Large Accommodation Space Research Articles

A compact compliant robot for the grinding of spherical workpieces with high force control accuracy

A robotic grinding system requires a force-controlled grinding module to provide a consistent surface roughness and a robot arm to position the grinding module to reach a wide range of surface area on a workpiece. Existing pneumatic grinding modules are heavy and bulky and cannot provide very accurate force control. Articulated 6-axis robot arms are often used for positioning the grinding module, but they require a large accommodation space and have limited access to the surface of a spherical workpiece. This paper proposes a compact 3-axis grinding robot with no grinding surface limitations on spherical workpieces. The robot employs torque-controlled actuators so that a human operator can easily teach grinding paths to the robot. The proposed grinding module uses series elasticity to generate very low reflected inertia and friction. Hence, accurate grinding force control can be achieved. The grinding module also has a small size and low noise. Experimental results verify the high accuracy of grinding force control when compared with existing counterparts. Through an illustration of removing the parting line of a helmet hardshell, the grinding robot can effectively reduce the surface roughness of workpieces that are sensitive to the grinding force. It is expected that the proposed robot can be easily reconfigured to grind workpieces of different geometries.

Hyphae‐mediated bioassembly of carbon fibers derivatives for advanced battery energy storage

AbstractIngenious design and fabrication of advanced carbon‐based sulfur cathodes are extremely important to the development of high‐energy lithium‐sulfur batteries, which hold promise as the next‐generation power source. Herein, for the first time, we report a novel versatile hyphae‐mediated biological assembly technology to achieve scale production of hyphae carbon fibers (HCFs) derivatives, in which different components including carbon, metal compounds, and semiconductors can be homogeneously assembled with HCFs to form composite networks. The mechanism of biological adsorption assembly is also proposed. As a representative, reduced graphene oxides (rGOs) decorated with hollow carbon spheres (HCSs) successfully co‐assemble with HCFs to form HCSs@rGOs/HCFs hosts for sulfur cathodes. In this unique architecture, not only large accommodation space for sulfur but also restrained volume expansion and fast charge transport paths are realized. Meanwhile, multiscale physical barriers plus chemisorption sites are simultaneously established to anchor soluble lithium polysulfides. Accordingly, the designed HCSs@rGOs/HCFs‐S cathodes deliver a high capacity (1189 mA h g−1 at 0.1 C) and good high‐rate capability (686 mA h g−1 at 5 C). Our work provides a new approach for the preparation of high‐performance carbon‐based electrodes for energy storage devices.

An ultrastable sodium-ion battery anode enabled by carbon-coated porous NaTi2(PO4)3 olive-like nanospheres

NaTi2(PO4)3 (NTP) is a promising anode material for sodium-ion batteries (SIBs). It has drawn wide attention because of its stable three-dimensional NASICON-type structure, proper redox potential, and large accommodation space for Na+. However, the inherent low electronic conductivity of the phosphate framework reduces its charge transfer kinetics, thus limiting its exploitation. Therefore, this paper proposes a material with carbon-coated porous NTP olive-like nanospheres (p-NTP@C) to tackle the issues above. Based on experimental data and theoretical calculations, the porous structure of the material is found to be able to provide more active sites and shorten the Na+ diffusion distance. In addition, the carbon coating can effectively improve the electron and Na+ diffusion kinetics. As the anode material for SIBs, the p-NTP@C olive-like nanospheres exhibit a high reversible capacity (127.3 mAh g−1 at 0.1 C) and ultrastable cycling performance (84.8% capacity retention after 10,000 cycles at 5 C). Furthermore, the sodium-ion full cells, composed of p-NTP@C anode and Na3V2(PO4)2F3@carbon cathode, also deliver excellent performance (75.7% capacity retention after 1000 cycles at 1 C). In brief, this nanostructure design provides a viable approach for the future development of long-life and highly stable NASICON-type anode materials.

