the influence of surface and tectonic processes on landscape evolution of the iberian chain spain quantitative geomorphological analysis and geochronology abstract in tectonically active areas the landscape response to tectonic forcing is described and possibly quantified by regional topographic and hydrographic features as well as by spatial variation in rates of surface processes we investigated the recent landscape evolution of the iberian chain ne spain an intraplate thrust belt formed in cenozoic times and characterized by a dome shaped topography in its central sector the landscape is dominated by low relief surfaces late neogene in age presently standing at an average altitude of 1300 m a recent regional uplift controlled the organization of the present fluvial network and dissection of the landscape in this framework we investigated the geomorphic responses to tectonic forcing by the calculation of morphometric parameters focusing on topography map of local relief swath profiles and hydrography basin hypsometric curve and integral basin asymmetry factor river longitudinal profiles and relative indices and using srtm dem the results of morphometric analysis have been coupled with radiometric uranium series dating of calcareous tufas lying on fluvial strath terraces the obtained ages allow the estimation of incision rate along the high tajo and martin rivers our results indicate that uplift and rock type erodibility are the main factors influencing landscape evolution of the study area the incision rates are very similar throughout the central sector of the range indicating that despite subtle local variation the rivers are responding to a main tectonic input the regional uplift in conclusion the iberian chain landscape is in a transient state in response to a recent dome like uplift indeed the fluvial processes that weakly incised this landscape at a rate of 0 6 mm yr are approaching a radial pattern on the basis of geological and geomorphic constraints we hypothesize that the uplift started around or after 3 ma

drainage network dynamics and knickpoint evolution in the ebro and duero basins from endorheism to exorheism abstract the study of fluvial network rearrangement provides a key to understand past and future landscape evolution large perturbations of hydrographic basins such as the change from endorheism to exorheism have repercussions in the steady or disequilibrium state of the basins and their drainage divides such transitions from internal to external drainage imply a major lowering of the geomorphological base level causing a major retreating knickpoint wave that separates the upstream low relief area inherited from the endorheic period from the downstream incised area subsequently the water divide migrates to reach an equilibrium in which erosion rates at both sides of the divide are similar previous fluvial analyses suggest that both the duero and ebro drainage networks the two largest catchments in iberia experienced a change from endorheism to exorheism sometime between the late miocene and the pliocene fluvial capture evidence argues for a pliocene westward migration of the ebro duero divide implying an area decrease for the duero fluvial network victim in favor of the ebro aggressor we used river profiles knickpoint distribution and chi map calculation to understand the different degree of erosion of the duero and the ebro catchments and the dynamics of their drainage network the results show an equilibrated ebro drainage network in contrast with a disequilibrium in the erosional state of the duero drainage which remains reorganizing and adapting to the newly imposed atlantic base level we identified at least two knickpoint wave trains in the duero drainage resulting from the onset of exorheism a fast propagating wave through the cover and a low propagating wave affecting the bedrock field evidence and topographic analysis suggest a westward migration of the ebro duero divide resulting in an ongoing headward erosion of the ebro against the duero catchment chi analysis provides the degree of disequilibrium of the drainage network indicating a large scale aggressor role for the duero and a victim role for the ebro we interpreted this seeming contradiction as the result of a different time scale perspective local divide observations indicate a victim duero in the short term whereas basin scale dynamics support a victim role for the ebro fluvial network in the long term multi million year time scales

a gis method to identify flat surfaces and restore relict fluvial long profiles from terrace remnants gives new clues on how large basins respond to endorheic exorheic transitions duero basin iberian peninsula this is an mite contribution spanish government plan estatal de investigacion cientifica y tecnica y de innovacion cgl2014 59516 pr2011 0044 gis technical support was funded by the spanish ministerio de economia y competitividad under grant pej 2014 a 93258 lrr is funded by the marie curie clarin cofund programme reference aca 17 19 ficyt principality of asturias

