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The aim of this paper is to evaluate the position of the Holocene transgression on the coast of the Valencia Gulf. To achieve this goal, a sedimentological and micropaleontological analysis of samples of fossil benthic foraminifera in cores from six boreholes drilled in three different wetlands (Almenara marsh, Moro marsh and Valencia lagoon) was carried out. In order to assess the extent of sea level change, at least three factors must be taken into account: 1) eustatic rise (global scale) 2) neotectonics (regional scale) and 3) the sedimentary factor (local and regional scale). Regarding the first factor, some authors have noted that the Holocene transgression reached +1 m above the current sea level in this area. As for the second factor, while the Valencia lagoon is located on a subsiding coast the northernmost marshes are located on a tectonically stable coast. Finally, sedimentation rates are highly variable depending on the area; whereas in the Valencia lagoon the shoreline generally shifts seawards (progradation) in the northernmost areas the coast is currently undergoing retrogradation, although the anthropic factor clearly interferes with this pattern. One of the main conclusions is that in the Valencian coast the Holocene maximum relative sea level did not exceed the present-day one, except in the case of the subsiding area of the Valencia lagoon. The calculation of sedimentation rates, the relative sea-level curve and the evolution of the water column in the different wetlands seem to corroborate it. Radiocarbon and AAR analyses allowed us to date the maximum extent of the Holocene transgression on the Valencian coast at around 5500 cal yr BP in all cases. Despite the different subsidence the three studied wetlands reflected the predominant marine influence until 5500–5200 BP, which was later followed by a growing fluvial or continental incidence, when glacioeustatic adjustments defined the patterns of coastal progradation. [Display omitted] • Location of the MIS 1 coastline position in three West Mediterranean wetlands. • The global Holocene eustatic rise invaded the three wetlands at least 5300 years BP. • Subsidence rate determined different MIS 1 relative sea-level rise in the wetlands. • Tectonic stability in the northern wetlands involved slower relative sea-level rise. [ABSTRACT FROM AUTHOR]

The approach and results of our 2019 paper (Brooke et al., 2019) have been criticised by Dougherty (2022). We examined the sensitivity of a tropical, coarse sand strandplain to changes in relative sea level as expressed through beach-ridge morphology and the elevation of beach berms preserved in the succession of cyclone-generated beach ridges at Cowley Beach, Queensland, Australia. Rather than presenting a new sea-level curve for this region as suggested by Dougherty, our 2019 study of the Cowley Beach strandplain revealed that when compared with the modelled Holocene relative sea-level record and sea-level indicator data for north-eastern Queensland, the strandplain morphology and stratigraphy provide a first-order representation of sea-level position. Importantly, Dougherty (2022) has overlooked the processes involved in the formation of beach ridges at this site and the spatial coverage of our analysis of the strandplain morphology. Both these factors are fundamental to the approach and conclusions of our 2019 paper. We reiterate here that the Cowley Beach strandplain morphology and succession of beach-berm deposits have elevation patterns that match well the broad trend in the regional relative sea-level model for the past 7 ka. We highlight those key beach-ridge formative processes and data limitations neglected in the Dougherty Comment. Finally, we note the challenges and opportunities for further research into the sedimentary records preserved in this distinctive type of tropical strandplain. • First-order changes of sea level can be detected in the Cowley Beach strandplain. • The coarse sandy ridges comprise a berm capped by cyclone-generated surge deposits. • Processes forming these ridges are in marked contrast to temperate strandplains. • There is negligible aeolian deposition contributing to these low-relief ridges. • Uncertainties in ridge elevation, age and GPR data limit sea-level reconstruction. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a novel method to reconstruct sea-level change in coastal freshwater back-barrier marshes. Freshwater environments have long been considered to be unsuitable for the reconstruction of Holocene sea-level changes as they provide limiting, rather than precise, sea-level index points. We recorded the stratigraphy of a small beach and back-barrier coastal Phragmites (reed) marsh at Hallsands, south Devon, southwest England, using hand-drilled cores and ground-penetrating radar, and collected five new sea-level index points from the base of a Holocene peat sequence to refine the regional Holocene relative sea-level curve. We demonstrate that the samples, despite their freshwater origin, yield accurate sea-level index points as determined from the quantifiable relationship between tide levels and groundwater. By means of water-table monitoring and groundwater modelling we show that the primary controls on the water table in the marsh are: (1) stratigraphy; (2) peat permeability; and (3) recharge rates in the back-barrier marsh. The five index points document relative sea-level positions between 7200 and 2400calyr BP. Three points are in good agreement with previously collected regional data from intertidal deposits and two points usefully fill gaps in the existing reconstruction. An amended Holocene relative sea-level curve for south Devon, based on 30 data points, is presented. We conclude that the combined approach of data collection and modelling used in this paper can be applied to similar coastal settings around the world and allows the collection of sea-level index points from locations not previously thought suitable for this purpose. [Copyright &y& Elsevier]