Sucrose hybridization modification of polycationic gel to realize super-high adsorption of lignins for reusable purification of wastewater

Sucrose was first used to modify a polycationic gel to form the novel water treatment material of sucrose-hybridized polycationic gel (SHPCG). The new sucrose hybridization effect allowed the SHPCG to show a super-efficient adsorption ability in the purification of papermaking wastewater. The SHPCG exhibited a super-high adsorption capacity toward lignins, reaching 8279.86 mg/g, i.e., the mass of the lignins adsorbed was 8.28 times higher than the mass of SHPCG adsorbent, which was, furthermore, 2.13–41.20 times higher than those of a series of previously reported polycationic adsorbents without the incorporation of sucrose units. Subsequently, the SHPCG wastes after lignin adsorption could be reused directly to purify dyeing wastewater, and maintained its adsorption capacity, being 278.05 times higher than that of activated carbon. Analysis of the interaction mechanisms showed that the sucrose hybridization effect in the polycationic gel skeleton with a large accommodation space had improved the adsorption associativity and interaction intensity of SHPCG toward lignins, and caused the efficient aggregations of lignins in the SHPCG skeleton. This would be the key factor for the super-high adsorption capacity of SHPCG toward lignins. In addition, there was an electrostatic substitution with coating adsorption effect to help in the efficient reuse of SHPCG wastes.

Steering photo-excitons towards active sites: Intensified substrates affinity and spatial charge separation for photocatalytic molecular oxygen activation and pollutant removal

Bismuth oxybromide-based heterostructure has been constructed widely for various photocatalytic application. However, the function of the exposed facets in heterostructure still remains to be elucidated. Herein, we chemically implanted bismuth oxybromide nano-units with dominantly exposed (010) facets on indium vanadate particles to form composites. Results showed that the absorption range of visible light was extended due to the high photosensitivity of InVO4 and the charge transfer was also effectively expedited by the formation of internal electric field. Contrast experiments manifested that BiOBr with dominant (010) facets was more suitable than that with (001) facets to act as electron acceptor in InVO4/BiOBr heterojunction, because the open channels on (010) facets provided large accommodation space for organic pollutants. Thus, the generated superoxide radicals on BiOBr could annihilate the adsorbed pollutants rapidly. Moreover, the hierarchical core-shell structure provided large surface area to further intensify the affinity of InVO4/BiOBr composites to pollutants. Consequently, the hierarchical InVO4/BiOBr heterojunction exhibited excellent photocatalytic activity and could degrade 92.59% of ciprofloxacin (CIP) within 1 h under visible light. The reaction data were fitted with multiple models to investigate the whole reaction process. Furthermore, the impacts of various simulated actual factors on CIP adsorption and degradation were explored. The intermediates and possible degradation pathways were also illustrated through Liquid Chromatography-Mass/Mass Spectrometry (LC-MS). This work not only provide a facet engineering concept for heterojunction construction, but also help us to further understand the relationship between adsorption and photocatalytic degradation.

In2S3 nanosheet arrays grown on the 3D graphene for sensitive detection of epinephrine in the presence of uric acid

In this paper, a simple and efficient electrochemical sensor based on indium sulfide nanosheet arrays (In2S3 NSAs) grown on 3D graphene (3D Gr) has been developed. 3D Gr was obtained by chemical vapor deposition (CVD) and In2S3 NSAs were prepared by a hydrothermal method. The composite (In2S3 NSAs-3D Gr) has a large accommodation space to contact with biological molecules. The current generated by the redox reaction of epinephrine (EP) on the surface of the In2S3 NSAs-3D Gr becomes an important indicator of the sensor value. The sensitivity of the sensor for the detection of EP in the range of 0–60 µm is 2.46 µA µM− 1 with a detection limit of 0.12 µM (S/N = 3). Meanwhile, the novel sensor has a good stability and selectivity. It also has potential for real detection of EP in human serum.