revealing the pace of river landscape evolution during the quaternary recent developments in numerical dating methods during the last twenty years several technical developments have considerably intensified the use of numerical dating methods for the quaternary the study of fluvial archives has greatly benefited from these enhancements opening new dating horizons for a range of archives at distinct time scales and thereby providing new insights into previously unanswered questions in this contribution we separately present the state of the art of five numerical dating methods that are frequently used in the fluvial context radiocarbon luminescence electron spin resonance esr 230th u and terrestrial cosmogenic nuclides tcn dating we focus on the major recent developments for each technique that are most relevant for new dating applications in diverse fluvial environments and on explaining these for non specialists therefore essential information and precautions about sampling strategies in the field and or laboratory procedures are provided for each method new and important implications for chronological reconstructions of quaternary fluvial landscapes are discussed and where necessary exemplified by key case studies a clear statement of the current technical limitations of these methods is included and forthcoming developments which might possibly open new horizons for dating fluvial archives in the near future are summarised

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

using river long profiles and geomorphic indices to evaluate the geomorphological signature of continental scale drainage capture duero basin nw iberia well constrained case studies of transient landscape responses are needed to improve our understanding of erosion processes associated with drainage captures the duero basin is an excellent location for such a study because the landscape is currently undergoing pronounced geomorphological changes resulting from the opening of a former closed drainage the present day continental interior basin n50 000 km2 drains to the atlantic ocean via the duero river but during the cenozoic the basin experienced a long endorheic period marked by the formation of evaporites currently the entire continental interior is an area of relative tectonic quiescence characterised by a relict low relief upland topography meseta systematic variations in lithology and a well constrained tectonic setting throughout the basin and adjacent areas allow for the comparison of channel morphology between the cenozoic duero basin and its western fringe to explore the signal of transient geomorphic response to capture and opening of the former endorheic basin the main channel and 24 tributaries were analysed in terms of their longitudinal profiles and the application of geomorphic indices concavity index ci valley floorwidth to height ratio vf and stream length gradient index sl the analysis reveals two zones with distinctive morphologies 1 an upper reach domain consisting of broad flat valleys and low gradient streams where concave longitudinal profiles dominate and 2 a middle reach domain characterised by steep deeply incised canyons where a convex long profile dominates marking a major kinckzone the quantitative information on channel shapes and long profile geometries allows the interpretation of these patterns in terms of driving forces for fluvial landscape development large scale morphometric analysis highlights the transient response of the entire basin to a capture related base level lowering and illustrates the importance of drainage captures as potential internal drivers of landscape modification and topographic adjustments furthermore the duero basin case study also emphasises that well constrained bedrock geology and tectonic patterns are essential to avoid misinterpretation of geomorphic indexes

coastal tectonics on the eastern margin of the pacific rim late quaternary sea level history and uplift rates channel islands national park california usa abstract the pacific rim is a region where tectonic processes play a significant role in coastal landscape evolution coastal california on the eastern margin of the pacific rim is very active tectonically and geomorphic expressions of this include uplifted marine terraces there have been however conflicting estimates of the rate of late quaternary uplift of marine terraces in coastal california particularly for the northern channel islands in the present study the terraces on san miguel island and santa rosa island were mapped and new age estimates were generated using uranium series dating of fossil corals and amino acid geochronology of fossil mollusks results indicate that the 2nd terrace on both islands is 120 ka and the 1st terrace on santa rosa island is 80 ka these ages correspond to two global high sea stands of the last interglacial complex marine isotope stages mis 5 5 and 5 1 respectively the age estimates indicate that san miguel island and santa rosa island have been tectonically uplifted at rates of 0 12 0 20 m ka in the late quaternary similar to uplift rates inferred from previous studies on neighboring santa cruz island the newly estimated uplift rates for the northern channel islands are however an order of magnitude lower than a recent study that generated uplift rates from an offshore terrace dating to the last glacial period the differences between the estimated uplift rates in the present study and the offshore study are explained by the magnitude of glacial isostatic adjustment gia effects that were not known at the time of the earlier study set in the larger context of northeastern pacific rim tectonics channel islands uplift rates are higher than those coastal localities on the margin of the east pacific rise spreading center but slightly lower than those of most localities adjacent to the cascadia subduction zone the uplift rates reported here for the northern channel islands are similar to those reported for most other localities where strike slip tectonics are dominant but lower than localities where restraining bends such as the big bend of the san andreas fault result in crustal shortening

