comment on formation of chenier plain of the donana marshland sw spain observations and geomorphic model by a rodriguez ramirez and c m yanez camacho marine geology 254 2008 187 196 abstract the application of the regional marine 14 c reservoir effect r to obtain an accurate calibration of conventional marine shell 14 c dates requires prior research concerning the oceanographic conditions and the r of that region rodriguez ramirez and yanez camacho a rodriguez ramirez c m yanez camacho formation of chenier plain of the donana marshland sw spain observations and geomorphic model marine geology 254 2008 187 196 and afterwards a rodriguez ramirez j a morales j borrego and e g san miguel in a reply a rodriguez ramirez j a morales j borrego e g san miguel reply to the comment on formation of chenier plain of the donana marshland sw spain observations and geomorphic model by a rodriguez ramirez and c m yanez camacho marine geology 254 2008 187 196 marine geology 263 2009 123 125 to the comment by j rodriguez vidal f ruiz and l m caceres on the paper mentioned above j rodriguez vidal f ruiz l m caceres comment on formation of chenier plain of the donana marshland sw spain observations and geomorphic model by a rodriguez ramirez c m yanez camacho marine geology 254 2008 187 196 marine geology 263 2009 120 122 use in both cases not only incorrect r values for the calibration of 14 c dates obtained from shell samples collected from the east coast of the gulf of cadiz but they also confuse the r concept with that of r t the 14 c reservoir age because the misunderstanding of these concepts by these authors and in the first case also their failure to take into account the r values obtained by us and already published from the east coast of gulf of cadiz all the calibrated dates presented either in the first paper or in the reply cannot be accepted here i present a new calibrated dataset using accurate r values and i recommend that the conclusions obtained by rodriguez ramirez and their collaborators be revised as j rodriguez vidal f ruiz and l m caceres proposed in their comment

sedimentary record of recent tsunamis in the huelva estuary southwestern spain abstract the coast of the gulf of cadiz has been repeatedly struck by tsunamis during the late holocene and the historic period historical documents record at least seven catastrophic tsunamis affecting this coast while others have been detected by oceanic instruments nevertheless very few studies have documented the sedimentary record of these tsunamis in the low energy coastal environments of the gulf of cadiz the huelva estuary is located at the central sector of the gulf of cadiz and is a mesotidal estuary fed by the tinto and odiel rivers the mean tidal range of the huelva estuary is ca 2 m and the mean significant wave height is ca 0 5 m the outer part of the estuary is characterized by extensive sand rich sedimentary bodies of marine origin whereas the central and inner parts are infilled by muddy tidally deposited sediment bodies recorded within these estuarine sediment bodies are five laterally continuous shelly units these units display many of the typical characteristics of tsunami deposits each typically comprises an erosional base followed by a fining upwards sequence that begins with the shell accumulation and ends with bioturbated muddy sand the results of 14 c ages and recent radionuclides accumulation rates in this study illustrate that these five tsunami deposits correspond with known events that occurred in ad 1755 1531 949 1033 881 and 395 381 all of which are documented in historical sources

fluvial dispersal potential of guanaco bones lama guanicoe under controlled experimental conditions the influence of age classes to the hydrodynamic behavior hydrodynamic sorting is a taphonomic process able to transport and scatter bones deposited in archaeological and paleontological sites this study presents the results of experimentation performed in an artificial flume with guanaco lama guanicoe bones of different ontogenetic development dry and saturated in water in hydric flows velocities of 15 and 30 cm s the obtained results show that bone global density the age of the individual the dry or wet bone state and the hydric flow velocity influence significantly bone dispersion in this way bones from immature individuals with unfused secondary growth centers and relatively low bulk density have better possibility of being transported than fused bones from adult individuals taking into account the results obtained in this experimentation and the feasibility of discriminating age categories in fossil assemblages two bone groups with differential potential transport are presented in this paper these transport groups constitute a methodological tool to evaluate the role hydric current may had played in the formation of a fossil assemblage