Research on the Sedimentation of Underwater Distributary Channels in Shallow Lacustrine Delta---Case Study of B19-4 Oilfield, Bohai Bay Basin

Based on the data of core observation, grain size analysis, micro paleontology, logging and well logging, the sedimentary environment and characteristics of NmIII and NmIV oil formation in the lower Minghuazhen Formation of B19-4 Oilfield are studied, and the formation reason of narrow strip sand body in this area is explained. The characteristics of formation thickness, lithology, paleontology and sedimentary microfacies indicate that the lower Minghuazhen Formation of B19-4 Oilfield belongs to the shallow water delta deposition of continental lake basin in the background of rising to falling from base level. The sedimentary environment is characterized by gentle slope, large accommodation space, weak hydrodynamic force, far-reaching sediment source, relatively stable structure, etc. the sedimentary sand body is dominated by distributary channel deposition, with developed natural dikes, and undeveloped mouth bars and crevasse fans. Because of this sedimentary environment, the underwater distributary channel of the shallow water delta is not easy to be changed, and the sand bodies of the underwater distributary channel of the multi-stage sedimentary cycles are vertically superposed, forming the sand bodies with narrow strip distribution.

Relationships between tectonic activity and sedimentary source‐to‐sink system parameters in a lacustrine rift basin: A quantitative case study of the Huanghekou Depression (Bohai Bay Basin, E China)

AbstractLacustrine rift basins commonly preserve a fairly complete record of the sediment source‐to‐sink (S2S) system, and consequently may form an ideal natural laboratory for establishing quantitative relationships between the various elements within the S2S system. The tectonic‐activity rate in the source (e.g., fault‐growth rate and fault‐activity rate), accommodation space and depositional system in the sink (e.g., areal extent and volume, as well as the depositional dip of the fan‐ and braid‐deltas) are genetically related and their quantitative correlations are explored. The Palaeogene succession on the southwestern margin of the Huanghekou Depressionin the Bohai Bay Basin, one of the largest lacustrine rift basins in eastern China, was chosen to study these relationships, using 3‐D seismic, core and well‐log data. The tectonic activity was strongly related to the sediment supply, accommodation space and morphology of the sink area. Three different rates of tectonic activity are identified; these led to changes in the basic features of the S2S system that influenced each other. In Members 4 and 3 (lower unit) of the Shahejie Fm. (40.44–44.7 Ma), strong tectonic activity led to significant uplift, resulting in the widest exposure of the provenance area to erosion, to a high sediment‐supply rate, to a steep slope and to a large accommodation space which controlled the development of several fan‐deltas with steep progradational angles. In Member 3 (upper unit) of Shahejie Fm. (37.89–40.44 Ma) and Member 3 of Dongying Fm. (30.2–33.28 Ma), decreased tectonic activity led to slower uplifting, resulting in a wider alluvial plain, longer transport distances, a lower sediment‐supply rate and less accommodation space, so that braid‐deltas with larger volumes and a gentler slope developed; In Members 1 and 2 of Shahejie Fm. (33.28–37.89 Ma) and Member 2 of Dongying Fm. (26.71–30.2 Ma), still further decreasing tectonic activity led to a still lower sediment‐supply rate, a more gentle depositional slope, less accommodation space, and the development of several braid‐deltas with a gentle angle. The quantitative relationships established here advance our understanding of the relationships within lacustrine source‐to‐sink systems, especially for tectonically controlled rift basins.

Structural style, formation of low angle normal fault and its controls on the evolution of Baiyun Rift, northern margin of the South China Sea