a sheetflow sediment transport model for skewed asymmetric waves combined with strong opposite currents abstract prototype scale physical model tests were conducted to investigate the sheetflow sediment transport of uniform sand under different skewed asymmetric oscillatory flows with and without the presence of relatively strong currents in the opposite direction against wave propagation experiments show that in most cases with fine sands the cancelling effect which balances the on off shore net transport under pure asymmetric skewed oscillatory flows and results a moderate net transport was developed for combined skewed asymmetric shaped oscillations however under certain conditions t 5 s with coarse sands the onshore sediment transport was enhanced for combined skewed asymmetric flows additionally the new experimental data under collinear oscillatory flows and strong currents show that offshore net transport rates increase with decreasing velocity skewness and acceleration skewness sediment movement behaviors were investigated through analysis of experimental data obtained from the image analysis technique and attempts were made to estimate and formulate the sheetflow layer thickness accordingly sediment transport under oscillatory sheetflow conditions was studied and successfully explained by comparing the bed shear stress and the phase lag parameter at each half cycle consequently these parameters were incorporated in an improved dibajinia and watanabe s type sediment transport model the formula is calibrated against a comprehensive experimental data 331 in total good agreement obtained between predictions and measurements shows that the new formula is fulfilled for practical purposes

an automated method to extract fluvial terraces from digital elevation models the vesdre valley a case study in eastern belgium abstract fluvial terraces are a powerful tool for unraveling the combined tectonic and climatic conditions that controlled directly or indirectly the quaternary incision of rivers terrace long profiles are usually retrieved from sparse traces of ancient floodplains preserved in the present topography however when these traces classically collected from topographic maps aerial photographs and field analyses are too few the inferred profiles may be questionable yet the now available high quality and high resolution digital elevation models dems offer an opportunity to increase greatly the quantity of information usable to reconstruct terrace profiles therefore the purpose of this study was to develop a new dem based method of terrace recognition in order to create a larger database and better constrain the profile reconstruction moreover particular procedures of image and numerical processing were defined to fully automate the analysis basically our method relies on the production of bivariate scatter plots depicting the relation between slope and relative altitude i e the altitude above the current alluvial plain for all pixels of successive sections of the valley for each scatter plot the curve of the lowest slope values observed at every relative altitude is smoothed and its minima are assumed to locate the altitudes of the terrace elements preserved in the section we successfully tested this method in the vesdre valley incised in the ne ardenne massif e belgium notably identifying fault deformation of the profiles the main advantages of our approach are its objectivity exhaustiveness and rapidity allowing fast and coherent analysis of many rivers over extended regions

modeling tropical convergence based on the moist static energy budget abstract the vertically integrated moist static energy equation provides a convenient starting point for the construction of simple models of the time mean low level convergence in the tropics a vertically integrated measure of the moist static stability the gross moist stability proves to be of central importance minima in this quantity mark the positions of the tropical convergence zones we argue that the positions of these minima are determined by the time mean moisture field which is in turn closely tied to the time mean surface temperature

the madrid basin and the central system a tectonostratigraphic analysis from 2d seismic lines abstract data from deep boreholes seismic surveys and surface geology are used to reconstruct the sedimentary infilling of the cenozoic madrid basin eight main depositional sequences and seismic units are recognised from the paleogene the latter four of these sedimentary sequences were deposited in a continental environment under the influence of tectonic activity in the central system the toledo mountains the iberian chain and the sierra de altomira the sedimentary infill shows an overall coarsening upward trend from upper cretaceous formations to syn tectonic conglomerate deposits followed by a fining upward sequence and moderate reactivation of some faults during the late miocene pliocene the syn tectonic sediments are oligocene early miocene in age the foredeep is oriented northeast southwest and shows a sediment thickness of up to 3800 m in areas close to the central system several types of tectonic structures are recognised including imbricate thrust systems thrust triangle zones fault propagation folds back thrust systems and pop up structures the frontal thrusts were subjected to significant erosion and late miocene sediments onlap the anticlines of the onshore foreland nw se trending positive flower structures have been recognised in the eastern part of the basin the total northwest southeast shortening across the contact between the madrid basin and the central system is approximately 5 km of which 2 3 km occurred across the southern border thrust the simultaneous basement uplift of the central system and the tectonic escape of the sierra de altomira have been interpreted as a consequence of constrictive deformation within the pyrenean foreland of the iberian microplate