alteration and geochemical patterns in the 3 7 3 8 ga isua greenstone belt west greenland abstract volcanic rocks of the 3 7 3 8 ga isua greenstone belt have undergone heterogeneous poly phase post magmatic alteration resulting in mobilisation of many elements including lree and th in contrast nb ta ti zr y and hree were relatively immobile during alteration processes the degree of element mobility appears to have been controlled by chemical composition primary volcanic structures carbonate and silica enrichment and proximity to ultramafic units and shear zones on the basis of the geochemical characteristics of the least altered samples two distinct associations have been recognised in structurally separated lithotectonic sequences these magmatic associations are a low hfse association tio2 0 20 0 40 wt zr 12 30 ppm nb 0 13 0 80 ppm y 6 14 ppm in the central arc sequence resembling tertiary boninites and a high hfse association tio2 0 50 1 14 wt zr 34 77 ppm nb 1 2 2 7 ppm y 11 28 ppm in the outer and inner arc sequences comparable to phanerozoic island arc basaltic to picritic volcanic rocks these two geochemically distinct sequences were likely to have been juxtaposed as a consequence of phanerozoic style plate tectonic processes operating in the early earth the isua volcanic rocks are characterised by sub chondritic nb ta 10 16 ratios post magmatic alteration can be ruled out as the cause of these low ratios rather these ratios reflect a compositional characteristic of the paleoarchean mantle source s the sub chondritic nb ta ratios may have resulted from either preferential sink of nb into the core as a weakly siderophile element or preferential retention of nb in the subducted oceanic crust during subduction zone petrogenetic processes alternatively the building blocks of the earth were not composed of ci like chondritic material

autochthonous anisotropy of archaeological materials by the action of water experimental and archaeological reassessment of the orientation patterns at the olduvai sites abstract anisotropic patterns documented indirectly through m leakey s drawings of olduvai archaeological sites have led to questions about the integrity of these sites most experiments on bone transport by water have been carried out using complete elements that do not replicate specimen bone breakage and size as documented in archaeological sites in the present work an experimental framework is provided using experimental proxies of archaeological assemblages results show that autochthonous assemblages affected by hydraulic processes can adopt anisotropy in their fabric archaeological comparisons between drawings and excavated sites at olduvai stress the bias in leakey s drawings of flk zinj and flk north in bed i a large scale open excavation recently carried out at tk bed ii exposes an area comparable in size to leakey s excavations comparing the orientation patterns of this site to those reported by leakey shows how biased the drawing of the site is and how easily this can lead to misinterpretations of isotropy anisotropy with fatal consequences for the understanding of site formation processes

contrasting high and intermediate pressures of metamorphism in the archaean sargur schists of southern india the archaean karnataka craton of southern india contains eastern and western crustal blocks separated by a major thurst in which sargur schists occur as lenses within tonalitic peninsular gneisses the schist complex comprises pelites quartzitic psammites carbonates and calc silicates iron formations and basic rocks and thus provides many mineral assemblages ideal for the calculation of pt conditions with their gneisses the sargur rocks are unconformably overlain by the dharwar greenstone belts and are generally thought to be older than 3 000 my

taphonomy of some articulated skeletal remains transport potential in an artificial environment flume experiments demonstrated that disarticulated bones did not display the same behaviour when combined as articulated elements the character of movement and rates of movement were recorded skeletal elements were identified as displaying either a transportable or a non transportable potential some of which were common to all three species that were tested the experiments demonstrated that articulated bones displayed a greater transport potential and that in one species the rate of movement was significantly faster than when disarticulated it is suggested that the taphonomic history of a fluvial transported assemblage could be misinterpreted if the bones were treated as a mixture of individually transported elements

late holocene evolution of the southwestern donana national park guadalquivir estuary sw spain a multivariate approach four phases are distinguished in the late holocene evolution of the southwestern donana national park sw spain based on a multidisciplinary analysis of the sediments present in drill cores in the oldest phase 2400 2500 cal yr bp a coastal lagoon the roman lacus ligustinus was recognized in the central part of this area partly closed by the donana spit and limited by fluvial levees the following phase 2400 2200 cal yr bp is characterized by high energy events which caused the breakthrough of the donana spit and the creation of new littoral strands in the inner areas in the third phase 2200 2050 cal yr bp this new outlet was closed coinciding with the progradation of the donana spit the last phase 2050 cal yr bp recent comprises three periods a an unstable period 2050 1950 cal yr bp with the deposit of cheniers over the previous levees b an infilling period with a diminution of the marine influence and c the appearance of temporary ponds between the emerged levees and cheniers