Recent studies of high-resolution seismic reflection profiles in the northern rifted margin of the South China Sea revealed that low angle normal faults dominated the structural evolution of deepwater basins rather than high angle normal faults solely as was previously assumed; however, none of the studies proposed kinematic restorations of the fault system and the relationship to continental margin formation. The Baiyun Rift is located in the slope of the northern margin of the South China Sea underlain by extremely thinned continental crust. It is filled with a relatively complete sequence of Cenozoic sediments up to 10 km and has been considered the best-documented deepwater basin. Basin-wide 3D seismic data together with the available deepwater well data have allowed the structural framework to be built and tectono-stratigraphic history of the Baiyun Rift to be traced in detailed from the rift stage; a quantitative study of the primary geometry and kinematics of the major faults can be performed consequently. Results show the inception of the rift is characterized by faults slipped at high angles; the later stage (mid-Eocene) of intensive extension is dominated by a fault system with large horizontal displacements (>10 km) and initial low dips (<30°). The observations can be best explained by a low angle normal faulting (faults started out at shallow angles during mid-Eocene or being rotated from high angles) following a scattered high angle normal faulting. As a consequence, the polyphase faulting created a large accommodation space vertically and horizontally and formed a deep and wide shape of the Baiyun Rift. Besides, the phenomenon that the cessation of the rift in the Baiyun Rift predated the final breakup of the continental margin suggests the timing of the rifting events along the northern margin of the South China Sea is non-instantaneous. This study implies the progressive deformation dominated by low angle normal faulting causes an uneven distribution of the continental crustal thickness and may favor the breakup location in the northern South China Sea.

Basin evolution and oil shale deposition during Upper Cretaceous in the Songliao Basin (NE China): Implications from sequence stratigraphy and geochemistry

The controlling factors of oil shale formation within the Upper Cretaceous Qingshankou and Nenjiang Formations of the Songliao Basin are investigated by petrological and geochemical methods. Sediment deposition was balanced by basin subsidence, resulting in the accumulation of Cretaceous strata of high thickness. Global sea level fluctuations have been related to periods of oil shale deposition within the basin. The results indicate a comparable depositional environment during oil shale formation within the two Upper Cretaceous strata with respect to palaeotectonic and palaeoclimate, but differences in the accommodation space during accumulation of the two formations. The larger accommodation space during deposition of the Nenjiang Formation resulted in the higher thickness and wider distribution of the oil shale members (total thickness: 11.2–32m; distribution area 4.48×103km2) within the basin, as compared to the oil shale of the Qingshankou Formation (total thickness: 2–19.3m; distribution area 1.3×103km2).Further differences exist with regard to the palaeoenvironment of oil shale formation and primary productivity. Deposition of the Qingshankou Formation 1st member and Nenjiang Formation 1st member took place within a saline-brackish lake under anoxic conditions in the bottom water. Preservation of organic matter is suggested to have been less favorable during deposition of the Nenjiang Formation 2nd member. Higher primary productivity is believed to be the responsible factor for the accumulation of organic-rich sediments in the Qingshankou Formation 1st member. The interplay of these two factors (i.e. preservation, productivity) leads to the formation of oil shale in the Qingshankou Formation (average TOC: 8.32%; TOCmax: 13.52%; average oil yield: 5.57%/) with better hydrocarbon source rock potential and slightly higher oil yield during pyrolysis as in the Nenjiang Formation (average TOC: 7.76%; TOCmax: 9.7%; average oil yield: 5.54%).Primary productivity is suggested as the main controlling factor on differences in oil shale quality and source rock potential between the two formations, whereas the variations in quality within each formation mainly depend on the preservation of organic matter. The high thickness, wide spatial distribution and excellent hydrocarbon potential of the Upper Cretaceous oil shales in the Songliao Basin are suggested to have been the result of large accommodation space, stable palaeoenvironmental conditions, and high primary productivity.

Palaeogene sequences with sedimentary characteristics controlling the lacustrine oil shale of the Meihe Basin