initiation of an active margin at the north iberian continent ocean transition 1 the north iberian or cantabrian margin located at the southern flank of the bay of biscay underwent successive tectonic regimes of rifting passive margin and compression from mesozoic to tertiary times a complete crustal cross section of the north iberian margin from the abyssal plain to the shoreline and a reconstruction of its undeformed upper cretaceous structure are presented here it is constrained after the compilation and interpretation of different geophysical data sets recently available in the area the reflective pattern is provided by deep seismic reflection profile escin 4 complemented by commercial profiles and well information from the north iberian platform and the velocity depth control comes from an onshore offshore wide angle seismic profile tested also with gravity modeling the detailed cross section of the meso tertiary basins that fill the platform and abyssal plain shows structures from the three main tectonic events 1 normal faults and asymmetric basins from the permian to lower cretaceous extensional stage 2 upper cretaceous sediments deposited under stable conditions during the passive margin period and 3 inverted faults thrusts and folds related to the tertiary compression the deep structure of the crust beneath the margin is poorly constrained from escin 4 profile that shows reflectivity in the lower crust only at a small area under the platform however the corresponding wide angle experiment provides a conspicuous image of the moho that shows a continued deepening toward the continent on the basis of the geophysical results we propose a new model for this margin where the lower crust is detached and underthrusted to the south as a result of the partial closure of the bay of biscay an interpreted mesozoic crustal scale extensional detachment could be the weakness zone that allowed the lower crust to slide southward under the upper crust resulting in the indentation of the cantabrian margin lower crust into the iberian crust plate convergence stopped at an early stage making this a unique area to study the initial stages of deformation of a passive margin

chronology of fluvial terrace sequences for large atlantic rivers in the iberian peninsula upper tagus and duero drainage basins central spain abstract this work analyses the chronology of fluvial terrace sequences of the two most important fluvial basins from central spain draining to the atlantic ocean upper tagus and duero drainage basins both basins evolved under similar mediterranean climatic conditions throughout the pleistocene and present comparable number of fluvial terraces 16 17 after excluding the higher terrace levels of the tagus t1 t5 entrenched in the rana surface these higher ranizo terraces was formed in response to fan head trenching in this high alluvial piedmont 220 m and therefore not properly controlled by quaternary fluvial downcutting the study accomplishes the implementation of multiple regression analyses for terrace height age relationships to transform relative terrace heights above the present river thalwegs i e 100 m in numerical ages a height age transference function has been developed on the basis of preliminary statistical geochronological approaches proposed for central spain the resultant height age transference function gather 73 published geochronological data for terrace sequences featuring a 3rd order polynomial function r2 0 90 this function describes the overall trend of valley downcutting for the last c 2 3 ma in central spain and is used to assign numerical ages to terrace levels at different relative elevation

fluvial archives a valuable record of vertical crustal deformation abstract the study of drainage network response to uplift is important not only for understanding river system dynamics and associated channel properties and fluvial landforms but also for identifying the nature of crustal deformation and its history in recent decades geomorphic analysis of rivers has proved powerful in elucidating the tectonic evolution of actively uplifting and eroding orogens here we review the main recent developments that have improved and expanded qualitative and quantitative information about vertical tectonic motions the effects of horizontal deformation are not addressed channel long profiles have received considerable attention in the literature and we briefly introduce basic aspects of the behaviour of bedrock rivers from field and numerical modelling perspectives before describing the various metrics that have been proposed to identify the information on crustal deformation contained within their steady state characteristics then we review the literature dealing with the transient response of rivers to tectonic perturbation through the production of knickpoints propagating through the drainage network inverse modelling of river profiles for uplift in time and space is also shown to be very effective in reconstructing regional tectonic histories finally we present a synthetic morphometric approach for deducing the tectonic record of fluvial landscapes as well as the erosional imprint of tectonic forcing sedimentary deposits such as fluvial terrace staircases are also considered as a classical component of tectonic geomorphology we show that these studies have recently benefited from rapid advances in dating techniques allowing more reliable reconstruction of incision histories and estimation of incision rates the combination of progress in the understanding of transient river profiles and larger more rigorous data sets of terrace ages has led to improved understanding of river erosion and the implications for terrace profile correlation i e extrapolation of local data to entire profiles finally planform changes in fluvial systems are considered at the channel scale in alluvial rivers and regional level in terms of drainage reorganisation examples are given of how numerical modelling can efficiently combine with topographic data to shed new light on the dis equilibrium state of drainage systems across regional drainage divides