neoarchean magmatism in shimoga greenstone belt india evidence for subduction accretion processes in the evolution of the western dharwar stratigraphy abstract new geochemical and geochronological data are presented for a suite of metavolcanic rocks from shimoga greenstone belt to understand their petrogenesis and to constrain the timing of final mafic magmatic activity in western dharwar craton we report an sm nd isochron age of 2638 66 ma for metabasaltic and metaandesitic rocks of the stratigraphically uppermost medur formation of dharwar supergroup exposed in the belt which is the youngest age obtained yet for neoarchean mafic magmatism in western dharwar craton the emplacement of the basalt andesite dacite rhyolite suite of rocks took place in a magmatic arc culminating in the deposition of vast greywacke argillites in a continental margin type setting the magmatic precursors of the metavolcanic rocks were generated by partial melting of depleted mantle by slab derived fluids with variable input from the subducting slab assimilation fractional crystallization processes may also have contributed to the magmas to a significant extent the younger mafic lithologies of the dharwar stratigraphy represent accretionary orogens and the date obtained in this study points towards the final stages for the assembly of western dharwar craton by subduction processes during neoarchean the thickness and extent of the greywacke argillite suite in sgb could be attributed to the protracted deposition during amalgamation of western dharwar craton with a northern archean continental crust that might underlie deccan volcanic rocks

fluvial transport of bovid long bones fragmented by the feeding activities of hominins and carnivores this study explores the hydraulic transportability of bovid long bone fragments created through hominin and carnivore carcass consumption in order to determine the effect of fluvial transport on the incidences of hominin and carnivore induced bone surface modifications transportability was determined using an oval race track flume and 311 long bone fragments from modern control collections of hominin and carnivore modified bone results show that the fluvial transport of long bone fragments is predicted by animal size class and bone specimen size as measured by maximum cortical thickness maximum length and maximum width all of these variables can be measured on fossil specimens long bone portion midshaft near epiphysis and epiphysis does not affect transport and hydraulic transport does not substantially modify the incidences of tooth percussion and cut marking in transported or lag assemblages in low energy fluvial environments implications of this study are 1 animal size classes and cortical thickness length and width of long bone fragments can be used to identify fluvial winnowing in fossil assemblages 2 analyses concerning the relative timing of hominin and carnivore carcass consumption based on the proportions of long bone fragments bearing tooth percussion or cut marks can be meaningfully applied to fossil assemblages deposited in low energy fluvial environments

late archaean granites a typology based on the dharwar craton india abstract extensive field work in the eastern dharwar craton associated with petrographic and geochemical major and trace elements investigations allows four main types of late archaean granitoids to be distinguished 1 na rich granitoids of trondhjemitic tonalitic and granodioritic composition ttg that are characterised by strongly fractionated ree patterns and low hree contents and generally interpreted as slab melts generated by partial melting of metamorphosed hydrated basalt most likely in a subduction environment 2 sanukitoids which are k and mg rich monzonites and granodiorites with ttg like ree patterns associated with marked lile enrichment and considered to result from the reaction of slab melts generated in a subduction environment with and assimilation of mantle wedge peridotite 3 uncommon high hfse mg and k granites with strongly ree and lile enrichment that probably formed by partial melting of an enriched mantle source unlike in the genesis of sanukitoids in this case the slab melt is considered to be wholly consumed by reaction with mantle minerals resulting in mantle enrichment subsequent melting of this enriched mantle probably in a post subduction setting gives rise to high hfse mg and k magmas as demonstrated for the closepet granite dharwar craton the hot mantle derived magma can induce melting of continental crust and then mix with the anatectic products 4 k rich mg poor anatectic biotite granites with ree patterns that are less fractionated and show negative eu anomalies these granites result from the remelting of old basement or recently accreted plutons both with ttg compositions such anatexis can occur either in a subduction or in a post subduction environment this typology based on the well exposed dharwar craton can be extended to late archaean granitoids from all over the world about such 500 analysis were compiled and a number of discriminant diagrams based on both major and trace elements are proposed the most likely tectonic setting for the observed rock types is an accretionary orogen with accretion of continental blocks above a subduction system followed by thermal reworking of the newly accreted continental material however it has been found that archaean subduction related granitoids are significantly different from their modern counterparts implying progressive changes in the modes of magma generation at convergent margins from the archaean to the present