As a case study, the Meihe Basin, a typical Cenozoic faulted basin, was divided into and identified as five three-order sequences by utilizing core, well logging, and seismic data, as well as palaeontological and geochemical data. Field measurements of sections, core observations, and a comprehensive analysis revealed that the basin is mainly composed of deposits of alluvial fan, fan delta, lacustrine facies, and gravity flows, and oil shale is mainly developed in semi-deep and deep lacustrine environments. The comprehensive study of the sediment-sequence stratigraphy indicates that Sequence I was formed in the initial rifting stage of the basin, dominated by coarse clastic sediments of alluvial fan and fan delta. Sequence II was formed in the rifting expansion stage of the basin, with more developed sediments of fan delta and lacustrine. Sequence III was formed in the largest expansion stage of the basin, dominated by mudstone of deep lacustrine facies and gravity flow deposits. Sequence IV was formed in the shrinking stage of the basin, dominated by sediments of delta and lacustrine fan. Oil shale are mainly developed in the transgressive system tract (TST) and highstand system tract (HST) of Sequence III (Mudstone Member of lacustrine facies). The lake flooding effect of TST can reduce the decomposition amount of organic matter, increase in organic matter production, and reduce the amount of dilution, thus forming oil shale with a thin consistency but high quality. In the period of the HST, the larger accommodation space and excellent organic matter preservation conditions are conducive to developing stable oil shale with a greater consistency. During the high water level period, however, due to the oxygen brought in by turbidites, the decomposition of organic matter is often increased, resulting in the formation of low-quality oil shale.

Laurentide Ice Sheet dynamics in the Bay of Fundy, Canada, revealed through multibeam sonar mapping of glacial landsystems

Recent multibeam sonar data collected in the Bay of Fundy, Canada, interpreted in conjunction with geophysical profiling and sediment sampling, reveal in unprecedented detail a suite of glacial landforms associated with the southwest margin of the Laurentide Ice Sheet. These landforms constitute four glacial landsystems. 1) Subglacial landsystem I: In southwestern Bay of Fundy, the elongated Grand Manan Basin contains ice-contact sediments of possible mid-Wisconsinan age overlain by late-Wisconsinan ice-contact sediments strongly imprinted by iceberg furrows and pits. In places, possible mid-Wisconsinan glaciomarine sediments have been eroded by late-Wisconsinan ice, creating streamlined landforms. Eroded bedrock and megafluted ice-contact sediment on the flanks of Grand Manan Basin indicate the southwest direction of topographically-steered ice. 2) Subglacial landsystem II: Along the southern margin of the Bay of Fundy, an array of drumlins, with superimposed esker complexes, was formed by glacial ice that emanated northwest from the interior of Nova Scotia and was deflected to the southwest by the ice flowing out of the Bay of Fundy to the Gulf of Maine. The esker complexes formed later when the Nova Scotia ice sheet stagnated and meltwater escaped northwest via topographic gaps. 3) Ice-marginal landsystem I: In northern Bay of Fundy, both small De Geer moraines and larger, basin-bounding moraines were created when retreating late-Wisconsinan ice became grounded in relatively shallow water. New radiocarbon ages show that the Owen Basin Moraine in this landsystem was abandoned prior to c. 14,600 14C yr BP (cal BP 17,015–17,270 [0.7], 17,286–17,405 [0.3]). 4) Ice-marginal landsystem II: This distinctive landsystem consists of numerous arcuate moraines, commonly superimposed on one another. This landsystem was formed by thin (170 m), lightly grounded ice that retreated northeast into the Bay of Fundy. The splayed pattern of the ice margin was a response to a large accommodation space and velocity variations within the ice. The Isle Haute Moraine is a large lobate moraine; its age is poorly constrained by shells from glaciomarine sediments (13,750 ± 60 14C yr BP (cal BP 15,970–15,996 [0.03], 16,047–16,665 [0.97])) but the moraine may be coeval with the onset of a terrestrial ice margin established at the head of the Bay of Fundy by c. 14,300 14C yr BP (cal BP 16,824–17,013).