quantifying the erosional impact of a continental scale drainage capture in the duero basin northwest iberia formerly closed drainage basins provide exceptional settings for quantifying fluvial incision and landscape dissection at different time scales endorheic basins trap all the sediment eroded within the watershed which allows estimates of post basin opening erosion patterns the duero basin was a former closed basin and is presently drained by the duero river into the atlantic ocean during the cenozoic the basin experienced a long endorheic period marked by the formation of continental carbonates and evaporites the retrogressive erosion of the atlantic drainage coming from the portuguese coast subsequently captured the internal drainage and significant fluvial dissection occurred presently the basin contains a relatively well preserved sedimentary fill gridding and surface fitting in this paper provide the first attempt to reconstruct the surface of the top of the former endorheic sedimentary sequence to quantify the erosional impact of the basin opening at least 2251 524 km3 of sediment was removed from the formerly closed basin following the start of exorheism this volume represents a mean basin surface lowering of 65 13 m erosion estimates and landscape dissection patterns are consistent with geologic evidence of progressive establishment of an outward drainage system

dynamics of mediterranean late quaternary fluvial activity an example from the river ebro north iberian peninsula abstract late pleistocene and holocene fluvial evolution of the upper river ebro miranda basin north spain is analysed using geomorphological sedimentological and optical dating techniques maximum regional crustal uplift of 0 98 m ka approximately helped preserve a suite of terraces in the miranda basin 5 river terraces t1 5 were identified and their formation attributed to mis 6 t 1 mis 5d t 2 mis 4 t 3 mis 2 t 4 mis 1 t 5 alluvium deposited in terraces t 1 t 2 t 3 and t 4 is well sorted clast supported gravels whereas the t 5 deposit is exclusively composed of silt gravels were deposited during cold and dry periods when reduced vegetation cover on hillslopes increased sediment supply to the trunk river silt was deposited in overbank settings under warmer and wetter climate conditions when vegetation cover stabilised hillslopes and restricted sediment supply it also resulted in lower peak discharge and reduced flow velocities over vegetated floodplains the chronological sequence of terraces indicates that incision occurred during climatic transitions we conclude that the upper river ebro responded to fluctuations in sediment supply and discharge controlled by late quaternary climate cycles

investigation on the use of geomorphic approaches for the delineation of flood prone areas three different geomorphic approaches to the identification of flood prone areas are investigated by means of a comparative analysis of the input parameters the performances and the range of applicability the selected algorithms are the method proposed by manfreda et al 2011 based on a modified version of the topographic index tim the linear binary classifier proposed by degiorgis et al 2012 which uses different geomorphic features related to the location of the site under exam with respect to the nearest hazard source the hydro geomorphic method by nardi et al 2006 simulating inundation flow depths along the river valley with the associated extent of surrounding inundated areas comparison has been carried out on two sub catchments of the tiber river in central italy the simulated flooded areas obtained using the selected three methods are evaluated using as a reference the tiber river basin authority standard flood maps the aim of the research is to deepen our understanding on the potential of geomorphic algorithms and to define new strategies for prompt hydraulic risk mapping and preliminary flood hazard graduation this is of foremost importance when detailed hydrologic and hydraulic studies are not available e g over large regions and for ungauged basins

