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Geotechnical drilling for a tunnel between Port Moody and Burnaby, BC, Canada, uncovered a buried fjord. Its sedimentary fill has a thickness of at least 130 m and extends more than 37 m below present mean sea level. Recovered sediments record cyclical growth and decay of successive Cordilleran ice sheets. The oldest sediments comprise 58 m of almost stoneless silt conformably overlying ice-proximal sediments and till, which in turn overlie bedrock. These sediments may predate Marine Isotope Stage (MIS) 4. Glacial sediments assigned to MIS 4 overlie this basal succession and, in turn, are overlain by MIS 3 interstadial sediments and sediments from two MIS 2 glacial advances. Indicators of relative sea-level elevations that bracket glacial deposits of MIS 4 and 2 indicate the cyclic existence of moat-like isostatic depressions in the front of expanding ice sheets. Compared with present sea level, these depressions were at least 160 m during the onsets of MIS 4 and MIS 2. Assuming a maximum eustatic drawdown of 120 m during MIS 2, isostatic depression may have exceeded 200 m during retreat of glacial ice from the Evergreen tunnel area. This is consistent with region-specific low mantle viscosity and rapid Cordilleran Ice Sheet buildup and wasting. [ABSTRACT FROM AUTHOR]

The extent, chronology and dynamics of the pre‐Marine Isotope Stage (MIS) 2 last British–Irish Ice Sheet (BIIS) are not well known. Although the BRITICE‐CHRONO Project has detailed the maximum extent and retreat phases of the last BIIS for the period after 30 ka and into the Last Glacial Maximum (LGM), the Project identified several pre‐existing datasets and generated new data that implied glaciation pre‐dating the LGM but which post‐dated the Last Interglacial (Eemian; MIS5e); these data are reviewed here. There are no dated till units but are other indicators clearly indicative of glaciation: deep‐sea ice‐rafted detritus flux into the adjacent NE Atlantic, cosmogenic rock‐exposure age dating from glaciated surfaces in Wales and the island of Lundy (Bristol Channel), and optically stimulated luminescence (OSL) ages of proximal glacifluvial sequences on the Isle of Lewis (Outer Hebrides) and in the Cheshire Basin. Taken together these indicate BIIS inception during MIS5d, growth into MIS4 and evidence for dynamic retreat–advance phases during MIS3. OSL evidence for high relative sea level indicated by raised beaches in southern Ireland during MIS4 and 3 at a time of lowered glacio‐eustatic sea level indicates substantial glacial isostatic loading, explained by the early growth of the BIIS during the last cold stage. High relative sea level during MIS4 and 3 coincident with adjacent calving ice sheet margins provides an explanation for the rafted giant erratics found around the shores of southern Britain and Ireland. [ABSTRACT FROM AUTHOR]

The Lofoten and Vesterålen archipelagos are located off the outer coast of northern Norway far from the center of the former Fennoscandian Ice Sheet and near the continental shelf edge. Existing relative sea‐level (RSL) data indicate a pronounced mid‐Holocene transgression and interesting connections with the region's prehistoric human settlement history. Here we present seven new sea‐level index points from isolation basins and five terrestrial limiting points from a coastal sedimentary sequence to refine the region's RSL history. Ingression and isolation contacts in isolation basin sediment cores are identified using sedimentary geochemical data, scanning X‐ray fluorescence profiles and phytoplankton analysis. The ages of these contacts are determined using radiocarbon‐based age models. Our index points range from 11.2 to 1.5k cal a bp and are combined with previously published data to predict the spatiotemporal evolution of sea level in this region using an ensemble of spatiotemporal empirical hierarchical models (STEHME). The new RSL curve constrains the timing of the mid‐Holocene transgression, which occurred from c. 9 to 6k cal a bp when sea level increased from −4 to 7 m above present day. From c. 6 to 5k cal a bp, RSL rapidly fell to c. 4 m above present values, and more gradually declined at an average rate of c. 0.8 m ka−1 over the last 5k cal a bp. Isobase maps derived using the STEHME show a decrease in the regional shoreline gradients since the transgression maximum from 0.25 to 0.07 m km−1. Our data also better define how RSL variations influenced the location and preservation of coastal settlement locations and harbors from the early Stone Age through historic intervals, improving understanding of regional human–environment interactions. [ABSTRACT FROM AUTHOR]