Sequence palaeogeography and coal accumulation of inland faulting basin: an example from late Triassic Yangtze platform of China

To unveil the formation mechanism of key sequence boundaries of inland faulting basin and coal accumulation characteristics of coal seams in isochrohal stratigraphic framework, sequence stratigraphy, palaeogeographic recovery and other methods were used to research the sequence stratigraphy and coal accumulation in the example of Baoding Basn in the west margin of Yangtze Platform, and the authors advanced a coal accumulation model of Faulting basin on the basis of accommodation space changes in the background of palaeogeography of sequence framework. The results show that: normal lacustrine regression and forced lacustrine regression are the main driving forces for the formation of sequence boundaries of Faulting basin; basement subsidence is the main source of accommodation space of Faulting basin; and subsidence disequilibrium is the main cause for the difference in generation rate of accommodation space of Faulting basin. Coal accumulation in Faulting basin is obviously controlled by accommodation space changes in sequence framework and basin evolution. As Faulting basin evolves into depression basin, both subsidence rate of basin basement and generation rate of accommodation space decrease vertically, it appears as a progradational reverse-graded sedimentary sequence, coal accumulation in secondary sequence framework intensifies first and then weakens, and coal accumulation at the middle stage of highstand system tract is the best. During steady rifting period, minable coal seams were mostly developed in initial lacustrine flooding surface of fourth-order sequence and at the middle-late period of highstand system tract, and coal accumulation center lay in palaeogeographic unit of delta plain with moderate available accommodation space. During shrinking period, minable coal seams gradually migrated to the maximum lacustrine flooding surface and coal accumulation center lay in palaeographical unit of lacustrine with large available accommodation space.

Multiple controls on rift basin sedimentation in volcanic settings: Insights from the anatomy of a small Early Cretaceous basin in the Yanshan belt, northern North China

This paper deals with a small continental rift basin in a volcanic setting and tries to decipher potential controls on its synrift sedimentation. The Luanping basin, which is a well-exposed Early Cretaceous rift basin in the Yanshan belt on the northern periphery of the North China block, was chosen as a case study. We show that extensive and vigorous volcanism took place just prior to the onset of basin formation and continued into a synrift period. Basin fills consist predominantly of lacustrine, fan-delta, braid-delta, and volcaniclastic deposits. Lacustrine facies are composed mostly of deep-lake deposits that appear to have been established soon after basin initiation. Fan-delta systems developed along two high-angle border faults, the master northern Hongqi fault and the secondary western Xiaobaiqi fault. Fan-delta fronts were built up primarily by gravelly and sandy debrites and turbidites. Braid-delta deposits are restricted to the eastern corner of the basin and are characterized by an aggregation of braid-plain conglomeratic deposits. Underwater extrusions of magma and pyroclastic flows are inferred from the presence of volcanic breccias, ignimbrites, andesitic pillows, and peperites, which are enclosed by host lacustrine deposits. Deep-lake and fan-delta systems persisted throughout the synrift period, indicating a rapid subsidence rate, with both adequate sediment and water supply. The high-angle border faults are thought to have played a critical role in creating large accommodation space, and simultaneous displacements of the Hongqi and Xiaobaiqi faults led to the localization of a major depocenter in the western part of the basin. One-dimensional backstripping analysis of three stratigraphic sections shows that the Luanping basin experienced marked synrift tectonic subsidence up to 2 km at a subsidence rate close to 0.2 mm yr −1 . We propose that the high rate of basin subsidence might have been caused mainly by left-lateral transtensional faulting and was enhanced by the superposition of basement downsag induced by underlying magma withdrawal. A predominance of volcanic particles in both debrites and sandstones suggests that source areas were erodible volcanic edifices. A humid paleoclimate is inferred, which not only provided enough water supply, but also promoted weathering of volcanic rocks in source areas, thus maintaining both the deep-lake environment and sediment influx. We conclude that relatively small and isolated rift basins in volcanic settings can experience both rapid subsidence and receive thick lacustrine deposits if they are under the combined control of favorable structure, climate, and magmatism. The model proposed here is believed to be applicable to other rift basins in similar volcano-tectonic settings.