comment on formation of chenier plain of the donana marshland sw spain observations and geomorphic model by a rodriguez ramirez and c m yanez camacho marine geology 254 2008 187 196 abstract rodriguez ramirez and yanez camacho 2008 rodriguez vidal et al 2009 and rodriguez ramirez et al 2009 have kept an ongoing discussion about the validity of radiocarbon ages in reconstructing holocene palaeogeographical models in the gulf of cadiz the discussion considered the validity and correctness of the r value to be used in the area to calibrate radiocarbon ages of marine samples these papers suggest that the r value proposed by lario 1996 and dabrio et al 1999 2000 is erroneous and consequently that all the evolutionary models based on radiocarbon ages from marine samples that have been proposed in this area since 1996 must be revised however the papers commented here use erroneously the r regional r and r values after reviewing the published data it is apparent that the most reliable values of r in the gulf of cadiz for middle late holocene samples range between r 35 85 yr and r 95 15 yr this means that the values used in lario 1996 and dabrio et al 1999 2000 fall in this range and also that the calibrated ages used by several authors adopting these values are fully reliable calibrations using r values inside this range do not yield significant differences in terms of geological age owing to the magnitude of errors resulting from the methods employed

depositional history of estuarine infill during the last postglacial transgression gulf of cadiz southern spain abstract the late pleistocene and holocene evolution of the estuaries in the gulf of cadiz is interpreted for the first time using drill cores logs trenches and 38 new radiocarbon data and the results compared with the shelf the odiel tinto and guadalete rivers deposited conglomerates during a highstand that did not reach the present sea level dated at ca 25 30 ka isotopic stage is 3 corresponding to a relatively humid period in the area rivers incised these coarse grained deposits during the last main lowstand at ca 18 ka when sea level dropped to 120 m and the coastline lay 14 km seawards from the present the erosional surface is a sequence boundary and the flooding surface of the postglacial eustatic rise overlain by the valley fill deposits of the transgressive and highstand phases of the last fourth and fifth order depositional sequences recognised in the shelf the first marine influence in the estuaries during the transgression occurs at 25 30 m at ca 10 000 years bp according to fossil assemblages the transgressed basins changed from brackish to more open marine as the sea rose until ca 6500 years bp when it reached the maximum flooding and the sandy estuarine barriers ceased to retrograde toward the muddy central basins then the rate of eustatic rise decreased drastically and the estuarine filling followed a two fold pattern governed by the progressive change from vertical accretion to lateral centripetal progradation at ca 4000 years bp the fluvial input surpassed the already negligible rate of rise causing partial emergence of tidal flats and spit barriers in the largely filled estuarine basins prevalence of coastal progradation upon vertical accretion at ca 2400 years bp caused accelerated expansion of tidal flats and rapid growth of the sandy barriers further changes since the 16th century reflect widespread anthropic impacts

one bone two bones wet bones dry bones transport potentials under experimental conditions flume experiments demonstrated that bones had varying hydraulic transport potentials depending on whether the bones were wet or dry articulated or disarticulated when placed into a water flow dry and articulated bones demonstrated the greatest transport potential while wet and disarticulated bones demonstrated the least the velocity at which bones were transported was plotted against a range of attributes such as the shape weight volume and density of the bones with varying degrees of success although several attributes did prove to be significant as indicators of bone transport potential no single attribute emerged as more useful than another