This paper analyzes the sedimentary record of a paleo-inlet that evolved in association with a coastal barrier, using data that provides a high-resolution stratigraphy. During the evolution of the Guaratuba Holocene barrier, autogenic factors associated with the paleo-estuary dynamics compete with allogenic factors of RSL (Relative Sea Level) variation and the influence of climate on sediment input. The integration of geological mapping, vibrocore, GPR (Ground Penetrating Radar), and radiocarbon dating techniques allowed for recognizing of a paleo-inlet migrating east-southeast during the turning point between the transgressive and regressive stages, cyclically affected by episodes of aggradation and reversal in the direction of lateral migration. This dynamic, conditioned by shadow zones of bedrock elevations and the littoral drift of sediments, modifies the stratigraphy and the barrier's depositional architecture, defining diachronous surfaces and lateral variations in the stratigraphic stacking. These features exemplify how barrier-inlet systems are affected by the combination of high frequency, climate-defined events and local coastal processes during their evolution. • Coastal barrier stratigraphy reveals paleo-inlet migration during Holocene sea level rise. • Autogenic and allogenic factors shape barrier-inlet systems during evolution, forming diachronous surfaces. • Barrier progradation and spit/inlet migration characterized by radarfacies, radiocarbon ages, and sedimentary facies. [ABSTRACT FROM AUTHOR]

The Danube delta is one of the few large deltas in the world the evolution of which has involved numerous and varied episodes within a complex framework of interactivity between river sediment supply, allochthonous sediments supplied by longshore currents, marine dispersing forces, vertical movements (neotectonics, sediment compaction) and sea level. The resulting complex morphology comprises diversified landscapes varying from labyrinthic net of channels and lakes (fluvial delta) to massive tracts of monotonous reed marshes, large lagoons divided by barriers, or beach-ridge plains accommodating large transgressive dunefields (maritime delta). Whilst previous studies have focused on various sectors of the Danube delta, the current paper proposes for the first time an integral reconstruction of delta evolution based on existing and new sedimentological and morphological analyses and absolute ages (AMS 14 C and OSL), enabling a comprehensive synthesis in terms of both evolutionary phases and growth patterns. A chronological framework was established for all the deltaic lobes and beach-ridge plains, highlighting the relationship between formation timespan, growth rates, and the resultant morphology. This work unveils the early stage of delta formation, including the reconstruction of delta front advancement into Danube Bay (Old Danube lobe: prior to 7.5–5.5 ka) and initial spit/barrier development (6.7/6.5–5.8 ka). Inception of the bayhead delta started > 1000 yr before the relative stabilization of sea level and of the initial spit formation. The original fluvial delta plain topography is now buried at a depth of 4–6 m depth below the present topography (representing the current stage of fluvial aggradation), as a result of subsidence and sea-level rise. Regarding the maritime delta, six large open-coast lobes developed in the last six millennia, of which four were formed by the Sf. Gheorghe branch, attesting the long uninterrupted activity of this branch, whereas the other two were created respectively by the Sulina and the Chilia branches. The evolution of each lobe is derived from successive (chronological) shoreline positions and discussed in relation with changes in Danube discharge. Special attention has been paid to their growth stages and progradation rates. For the southern delta, we bring in new arguments for an active southern distributary (the Dunavăţ, derived from the Sf. Gheorghe branch) that formed successive open-coast lobes between 2.6 and 1.3 ka. Additionally, we discuss the effects of modern anthropogenically-driven fluvial sediment reduction on the morphology and morphodynamics of the active lobes of the Danube. [ABSTRACT FROM AUTHOR]