tropical atlantic sea surface temperature variability and its relation to el nino southern oscillation past analyses of tropical atlantic sea surface temperature variability have suggested a dipole behavior between the northern and southern tropics across the intertropical convergence zone itcz by analyzing an improved 43 year 1950 1992 record of sst smith et al 1996 and other data derived from the comprehensive ocean atmosphere data set coads it is shown that the regions north and south of the itcz are statistically independent of each other at the seasonal to interannual timescales dominating the data confirming the conclusions of houghton and tourre 1992 some dipole behavior does develop weakly during the boreal spring season when there is a tendency for sst anomaly west of angola to be opposite of that in the tropical north atlantic it is further shown that tropical atlantic sst variability is corre lated with pacific e1 nifio southern oscillation enso variability in several regions the ma jor region affected is the north atlantic area of ne trades west of 40ow along 10on 20on and extending into the caribbean there about 50 80 of the anomalous sst variability is associ ated with the pacific enso with atlantic warmings occurring 4 5 months after the mature phases of pacific warm events an analysis of local surface flux fields derived from coads data shows that the enso related atlantic warmings occur as a result of reductions in the surface ne trade wind speeds which in turn reduce latent and sensible heat losses over the region in ques tion as well as cooling due to entrainment this enso connection is best developed during the boreal spring following the most frequent season of maximum enso anomalies in the pacific a region of secondary covariability with enso occurs along the northern edge of the mean itcz position and appears to be associated with northward migrations of the itcz when the north at lantic warmings occur although easterly winds are intensified in the western equatorial atlantic in response to pacific warm events they do not produce strong local changes in sst contrary to expectations from studies based on equatorial dynamics these teleconnected wind anomalies do not give rise to significant correlations of sst in the gulf of guinea with the pacific enso as the teleconnection sequence matures strong se trades at low southern latitudes follow the de velopment of the north atlantic sst anomaly and precede by several months the appearance of weak negative sst anomalies off angola and stronger positive anomalies extending eastward from southern brazil along 15o 30os

quantifying the post tectonic topographic evolution of closed basins the ebro basin northeast iberia closed endorheic sedimentary basins are key recorders of the climatic erosional and tectonic history of their surrounding topography playing an active role in its evolution by changing the local geomorphological base level when these basins become exorheic the accelerated incision along the new fluvial network can excavate excellent stratigraphic outcrops but this often removes the uppermost infill and essential information about the late basin history is lost here we propose estimating the opening age and past elevation of captured closed basins by combining the flexural isostatic compensation of the eroded volume with available constraints on sediment age we use this method to constrain the post tectonic evolution of the cenozoic ebro basin in northeast iberia the similar results obtained for 4 dated stratigraphic columns show the robustness of the model and date the basin opening as 12 0 7 5 ma with a maximum paleoelevation of the basin of 535 750 m the isostatic rebound associated with basin erosion as much as 630 m in the center of the basin may explain the absence of a canyon excavated by the ebro river during the mediterranean sea level fall associated with the messinian salinity crisis

the intertropical convergence zone in the south atlantic and the equatorial cold tongue recent observations from the quikscat and tropical rainfall measuring mission satellites as well as a longer record of special sensor microwave imager winds are used to investigate the existence and dynamics of a southern hemisphere partner to the intertropical convergence zone in the tropical atlantic ocean the southern intertropical convergence zone extends eastward from the coast of brazil in the latitude band 10 8 38s and is associated with seasonal precipitation exceeding 6 cm month 21 during peak months over a part of the ocean characterized by high surface salinity it appears in austral winter when cool equatorial upwelling causes an anomalous northeastward pressure gradient to develop in the planetary boundary layer close to the equator the result is a zonal band of surface wind convergence that exceeds 10 26 s 21 with rainfall stronger than 2 mm day21 and an associated decrease in ocean surface salinity of 0 2 parts per thousand

tributary effects on fluvial terrace development since the last interglacial in the upper tama river valley central japan abstract to understand the sediment routing system from mountains to lowlands in the quaternary period it is necessary to evaluate the interactions of fluvial processes and their response to climate changes we reconstructed the development of fluvial landforms along the upper tama river valley of central japan since the last interglacial focusing on distinguishing toe cut terraces remnants of tributary fans from trunk river terraces by combining analyses of the sediments and geomorphology of terrace deposits with age dating of tephra and organic matter in these deposits our results show that late in mis 5 the tributaries supplied sediment to the trunk valley that together with sediment in the trunk river elevated the bed of the trunk river in mis 4 and 3 tributary deposits built small fan surfaces around the tributary junctions while trunk river sediment was transported downstream and did not contribute to filling of the trunk valley after the last glacial maximum lateral erosion by the tama river transformed the tributary fans into toe cut terraces and the reworked tributary deposits contributed to the formation of fill cut terraces while helping the trunk river maintain an equilibrium state in the tama river basin the contribution of tributaries to the sediment routing system systematically increased upstream where steeper tributaries with catchment basins of higher relief join the trunk valley more frequently our findings suggest that cutting and filling of tributary sediment around stream junctions contributed buffering effects that have stabilized the bed of the tama river against quaternary climatic changes

