial amounts of hemimorphite and smithsonite and subordinate amounts of scholzite tarbuttite atacamite hydrozincite and hetearolite the ore minerals are mainly euhedral and subhedral crystals and occur as open space fillings in intergranular voids fractures and breccias and as replacements of feldspar and mica the metasedimentary host rocks of the nonsulfide ore contain abundant iron hydroxide pseudomorphs after disseminated sulfides and stringers and after rare semimassive stratiform layers of sulfides gossanous manganese and iron hydroxide rich siliciclastic metasedimentary rocks are common in the western and northwestern vicinity of the nonsulfide orebody alteration of the supergene mineralized host rocks includes removal of calcite cement and the breakdown of detrital albite rich plagioclase and of minor orthoclase local alteration phenomena also include silicification and rare secondary barite both a result of the alteration and breakdown of feldspar minor base metal sulfide mineral deposits occur in metarhyolitic flows and felsic hyaloclastic rocks structurally below the nonsulfide orebody the primary sulfide minerals comprise pyrite pyrrhotite sphalerite minor chalcopyrite and galena as well as secondary chalcocite and colloidal sphalerite brunckite the volcanic hosted sulfide ore minerals are deformed and partly recrystallized and thus of premetamorphic and predeformation origin in contrast the skorpion nonsulfide zinc deposit is of postmetamorphic origin as shown by two hydrous low p low t ore assemblages the secondary assemblages occur at least partly as delicate euhedral and subhedral crystals in secondary pore space open fractures veins and breccias the nonsulfide ore contains pseudomorphs from in situ oxidation and replacement of preexisting sulfides and ore and also from the remobilization or precipitation of base metals the skorpion nonsulfide zinc deposit is of supergene origin and formed from the oxidation of sulfide protore by circulating meteoric water as suggested by textural evidence and by initial stable isotope data the timing of ore formation is still undefined but lies within the large age bracket between 545 ma peak metamorphism and subsequent partial exhumation and the deposition of the nonmineralized overburden of namib desert gravels 21 ma and dune sands

the history of soil erosion and fluvial deposits in small catchments of central europe deciphering the long term interaction between humans and the environment a review abstract during the last few decades many case studies focused on the dynamics of fluvial systems in response to hillslope erosion land use impact and climate changes this paper will review the current state of knowledge of the dynamics of past soil erosion and gullying in small catchments

the holocene 15 8 2005 pp 1227 1235 a geoarchaeological chronology of holocene dune building on san miguel island california a data base of 114 14c dates from 40 archaeological sites in san miguel island sand dunes provides a general chronology for holocene dune building although rising seas have probably submerged earlier evidence postglacial dune building on san miguel began as early as 10000 years ago more intensive dune building dates to the middle and late holocene including large parabolic dunes that traverse the island and climb some of the highest landforms native american peoples lived on and altered island sand dunes for nearly 10 000 years and native burning and other landscape alterations may have contributed to periodic destabilization of island dunefields accumulation of cultural debris also facilitated anthropogenic soil formation in many coastal localities however and over the millennia midden debris protected large expanses of the island s coastal perimeter from wind erosion with the introduction of sheep c ad 1850 destabilization and erosion of dune soils caused by overgrazing and other human impac

combining geomorphometry feature extraction techniques and earth surface processes research the way forward abstract in recent years the wealth of technological development revolutionised our ability to collect data in geosciences due to the unprecedented level of detail of these datasets geomorphologists are facing new challenges giving more in depth answers to a broad er range of fundamental questions across the full spectrum of the earth s and planetary processes this contribution builds on the existing literature of geomorphometry the science of quantitative land surface analysis and feature extraction translate land surface parameters into extents of geomorphological elements it provides evidence of critical themes as well as emerging fields of future research in the digital realm supporting the likely effectiveness of geomorphometry and feature extractions as they are advancing the theoretical empirical and applied dimension of geomorphology the review further discusses the role of geomorphometric legacies and scientific reproducibility and how they can be implemented in the hope that this will facilitate action towards improving the transparency and efficiency of scientific research and accelerate discoveries in geomorphology in the current landscape substantial changes in landforms ecosystems land use hydrological routing and direct anthropogenic modifications impact systems across the full spectrum of geomorphological processes although uncertainties in the precise nature and likelihood of changes exist geomorphometry and feature extraction can aid exploring process regimes and landscape responses taken together they can revolutionise geomorphology by opening the doors to improved investigations crossing space and time scales blurring the boundaries between traditional approaches and computer modelling and facilitating cross disciplinary research ultimately the exploitation of the available wealth of digital information can help to translate our understanding of geomorphic processes which is often based on observations of past or current conditions into the rapidly changing future