Beachrocks represent a significant paleo-environmental proxy because they can record both the vertical and the horizontal evolution of the shoreline. They have often been used to assess Holocene shoreline evolution and crustally induced Relative Sea-Level (RSL) changes in the Mediterranean Sea. In this paper, we used submerged beachrocks from Paros and Naxos Islands (Aegean Sea, Greece) to reconstruct the shoreline modification and provide new insights on the RSL evolution in central Cyclades. Paros and Naxos Islands are of great importance in terms of archaeological evidence of coastal occupation. However, the evolution of their coastlines was seldom explored. In this study, we coupled detailed underwater surveys, analysis of aerial photogrammetry, microstratigraphic analysis and luminescence dating to study beachrock outcrops found down to about 6 m below the present sea-level. We, then, spatially and chronologically constrained some major palaeogeographical changes of a number of coastal sectors of the two islands. Furthermore, the multiple analyses of beachrocks, sediment coring and archaeological data suggested that RSL rose by at least 3.8 m in the last 4.0 ka and that RSL variation in the last 2.0 ka did not exceed 2 m with respect to the present mean sea level. [ABSTRACT FROM AUTHOR]

Prograded barriers are depositional coastal landforms which preserve past shoreline locations and have been studied in order to understand the fundamental drivers of barrier formation. This paper reconstructs the Holocene history of the Seven Mile Beach, prograded barrier in Tasmania, Australia using optically stimulated luminescence (OSL) dating, ground penetrating radar (GPR), light detection and ranging (LiDAR) elevation models and sedimentological analyses. Shoreline progradation of the barrier commenced around 7300 years ago and continued to near present despite a ~ 3000 pause in deposition between 6700 and 3600 years ago indicative of substantial changes in sediment availability. GPR imaged subsurface structures contain a record of seaward dipping reflectors preserved as sediment supplied beaches and dunes leading to shoreline progradation. In the past 500 years a large transgressive dune has formed, built from reworked barrier sands, and now dominates the eastern portion of the barrier implying that shoreline progradation has ceased. This study reaffirms the notion that relict foredune ridges are strongly aligned with modal wave refraction patterns in planform and emphasises the importance of sediment delivery as a key driver of shoreline progradation through beachface and dune accretion. The substantial pause in shoreline progradation on this barrier system, as observed on others around the world, requires further explanation. Although changes in sediment delivery have been inferred, it may also be appropriate to reopen the debate on Holocene sea-level change in Tasmania. [ABSTRACT FROM AUTHOR]

This study presents spatiotemporal paleo-sea-level reconstructions from Abrolhos archipelago and Abrolhos Bank, and fill in a coastline gap of 500 km where no precise paleo-sea level reconstruction exists. The reconstructions are based on sedimentary, biological and geomorphological evidences. The data indicates sea-levels up to 2.9 m higher than the current one between the Mid- to Late Holocene, in agreement with the empirical sea-level envelope and with predictions of geophysical sea-level models for the Brazilian coast. The data suggests that there was little, if any, hydroisostatic compensation across 55 km of the continental shelf in the study area, between the archipelago and the mainland coast, given that similar elevations of the post-glacial sea-level maximum exist in both places. • Broken and tilted coral pinnacles on Abrolhos Bank that can be misleading evidence of higher Holocene sea levels. • This paper presents paleo-sea level reconstructions at Abrolhos Archipelago, located 55 km away from Brazilian mainland. • The reconstructions indicate Holocene paleo-sea levels between 3.1 m and 2.5 m above present one. • The reconstructions are in agreement with predictions of sea-level models and with empiric data for mainland Brazilian coast. • The reconstructions are contradictory with recently published paleo-sea levels from the same area. [ABSTRACT FROM AUTHOR]