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

quantification of fluvial incision in the duero basin nw iberia from longitudinal profile analysis and terrestrial cosmogenic nuclide concentrations the duero basin is one of the largest cenozoic basins in iberia and contains a relatively well preserved sedimentary infill the top of the sedimentary sequence crops out at elevations up to 900 m above sea level the present day basin drains to the atlantic ocean via the duero river through the arribes gorge but during the cenozoic the basin experienced a long endorheic period marked by the formation of evaporites the time the basin opened to the atlantic ocean and the formation of the modern duero river drainage system remains poorly constrained in this study we quantify the spatial distribution of river incision within bedrock and sedimentary units by comparing the nearly relict higher reaches with the lower deeply incised reaches of the tributary system results show an abrupt increase in stream incision westward reaching a minimum bedrock incision depth of 600 m in the arribes gorge using cosmogenic 10be and 21ne data we estimate exposure ages for erosion surfaces at various levels in the incised duero river the cosmogenic nuclide dataset suggests that the final 2 300 m of fluvial incision in the arribes gorge occurred at a rate of 2 3 mm yr over the last 100 ka

erosion surfaces and neogene landscape evolution in the ne duero basin north central spain abstract we present a chronological model of erosion surface development in the iberian and cantabrian ranges of north central spain we map four erosion surfaces and interpret these to be related to duero basin continental sediments and tectonic activity from upper oligocene to plio pleistocene the oldest erosion surface se1 formed across upper oligocene lower miocene synorogenic deposits while surface se2 was contemporaneous with the middle miocene alluvial systems ending with an uplift stage in the astaracian the two most recent erosion surfaces se3 and se4 developed during extensional tectonic episodes and are associated with the deposition of upper paramo sedimentary units at the end of the miocene upper turolian and alluvial fan deposits known as ranas plio pleistocene with the exception of se1 which seems to be associated with a relatively wet climate the surfaces formed during periods of marked aridity and generally warm temperatures through geostatistical reconstruction of the best preserved surface se2 applying ordinary kriging method to the topography dem of the erosion surface and its correlating sedimentary plains we identify the deformation processes which occurred on this surface after its formation

fluvial networks of the iberian peninsula a chronological framework abstract knowledge of the evolution of spanish fluvial networks has improved during recent years as more river systems have been studied and more geochronological data has become available however the chronological framework is a major issue as the range of applications is limited by methodological constraints and spatial coverage is sparse integration of absolute dating methods with biostratigraphy and palaeomagnetism permits the recent evolution of these river systems to be reviewed the timing of incision from the late neogene to the present varies between the major iberian fluvial systems depending on the substrata and tectonic settings early pleistocene and older fluvial sequences in the core areas of the iberian peninsula provide a more extensive record of fluvial evolution and are better preserved than the terrace flights in the coastal lowlands middle pleistocene sequences are well developed in most of the major river systems in iberia particularly those of the tajo guadalquivir and aguas river and frequently represent the principal climatic cycles of that period although tectonic and sea level effects can also be seen for late pleistocene to holocene times the scheme becomes more complex our review suggests that each river system has responded differently to local and regional climate control glacial and periglacial processes in headwaters in high mountain areas glacio eustatic sea level changes and local and regional tectonic patterns