Carboniferous-Permian long-term sea-level change inferred from Panthalassan oceanic atoll stratigraphy

This paper traces late Palaeozoic second-order sea-level change based on the stratigraphy of the Akiyoshi Limestone, an accreted Carboniferous-Permian Panthalassan atoll carbonate succession in SW Japan. The estimated subsidence of a volcanic edifice and the variable rate of carbonate accumulation reveal the long-term sea-level history of the late Palaeozoic. During Bashkirian time, just after the lowstand stage at the mid-Carboniferous boundary, a slow progressive long-term sea-level rise began. This sea-level rise then increased greatly during Moscovian time. The following Kasimovian to Asselian interval represents a stable highstand stage. Beginning in the Sakmarian, sea level fell slowly and became stable in the Yakhtashian (= Artinskian). This stable sea level was maintained into the Midian (= Capitanian), although a small-scale sea-level rise of approximately 55–70 m is recognized in the Murgabian (= Wordian). The most noteworthy aspect of this change of sea level is the rapid sea-level rise during the Moscovian that created a very large accommodation space and resulted in accumulation of a thick carbonate succession. The eustatic rise from the earliest Bashkirian lowstand to the latest Moscovian highstand had an amplitude of approximately 230–240 m. Such a large-scale eustatic rise in the long-term sea-level change would most likely be caused by greater uplift of the ocean floor along the mid-oceanic ridges, as a result of an increase in the production of oceanic crust during that time.

Morpho-sedimentary evidence of Holocene coastal changes near the mouth of the Gironde and on the Medoc Peninsula, SW France

The Medoc Peninsula is a triangular area of land between the Atlantic Ocean on the west and the Gironde estuary on the east. The Gironde, orientated SE-NW, is the largest estuary in France. On the Medoc Peninsula Holocene sediments cover a substratum of Tertiary limestones and Plio-Pleistocene fluvial terraces. The Gironde originated as an incised valley during the Weichselian glacio-eustatic fall (100 000–18 000 B.P.) and has acted as a sink for fine sediment throughout the Holocene sea level rise (SLR) (18 000 B.P. onwards). Conversely, the Atlantic littoral zone, characterised by sandy beaches and dunes, has been subjected to erosion throughout the Holocene transgression. The incised valley of the present Gironde was inundated by the sea approximately 10 000 B.P. At this time, the rate of SLR exceeded that of sediment supply, producing a large accommodation space in which transgressive tidal-estuarine muds and sands were deposited. As the rate of SLR decreased around 6000-4000 B.P., sedimentation became more pronounced and the available accommodation space began to decrease significantly. Landward-derived fluvial sediments began to prograde over the tidal muds and sands, and a first generation of salt marshes formed in the lateral valleys. Around 2575-1420 B.P., a sandy chenier ridge formed at the edge of a first generation of salt marshes and wholly or partly separated them from the Gironde. On the eastern side of the ridge a second generation of marshes began to form after 1200 B.P. Reclamation of the first and second generations of marshes occurred during the seventeenth and eighteenth centuries, respectively. On the estuarine side of the eighteenth century dyke the modern intertidal flats and salt marshes began to form after the eighteenth century. Sedimentation within the estuary decreased the accommodation space and led to the increased transport of sediment to the shelf after 2 000 B.P. This process was also aided by climatic and anthropogenic factors. Future evolution of the Gironde estuary is likely to consist of further marsh growth and chenier development. However, future increases in the rate of SLR, and the degree of storminess, may cause a shift to an erosional regime in parts of the lower estuary. According to previous work [25, 66], three different dune fields migrated landwards across the Atlantic littoral zone over the Holocene period. A field of isolated barchan dunes moved landwards over the Plio-Pleistocene fluvial terraces before 5100 B.P. From some time after this, until around 3000 B.P., a field of parabolic dunes was active. Finally, a barchan dune field was active from around 3000-2000 B.P. to the end of the eighteenth century/beginning of the nineteenth century, when the dunes were stabilised by pine plantations. It is tentatively suggested, using these dates and dune morphology, that dune formation was controlled by sand supply governed by the rate of SLR. However, the role of climatic changes such as aridity, storminess, windiness and the associated effects of vegetation cover, is also likely to be important. In the future the Atlantic coast is likely to continue to erode, although the extensive plantation of the aeolian dunes with pine forests is likely to prevent large-scale transgressive activity.