Cliff erosion is of concern along inhabited coastlines especially under a scenario of increasing sea level rise. Extrapolation of past erosion rates are often used as a first approximation of future rates, which are or form part of the input into numerical models. However, cliff erosion rates in the Holocene are poorly understood. This is due to the generally short record based on historical maps, which can mask or accentuate erosion rates based on different event frequencies, and, for the more recent cosmogenic exposure dating method, it reflects the large number of variables influencing the concentration of cosmogenic nuclides in rocks at the surface of intertidal shore platforms. The study uses historic maps that go back 400 years, updated (to 2020) recent erosion rates, evidence from mid-Holocene terrestrial habitats in front of present-day cliffs, and a geomorphological landscape type interpretation to provide a better understanding of cliff evolution and erosion history for the cliffs in East Sussex (Southeast England). The paper demonstrates that cliff erosion can only have started in the last few centuries with remnants of Eemian cliffs still present in places. This is supported by published 10Be data. The coastline investigated also shows a persistent decrease in erosion rates to less than half the maximum rate observed in the late 19th to early 20th century despite sea level rise. As a consequence, it appears imperative to understand the local drivers of coastal cliff erosion to assess the future consequences of climate change rather than applying general concepts for example in relation to erosion changes with increasing sea level rise. • Coastal cliff retreat must fit with wider scale Holocene coastal evolution. • Eemian chalk cliffs have been inactive up to a few hundred years ago. • Recent Chalk cliff retreat rates are less than 50% of the historic maximum. [ABSTRACT FROM AUTHOR]

Analysis of high-resolution seismic profiles integrated with archaeological data along the coast has allowed quantifying the last ∼10 ka BP displacements in the offshore part of the Campi Flegrei resurgent caldera, one of the world's highest-risk volcanic areas. Previous onland studies revealed that, following the Neapolitan Yellow Tuff (NYT) eruption at 15 ka, post-caldera evolution was associated with rapid ground uplift and subsidence cycles. In this paper, we use the stacking pattern of Prograding Wedges (PWs) and Aggrading Fills (AF) to reconstruct relative sea-level changes and estimate the amount of vertical deformation in the Pozzuoli Bay, the submerged part of the caldera. We document five generations of prograding wedges (PW1 to PW5), associated with as many periods of relative ground stability between uplift and subsidence. Instead, deposition of aggrading fills above prograding wedges underpins the subsidence that typically follows volcanic unrest and uplift. The older wedges PW1 and PW2 are larger and likely indicate whole-caldera uplift events. In particular, the development of PW2 starting from ∼5.2 ka is related to the rapid growth of a resurgent dome in the central part of the caldera. After ∼3.7 ka, subsidence prevailed in the caldera leading to deposition of an aggrading fill (AF2). However, subsidence was interrupted by short-term uplift episodes in historical times at (100 BCE-100 CE, 600–700 CE, 1430–1538 CE) that led to the growth of comparatively minor-sized wedges PW1 to PW3, respectively. Displacement of coastal infrastructures of the Roman age (∼2 ka BP) is consistent with the vertical motion retrieved by the seismostratigraphic analysis, and further indicates the existence of two deformation signals. A short-wavelength signal confined to the Pozzuoli Bay reflects the contribution of an intra-caldera source. This signal is superposed to a long-wavelength regional subsidence increasing between Naples and Procida Island from 1.5 to 2 mm/a, respectively. The east-to-west enhancing subsidence likely reflects the transition between the uplifting Apennines and the foundered Tyrrhenian back-arc basin. • High-resolution seismic profiles analysis in the offshore Campi Flegrei caldera • Seismostratigraphic bodies document relative sea-level changes • Quantitative reconstruction of vertical ground displacements in the Holocene • Roman-age coastal remains constrain ground deformation in the last 2 ka. • We disentangle the contribution of intra-caldera dynamics and regional tectonics. [ABSTRACT FROM AUTHOR]