interplay between tectonics climate and fluvial transport during the cenozoic evolution of the ebro basin ne iberia 1 three dimensional modeling that integrates fluvial sediment transport crustal scale tectonic deformation and lithospheric flexural subsidence is carried out to simulate the landscape and drainage evolution of the ebro sedimentary basin ne iberia the ebro basin underwent a long period of closed intramountain drainage as a result of tectonic topography generation at the pyrenees the iberian range and the catalan coastal range in the late oligocene the catalan coastal range underwent extension leading to the formation of the valencia trough nw mediterranean but the ebro basin remained closed for nearly 15 myr more before the ebro river cut through the remnants of the topographic barrier this drainage opening caused widespread basin incision that shaped spectacular outcrops of the syntectonic and posttectonic infill here we investigate the processes controlling these major drainage changes the modeling results constrained by a large data set on the tectonic and transport evolution of the area predict a closed phase characterized by a large lake in the central eastern ebro basin dry climatic conditions probably lowered the lake level and contributed together with rift flank uplift to prolong this endorheic basin stage the age and amount of reworked sediment after the opening are consistent with an onset of basin incision between 13 and 8 5 ma as a result of lake capture by escarpment erosion and lake level rise associated with sediment accumulation and wetter climatic conditions sea level changes in the mediterranean had no major impact in the large scale drainage evolution of the ebro basin index terms 1625 global change geomorphology and weathering 1824 1886 1815 hydrology erosion and sedimentation 3210 mathematical geophysics modeling 3344 meteorology and atmospheric dynamics paleoclimatology 8102 tectonophysics continental contractional orogenic belts keywords pyrenees drainage evolution lake sediment budget erosion flexure

external controls on quaternary fluvial incision and terrace formation at the segre river southern pyrenees abstract focusing on climatic and structural tectonic controls we aim to determine their relative importance for the pliocene to quaternary fluvial landscape evolution in the southern pyrenees foreland we investigate the segre river which is one of the major streams of the southern pyrenees that drains the elevated chain towards the ebro foreland basin along its course the segre river has a flight of fluvial cut and fill and strath type terraces preserved that have been mapped based on dem s and geomorphological fieldwork this paper presents the first results of our study and reports on the segre terrace staircase which is characterized by seven major quaternary terrace levels with elevations up to more than 110 m above the modern floodplain at the upper and middle reaches the semi parallel terraces of the segre river occasionally show anomalies featuring extensive gravel thickness and deformation caused by faulting folding and local subsidence the longitudinal correlations of terrace levels reveal increased vertical terrace spacing in the foreland which could originate from enhanced fluvial erosion after the mid pleistocene climate transition in combination with base level lowering controlled by the progressive downcutting of the catalan coastal range since the ebro basin opening late miocene the catalan coastal range which borders the ebro foreland basin to the mediterranean sea was progressively cut down and the exorheic drainage system gradually adjusted to sea level the segre longitudinal terrace profiles and the ebro gorge morphology at the catalan coastal range indicate a base level of about 200 m s l at the beginning of pleistocene terrace formation which implies that the catalan coastal range might have functioned as a local base level upstream of the sea outlet presumably until the late pleistocene alternatively a yet unknown tectonic process might have caused base level lowering and the preservation of terrace staircases at the ebro drainage system

terrestrial 10 be and electron spin resonance dating of fluvial terraces quantifies quaternary tectonic uplift gradients in the eastern pyrenees the 120 km longt et river flows out of the pyrenees to the mediterranean by displaying a mappable sequence of quaternary alluvial units between the pleistocene frontal moraines of the high range and the offshore sedimentary depocentres its 1400 km 2 watershed is well suited to quantifying gradients of topographic uplift five main generations of terrace treads had previously been inferred from constrasts in regolith weathering features but here we present the first radiometric age constraints based on 15 esr sediment burial ages covering the full sequence and 3 vertical tcn age profiles restricted to three mid sequence terraces analytically robust results were obtained for the oldest and uppermost terrace t5 esr age 1099 179 ka for t3b esr age 374 47 ka mis 10 and for t2 esr age 174 44 ka mis 6 these results are consistent with the contrasts in weathering grade of the deposits the tcn profiles only yielded minimum exposure ages but provided precise post depositional denudation rates for the fluvial terrace treads the land to sea geometry of the chronosequence also provided clues about valley incision rates in response to topographic uplift during the last 1 ma based on a critical review of similar data obtained for other mediterranean and atlantic watersheds in the pyrenees the full regional correlation reveals that post orogenic topographic uplift was substantial and relatively uniform throughout the entire mountain range patterns and magnitudes suggest a shared probably subcrustal driving mechanism of neogene and quaternary mountain growth with only subsidiary influence from isostasy and climatic forcing