formation of chenier plain of the donana marshland sw spain observations and geomorphic model abstract the guadalquivir estuary is one of the most important in europe it is isolated from the sea by two important littoral spits donana and la algaida its sedimentary filling occurred as a result of deltaic contributions of the guadalquivir river giving rise to marshes primarily composed of mud deposits among which a succession of sandy and shelly ridges can be found the aim of this paper is to explain the genesis and evolution of these sandy and shelly ridges clarifying what types of ridges are found and their spatial distribution identifying the processes responsible for their formation these ridges extend in the form of long strands along the estuary influencing its evolution during the late holocene the geomorphologic and lithostratigraphic features of these ridges allow them to be defined as transgressive cheniers regressive cheniers and laterally accreted ridges spits as components of the guadalquivir estuary chenier plain complex this chenier plain has the peculiarity of developing on a semi enclosed shoreline contrary to other chenier plains in the world which develop on open coasts in the guadalquivir estuary the chenier plain formation is related to two relatively higher sea level 4200 2800 yr bp and 1400 1000 yr bp during which high energy events occur storms and tsunamis that transgressed the large littoral spits the carrizosa 4000 yr bp and vetalengua 1400 1300 yr bp spits have been formed across the inlet and prograded landwards of the estuary from here several sequences of cheniers mainly transgressive cheniers associated with these events were formed these cheniers form two groups las nuevas 1100 1000 yr bp and marilopez 3000 yr bp composed mainly of shells and shell fragments these cheniers were constructed by waves which reworked the shells above estuarine levees and led to their intense landward migration thus explaining the peculiar high inland position of the cheniers

cheniers and chenier plains a general introduction abstract cheniers and chenier plains have been studied in many coastal regions throughout the world an inventory of the investigations currently being carried out is presented in this and accompanying papers cheniers and chenier plains are azonal features their distribution ranges from tropical to the subarctic regions and they show a variety of features progradational shorelines where mud accretion is temporarily interrupted favour the development of these features in addition to the concept of otvos and price who define cheniers and chenier plains as being formed exclusively in relation to littoral progradational environments it is suggested here that chenier formation in deltaic progradational environments should also be included genetically two types of cheniers can be distinguished depending on the origin of the related sediments cheniers developing due to wave winnowing of the muddy sediments and the subsequent concentration of the coarser particles to form a longshore bar or ridge which is driven shoreward and cheniers built by littoral drift in both cases they can be recognised by their sedimentary structures when cheniers arrive onshore they will migrate further landward due to washover processes under extreme hydrodynamical conditions e g spring tides storm surges etc to summarise the information concerning the episodic development of chenier plains in order to produce a or a few universal model s appears to be very difficult owing to the numerous factors that influence their formation these include river mouth shifting sealevel changes climatic changes storm frequency mortality of shellfish and bay geometry owing to this sensitivity to environmental changes during their formation cheniers are considered to be very important geomorphological features they provide a relatively accurate record of sealevel and environmental changes which can be dated with high resolution

biotic and abiotic processes affecting the formation of bk level 4c bed ii olduvai gorge and their bearing on hominin behavior at the site abstract excavations at bk have provided insights into the behavior of early hominins through the study of several archaeological levels the present study shows the results for a new archaeological sub level bk4c the main goal is to contribute to the knowledge of the different taphonomic processes that shaped bk4c and to better understand the role played by hominins in its formation due to the presence of a fluvial depositional context and a slight channel in bk4c a spatial analysis has been applied in order to determine the impact caused by water flows we conclude that water played a role in the rearrangement of the assemblage however the spatial properties of the assemblage indicate a limited impact of post depositional disturbance processes supporting the autochthonous nature of the site the taphonomic study of this sub level indicates that hominins had a primary role in the accumulation bulk defleshing and demarrowing of carcasses bk4 assemblages bk4b and bk4c indicate a repeated occupation of the site for short time periods this is interpreted by the overall fast sedimentation recorded in the fluvial system and the paucity of highly weathered bones showing extensive periods of sub aerial exposure in between sedimentary episodes the site functionality is potentially different from that inferred for earlier oldowan periods where sites were smaller and showed less marked spatial clustering of lithics and stone tools caused by hominin behavior