Refined records of Holocene sea level and coastal evolution are needed to forecast changes in the Anthropocene. Beach ridge strandplains and other prograded barriers preserve an exceptional (and relatively untapped) archive of past sea level within their stratigraphy. Extracting these records using high-resolution geophysics can unearth sea-level indicators with the potential to resolve small fluctuations over large spatial- and temporal-scales. Brooke et al. (2019) construct a sea-level curve from Cowley strandplain and performs interesting modelling/analyses; but does so based on the beach ridge topography. Unfortunately, this methodological approach contradicts a long-held understanding that it is not appropriate to use ridge morphology or sediment analysis from cores/augers/pits to indicate sea level. This sets a misleading precedent if perpetuated in future research and does so at a critical time when extracting sea-level reconstructions from prograded barriers is becoming more established. While the Brooke et al. (2019) curve appears to correlate with data from this region, it is not precisely clear how it was constructed. Particularly perplexing is the most recent half of the curve, starting with the peculiar location of the modern analogue below mean sea level. Simply adjusting the existing curve to zero on the y-axis removes it from the tenuous correlation. This comment paper uses the geophysical and topographic data published in Brooke et al. (2019), as well as the protocol referenced, to construct relative sea-level curves. The results accentuate the difference between the reconstructions from the berm stratigraphy and the ridge morphology. Furthermore, despite the nature of this analysis utilizing a derivative dataset, the berm heights demonstrate remarkable correlation with the modelled sea-level curve for the region as well as the more traditional sea-level indicators. Ultimately, this glimpse provides insight on the possible extent of information that lies buried not just at Cowley and the 30+ prograded barriers around Australia, but at 300+ sites worldwide. • Elevation of Cowley beach ridges in LiDAR has no indicative meaning to sea level. • Re -analysis of berm elevation in the GPR reconstructs sea level over the past 3 ka. • Sea-level fall from ~1 m correlates with regional glacio-hydro-isostatic models. • Additional GPR can resolve the timing and elevation of a mid-Holocene highstand. • Using these methods on other strandplains can fill gaps in Global Sea Level Atlas. [ABSTRACT FROM AUTHOR]

The flux of low-salinity Pacific water (PW) through Bering Strait (BS) weights on the freshwater budget of the Arctic Ocean, which, in turn, impacts the Atlantic Meridional Overturning Circulation (AMOC). Through time, this PW flux has been tightly controlled by the bathymetry of the Strait (~50 m water depth at present), thus by sea-level (SL) changes, as documented in several papers based on a large array of sedimentological and geochemical tracers. The present study aimed at reassessing the robustness of these tracers of the PW-flux, based on five surface samples collected along a south–north transect from BS to the Chukchi Plateau, within the bathymetric range of the PW-mass dispersal. We also estimated their variation in relation to the post-glacial SL-rise in a sedimentary core (ARC4-R09), from the Chukchi shelf, spanning the last ~10 cal kyr. Potential indicators of PW-flux include sortable silt, clay minerals, and the particulate and exchangeable Nd-isotope composition of specific grain-size fractions. The results indicate that ɛNd-values in leachates, and to a lesser extent, the smectite abundance, both relating to volcanic rocks of the Bering Sea, are sensitive indicators of the PW-flux, whereas sortable silts and other clay minerals relative abundances are also influenced by other processes (e.g., west–east shelf currents, sea-ice rafting). The modern distributions of ɛNd-value and smectite abundance illustrate mixing between two endmembers: i) a northern Bering Sea endmember, characterized by ~14% of smectite (vs all clay minerals) and a ɛNd-value of the exchangeable fraction of ~ −2; ii) a Chukchi Sea endmember, characterized by ~8% of smectite and a ɛNd-value ranging from −7 to −8. The Holocene sedimentary record from the study core indicates a progressive increase in Bering Sea supplies through time, linked to an enhanced inflow of PW, which we associate with the deepening of the Strait due to the rising SL. Following a major reorganization of the Arctic Ocean circulation at ~8 cal kyr BP, a steady increase in PW flux prevailed until ~4 cal kyr BP. A tenuous but continuous positive trend towards modern εNd values followed during the late Holocene. The middle Holocene steep increase of warm, low salinity PW-flux through BS, led to important changes in the Arctic Ocean, in particular of its salinity budget. Assuming that the BS bathymetry is the main parameter governing the PW-flux towards the Arctic Ocean, a first-order estimate of PW-flux under a higher than modern SL can be made using the SL-elevation-ɛNd relationship of the major middle Holocene shift. • Assessment of the reliability of clay minerals and Nd-isotopes as tracers of PW-fluxes through Bering Strait. • Recording of Holocene PW-fluxes through Bering Strait by exchangeable ɛNd-values in a gravity core from the Chukchi Shelf. • Estimation of past changes in PW-fluxes towards the Arctic in relation with SL changes. [ABSTRACT FROM AUTHOR]