the nama foreland basin sedimentation major unconformity bounded sequences and multisided active margin advance abstract the nama foreland basin developed in neoproterozoic times as a peripheral foreland basin between the kalahari craton in the east and the partly contemporaneous damara and gariep orogenic belts in the north and west the foreland basin is subdivided into three basins from north to south the zaris witputs and vanrhynsdorp basins deposits of the nama group proper fill the first two basins whereas the third contains the vanrhynsdorp group which differs in many aspects from the nama group only during its latest phase of development did the foreland basin form one continuous depository the stratigraphic sequences in all three basins are suggested to be genetically related to orogenesis flexural bulging and sea level changes that affected the basin throughout its history palaeocurrent studies show that clastic sediments were initially derived from the craton and transported west and southwestwards in fluvial environments along the entire length of the basin as mountain belts emerged along the interactive northern and western orogenic margins transport directions switched to southerly and southeasterly foredeep flysch and ramp carbonates grade upwards into reddish conglomeratic molasse derived entirely from these orogens three major unconformity bounded sequences composite sequences probably of second order cyclicity can be recognised the uppermost composite sequence cs3 comprises the fish river subgroup whereas the lower composite sequence cs1 is composed of the flaminkberg formation and the kwanous kuibis and lower and middle schwarzrand subgroups cs2 comprises the knersvlakte brandkop and upper schwarzrand subgroups cs1 is composed of transgressive and highstand sequence sets onlapping the craton and truncated by a type 1 unconformity at the base of the nomtsas formation cs2 contains a conformable lowstand flysch delta partly derived from cs1 deposits eroded on flexural bulges as well as an orogenic source in the northwest cs3 is entirely composed of orogen derived molasse onlapping a basal type 2 unconformity and overstepping older sequences in a cratonward direction a number of intrabasinal unconformities is ascribed to flexural bulging in response to tectonic and sedimentary loading the age of the nama and vanrhynsdorp groups is estimated at between 600 ma and 530 ma as determined by the age of the basement the age of detrital micas and the age of subsequent thrust and fold tectonic events that vary in vergence from southeast to northeast which affected nama and vanrhynsdorp rocks along the active basin margins marginal tectonogenesis of the nama foreland basin resulted from northwesterly subduction of the kalahari plate underneath the congo and south american plates through a process of sinistral transpression along the western kalahari margin leading to sequential closure of the proto atlantic adamastor ocean from north to south

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

long term non local coastline responses to local shoreline stabilization 1 the future of large scale coastline evolution will be strongly coupled to human manipulations designed to prevent erosion we explore the consequences of this coupling using a numerical model for large scale coastline evolution to compare the long term non local effects of two generalized classes of shoreline stabilization 1 beach nourishment the addition of dredged sand to an eroding beach and 2 hard structures e g seawalls groynes etc which fix the position of the shoreline without adding sand in centurial model experiments where localized stabilization is maintained in the context of changing climate forcing both forms of stabilization are found to significantly alter patterns of erosion and accretion at distances up to tens of kilometers on a cuspate cape coastline similar to the north and south carolina coast usa with stabilization applied to the eroding updrift flank of a single cape perturbations to coastline evolution are qualitatively similar within 20 km for each stabilization scenario though they differ in magnitude both updrift and downdrift of the stabilized shoreline the human signal in coastline change can extend as far as a neighboring cape approximately 100 km away but these long range effects differ for each scenario nourishment resulted in seaward growth of the stabilized cape increasing the extent that it blocked sediment flux in downdrift regions of the coast through wave shadowing when stabilized with a hard structure the cape s initial position remain fixed decreasing wave shadowing