precambrian tectonics and crustal evolution in south india about 3 4 ga ago voluminous calc alkaline magmas represented by the granitoid gneisses of southern india were emplaced into a now poorly preserved non continental crust unstable ensialic basins initiated at about 3 0 ga were filled with volcanic and sedimentary rocks up to about 2 6 ga this basement cover sequence was deformed at the close of the archaean first by northward accretion and thickening of several crustal slabs formerly separated by prisms of stable shelf sediments structures produced by this episode were refolded and dislocated by large n s strike slip shear belts to impart intense steep planar fabrics to large volumes of the crust fluids rich in co possibly derived from sedimentary material driven beneath the crustal slabs by the thickening mechanism purged the deep crust of h o to form granulites upward migration of hot h o rich fluids encouraged partial melting at intermediate crustal levels these late archaean tectonic and thermal events began soon after the close of basin f

evidence of high energy events in the geological record mid holocene evolution of the southwestern donana national park sw spain abstract four phases are distinguished in the mid holocene evolution of the southwestern donana national park sw spain based on the multidisciplinary study of sediments in drill cores in the oldest phase 5500 5400 cal years bp a coastal brackish lagoon occupied the central part of the study area partly enclosed by the donana spit and limited by fluvial levees an evolution from subtidal to intertidal conditions characterized the areas located close to the inner side of the donana spit during the same phase the following phase 5400 5200 cal years bp is characterized by a high energy event tsunami which caused the breakthrough of the donana spit and the creation of new littoral strands in the inner areas in the first period of the third phase 5200 4200 cal years bp estuarine infilling was probably the dominant process with the accumulation of phyllosilicate rich clays in the lagoon bed this was followed by a renewed phase of instability 4200 4100 cal years bp indicated by the presence of fine storm lain deposits and thicker probably tsunami induced shelly deposits the last phase 4100 3700 cal years bp comprises a an infilling period with a diminution of the marine influence and b two new high energy events which caused the erosion of the donana spit and the creation of new cheniers in the last 7000 years the comparison of these results with a revision of both geological and historical records has revealed the occurrence of twenty tsunamis at least during this period in portugal and southern spain evidences of these high energy events are washover fans bioclastic coarse sized layers within salt marsh deposits or the presence of giant boulders and pebbles the determination of the recurrence period is very difficult owing to the very scarce data although our data and other authors do not discard a possible periodicity of 2000 years for a cycle of two events separated by 300 400 years

whole rock pbpb isotopic ages of late archaean limestones karnataka india application of the pbpb isotopic dating technique to metamorphosed limestones from late archaean low and high temperature greenschist amphibolite facies terrains in karnataka southern india has revealed distinct differences in the evolution of each terrain and in their model 1 values the western low temperature terrain is characterised by tracts of late archaean volcanic and sedimentary rocks dharwar supergroup their basement of orthogneisses and granodiorites 3400 2900 ma and enclaves of older supracrustal rocks intrusions of late archaean granite 2600 ma occur sporadically in the low temperature terrain in contrast the eastern high temperature terrain is dominated by late archaean polyphase syn and post tectonic granites 2500 ma which intruded tracts of supracrustal rocks that are similar to the dharwar supergroup in the low temperature terrain the low and high temperature terrains are separated by a n to nnw trending steep belt of mylonites which is over 400 km in length the pbpb data show that metamorphic recrystallisation of the limestones in the low temperature terrain took place 2639 32 ma ago whereas limestones in the high temperature terrain recrystallised 2475 65 ma ago this finding is consistent with previously published ages of late archaean granites in the low and high temperature terrains limestones from the low temperature terrain have a 1 value of 7 79 whereas those from the high temperature terrain have a 1 value of 8 50 these values suggest that the u and pb that was incorporated in the limestones of the low temperature terrain came from a less evolved source than the u and pb in the limestones in the high temperature terrain and indicate a further contrast between these two divisions of the archaean craton in karnataka the nature of the sources is enigmatic but they may reflect differences in composition of the lithospheric plates that were involved in the dharwar collision system data from the high temperature terrain indicate disequilibrium between the measured pb isotopic ratios of carbonate and residue components of the limestones pb isotopic compositions of hci insoluble residues are consistently more radiogenic than those of associated carbonate minerals and they define a younger rotated palaeoisochron that has no age significance this is the first documentation of carbonate residue disequilibrium on the scale of a single hand specimen it highlights the need for a thorough evaluation of pb isotope systematics and the potential effects of acid leaching for multi component limestones