Abstract: Anthony et al. (2010) published a recent paper in Marine Geology on the origin and chronology of an inland dune for which they presented an explanation for the regional pattern of mid- to late Holocene coastal development. This explanation contradicts other data collected from this coastal area. It is moreover in contrast to our current understanding of Holocene coastal evolution of the Southern North Sea. The data used by Anthony et al. (2010) includes a number of inconsistencies that led the authors to incorrect conclusions. This discussion reports on our critical evaluation of data and reasoning in Antony et al. (2010). We propose an alternative model of coastal evolution which is in line with the current knowledge about mid- to late Holocene coastal evolution. [Copyright &y& Elsevier]

A high degree of uncertainty exists for understanding and predicting coastal estuarine response to changing climate, land-use, and sea-level conditions, leaving geologic records as a best-proxy for constraining potential outcomes. With the majority of the world's population focused in coastal regions, understanding how local systems respond to global, regional, and even local pressures is key in developing mitigation, adaptation, and management plans. The geomorphology of Mobile Bay in southeast Alabama (USA) has evolved considerably (e.g., bayhead delta back-stepping) over the late Holocene in response to global and regional sea-level and climate change. Smaller-scale geomorphic changes (e.g., spit and beach ridge development) have also had a significant influence on the evolution of the estuary. Organic matter characteristics, inorganic sediment geochemistry, benthic microfossils, and pollen in a ~ 3500 cal yr BP sediment sequence recovered in a gravity core (20GC) from Bon Secour Bay, a small sub-bay in the southeast corner of Mobile Bay, record time-varying marine influence. Increases in marine influence during ~3500 to 2300 cal yr BP and 1930 to 1160 cal yr BP are defined as zones with high-density and pre-dominantly calcareous foraminiferal species, abundant sand (>10%) and more marine-like geochemical signatures, which contrast the low-density and pre-dominantly agglutinated foraminiferal and more terrestrially influenced estuarine muds observed in other intervals of the sedimentary record (2300–1930 and 1160–400 cal yr BP) and the modern bay. Hydrodynamic models constrained by geomorphic boundary conditions for the time ~ 3500 cal yr BP, consistent with the most prominent marine-influenced sediment, provide insight to potential coastal configuration that might have permitted such marine water intrusion into the bay. Of several scenarios evaluated, a breach in Morgan Peninsula produces tidal circulation within the basin supportive of persistent marine incursions in the bay between ~3500 to 2300 cal yr BP. The findings show that slight variations in coastal configuration can have broad-scale effects on bays and estuaries with consequences that may relate to water quality, vertebrate and invertebrate habitat, and coastal vulnerability to episodic events like (extra)tropical storms. • Paleonenvironmental data identify frequent-to-periodic marine intrusions into Mobile/Bon Secour Bays over the past 3500 years. • Hydrodynamic modeling find that breaching of Morgan Peninsula is the likely explanation of early documented marine intrusions • Paper demonstrates the utility applying scenario-based model simulations to evaluate geologic and stratigraphic interpretations [ABSTRACT FROM AUTHOR]