biotic response to explosive volcanism ostracod recovery after ordovician ash falls abstract the impact of two ordovician ash falls of different intensities was studied in order to determine the recovery patterns of benthic ostracods the studied sections are of sandbian age in nw estonia at poosaspea the kinnekulle k bentonite 40 cm derived from a major volcanic event and at ristna the grimstorp bentonite 6 cm in poosaspea important faunal changes are observed the three pre crisis dominant species i e tetrada memorabilis steusloffina sp nov and olbianella braderupensis were not recovered above the bentonite and at least two of them became extinct the post crisis ecosystem shows strong perturbations of diversity and abundance for a long period of time in ristna the impact of the ash fall is less dramatic all of the dominant pre crisis species survived although some changes in abundance and diversity are observed these results show that significant ash falls lead to marked rearrangement of assemblages and extinction of some taxa while less prominent volcanic episodes only result in temporary changes in the assemblage structure in both cases recovery follows several steps post event ecosystem with survival faunas very low abundance low diversity one two species opportunistic taxa e g sigmoopsis rostrata circulinella nuda dominate the assemblage early stages of recolonization with recovery faunas increasing abundance and diversity recolonization by pre event and immigrant species after a short disturbance period return to climax assemblages with specialized taxa high abundance high diversity although assemblages recovered rapidly after the crises the recovery periods still seem much longer than observed in recent foraminiferal assemblages causal links between the volcanic events and subsequent diversifications could not be demonstrated

a connection between the neoproterozoic dom feliciano brazil uruguay and gariep namibia south africa orogenic belts evidence from a reconnaissance provenance study abstract a provenance study of neoproterozoic siliciclastic successions in the stratigraphically and tectonically lowermost and uppermost parts of the pan african gariep belt stinkfontein subgroup and oranjemund group respectively in southwestern africa as well as in the rocha group of the punta del este terrane dom feliciano belt in uruguay revealed that the oranjemund and rocha groups can be correlated and most likely formed in the same basin thus the rocha group is considered to represent the fill of the westernmost part of a re activated ediacaran gariep basin the lower parts of the oranjemund and rocha groups reflect erosion of mafic rocks whereas the upper parts are derived from a predominantly felsic source area first major and trace element geochemical data are consistent with oceanic islands of within plate geochemistry in the immediate vicinity as the most likely source of the mafic input into the lower part of the oranjemund group whereas a combination of continental margin and island arc is indicated as source for the bulk of the younger sediments in the upper oranjemund group age spectra obtained by shrimp u pb analyses of detrital zircon grains from the stinkfontein subgroup port nolloth group the oranjemund group and the rocha group are very similar except for a lack of the youngest age group around 600 ma in the stinkfontein subgroup in all three units zircon grains of 1000 1200 ma dominate with a further peak in the age distribution between 1700 and 2000 ma these ages compare well with the pre gariep basement geology in southwestern africa where the former age range corresponds to magmatic and high grade metamorphic activity in the mesoproterozoic namaqua natal belt and the latter to an extensive palaeoproterozoic andean type volcanic arc richtersveld terrane comparable ages are conspicuously absent in the basement of the rio de la plata craton in south america derivation of the rocha group sediments from a similar source as the contemporaneous oranjemund group sediments is therefore suggested the most likely source of the youngest detrital zircon grains in these two stratigraphic units is the 640 590 ma magmatic arc of the dom feliciano belt this interpretation explains the continental island arc component in the sediment provenance and takes into account the absence of comparable magmatism in the gariep belt two stages of basin evolution are distinguished for the gariep basin an early failed continental rift that subsequently became re activated as back arc basin related to the cryogenian dom feliciano arc consequently the gariep basin does not represent the main suture between the rio de la plata and the kalahari cratons this suture is now suspected to be west of the dom feliciano volcanic arc and might be connected with the sierra ballena major gercino lineament

the anthropic landscape imprint around one of the largest roman hydraulic gold mines in europe sierra del teleno nw spain abstract this study explores the information gathered from the landscape transformation that occurred during the intense period of roman hydraulic gold mining activity in northwest spain the sierra del teleno and its surroundings are characterised by the presence of quaternary glacial and periglacial deposits and locally neogene alluvial sediments which were intensely mined by the romans however the mining debris often obscures natural deposits making their identification and description a challenging task the aim of this study is to determine the existence of specific geomorphological features that can improve the identification of anthropic elements related to mining activity river captures and widened drainage systems are among the most outstanding structures remaining due to the extent and complexity of the work involved however other mining elements such as anthropic modification of alluvial fans moraine deposits and rock ridges are also evident in the landscape in many cases these remains are linked to the hydrologic infrastructure found in the area which mainly comprises an extensive system of natural and man made channels and distribution water tanks difficulties arise in areas where no such structures are found thus the use of geomorphic elements and patterns can help to distinguish natural and anthropic landforms using this approach therefore we have performed the first systematic and detailed analysis of the morphological imprint of roman hydraulic gold mining activity on the landscape these data will help piece together the puzzle of how the landscape was transformed by roman mining activity and can contribute to discussions surrounding the new epoch the anthropocene