reply to the comment on formation of chenier plain of the donana marshland sw spain observations and geomorphic model by a rodriguez ramirez and c m yanez camacho marine geology 254 2008 187 196 abstract the application of the regional reservoir effect r on the south atlantic coast of iberia requires adjustments as a result of the variations it has undergone throughout the holocene since 1996 a constant value of 440 84 14c yr has been used dabrio c j zazo c lario j goy j l sierro f j borja f gonzalez j a flores j a 1999 sequence stratigraphy of holocene incised valley fills and coastal evolution in the gulf of cadiz southern spain geologie en mijnbouw 77 23 281 dabrio c j zazo c lario j goy j l sierro f j borja f gonzalez j a flores j a 2000 depositional history of estuarine infill during the last postglacial transgression gulf of cadiz southern spain marine geology 162 381 404 however a constant value for the whole of the holocene cannot be expected which has led to time intervals with different r being established morales j a borrego j san miguel e g lopez gonzalez n carro b 2008 sedimentary record of recent tsunamis in the huelva estuary southwestern spain quaternary science reviews 27 734 746 deduced from the marine reservoir correction database from calib radiocarbon calibration version 5 0 2html by m stuiver p j reimer and r reimer later soares soares a m m 2008 radiocarbon dating of marine samples from gulf of cadiz abstracts annual conference igcp 495 faro portugal 6 7 established a constant r value of 135 20 14c yr which can be applied to samples younger than 4000 14c yr bp rodriguez vidal et al comment on formation of chenier plain of the donana marshland sw spain observations and geomorphic model by a rodriguez ramirez and c m yanez camacho marine geology 254 2008 187 196 marine geology 2009 in press use these disquisitions about the correct r value to question the geodynamic model proposed by rodriguez ramirez and yanez camacho rodriguez ramirez a yanez camacho c m 2008 formation of chenier plain of the donana marshland sw spain observations and geomorphic model marine geology 254 187 196 without providing any data of their own these authors base their particular critique on the chronological difference caused by using a different r value from the one they use which in this case is the soares soares a m m 2008 radiocarbon dating of marine samples from gulf of cadiz abstracts annual conference igcp 495 faro portugal 6 7 value however if we take into account new progress in the r value all studies since 1996 have some kind of chronological error of this kind and therefore this critique should extend to all these works including their own a critique on geodynamic models based solely on chronological differences of this kind is not justifiable at the same time the ages determined by these authors by re calibrating the samples in rodriguez ramirez and yanez camacho rodriguez ramirez a yanez camacho c m 2008 formation of chenier plain of the donana marshland sw spain observations and geomorphic model marine geology 254 187 196 do contain serious errors due to the incorrect use of the calib 5 0 2 programme

recent coastal evolution of the donana national park sw spain abstract since the last holocene sea level rise about 6900 bp a series of depositional littoral landforms has been generated at the outlet of the guadalquivir river with progradation along the predominant longshore drift towards the east the first coastal progradation occurred between 6900 and 4500 bp the donana and perhaps la algaida spits both associated with the oldest and highest marshland in the donana national park are assumed to have been developed at an early stage originally the guadalquivir estuary was wider and deeper than now and its environment was mainly marine the oldest littoral formations have been dated as ca 4735 bp they show erosional events and indicate the breaking up of earlier spit barriers to form inlets the marine environment became increasingly dominant with heavy erosion of cliffs and a retreating coastline this period was followed by another sedimentary cycle 4200 2600 bp that surrounded the earlier eroded barriers the size of the estuary decreased due to the increasing marsh deposits and a fluvial environment was born about 2600 years ago progradation gave way to a new period of intense erosion the resulting morphology of littoral strands and erosional surfaces permitted the return to a marine environment the shoreline again retreated from 2300 bp coastal progradation has prevailed with an erosional interruption at 1000 bp the present day outlet of the guadalquivir is an estuarine delta of inactive marshland the donana national park the dominant environment is fluvial