A sediment core from the salt marsh fringing Loch Duart, NW Scotland, UK, containing Lateglacial to Holocene sediments, was analysed using a multi-element geochemical approach to elucidate the relative sea level (RSL) and palaeoenvironmental changes associated with the deglaciation of the British and Irish Ice Sheet. Elemental and isotopic measurements of rhenium, osmium, carbon and nitrogen, X-ray fluorescence scanning, radiocarbon dating, and foraminiferal analysis produced a suite of data that complements the existing biostratigraphic framework. This suite of bio-, litho- and chemostratigraphic analyses permits discussion of RSL changes that reflect the interplay between post-glacial eustatic rise and glacio-isostatic adjustment. The osmium-isotope (187Os/188Os) data, coupled with a new age-depth model, depict an RSL fall between 16.8 and 14.1 ka cal BP at an average rate of 2 mm a-1. Falling RSL culminates in basin isolation and is followed by subsequent marine inundation from 11.6 ka cal BP. This RSL record preserves the local interaction between glacial isostatic adjustment and glacio-eustatic sea-level change, a relationship that is reflected in the sediment's 187Os/188Os signature. This is the first known application of the osmium isotope system in an isolation basin that is shown to be a viable proxy for RSL change, a technique that could be applied to glacially influenced isolation basins globally. [ABSTRACT FROM AUTHOR]

Garrison, E.G., 2023. Sea-level evidence for a significant reduction of the Laurentide Ice Sheet in MIS 3, Georgia Bight, southeastern United States. Journal of Coastal Research, 39(5), 836–847. Charlotte (North Carolina), ISSN 0749-0208. Recently, a hypothesis was proposed for a significant reduction of the central region of the Laurentide Ice Sheet (LIS) from ca. 52 to 40 kYBP during marine isotope stage (MIS) 3. Corroborative evidence for this hypothesized reduction exists in the form of ages for higher sea levels in the Georgia Bight of the U.S. continental shelf, which have been dated to early MIS 3 using a variety of methods. These sea-level ages (15) were documented during ongoing continental shelf research conducted over the past two decades in the Georgia Bight and support the idea of a much-reduced LIS in early MIS 3 in synchrony with previously published geological and age data from the Hudson Bay Lowland of central Canada. The agreement between these data sets supports the need for a careful reassessment of late Pleistocene climate variability, ice retreat/advance, and a coupled sea-level response to both. This report reviews present and past research on paleoclimate in MIS 3 in order to place the age data in a broader perspective of sea-level and ice-volume drivers. Glacio-isostatic adjustment is also addressed as an important factor in near- and intermediate-field mantle response along the Atlantic coast of the United States to LIS ice loading during MIS 3. [ABSTRACT FROM AUTHOR]

This research assesses the impacts of climate change and relative sea level (RSL) fluctuations on coastal vegetation during the past 2000 years along the Mahanadi River delta, northeast coast of India. Sediment samples of a 2.6 m trench from Barhatubi area located in the lower flood plain of Mahanadi River delta were studied for sedimentological and pollen analysis. Mangrove succession can be divided into three zones: (1) Freshwater marsh (∼1980–1420 cal yr BP); (2) Tidal flat (∼1420–770 cal yr BP) and (3) Landward mangrove margin (∼770 cal yr BP-Present). A transgressive shift from floodplain freshwater marsh to a tidal flat is recorded between ∼1980–1420 cal yr BP which is evidenced by upland tree taxa, Poaceae, pteridophyte and fungal spores along with low percentage of mangroves such as Avicennia, Sonneratia and Rhizophora representing the landward edge of the tidal region. Dominance of Sonneratia and a decline in terrestrial taxa reflects a rise in the relative sea level around ∼1420 cal yr BP with less freshwater input from land suggesting a weakened monsoon condition. After ∼770 cal yr BP, an overall regressive phase with small cycles of relative sea level rise/fall has been observed due to the dominance of salt tolerant Avicennia along with Rhizophora, Excoecaria agallocha and Aegialitis rotundifolia alternating with Sonneratia and other marine palynomorphs. [ABSTRACT FROM AUTHOR]

We present an attempt to estimate the long-term changes in Relative Sea Level (RSL), in addition to the different factors contributing to such trends on a local and regional scale, using a statistical linear model. The time series analysis corresponded to 17 tide-gauges, grouped in three different areas: the northern and western Atlantic coasts of the Iberian Peninsula, the Canary Islands, and the southern and eastern coasts of the Iberian Peninsula and Balearic Islands. The analysis was performed for two periods: 1948–2019, using tide-gauge data; and 1993–2019, using both tide-gauge and altimetry data for comparison. The trends for the period 1948–2019 ranged between 1.09 ± 0.14 (Canary Islands) and 2.05 ± 0.21 mm/yr for the northern and western Atlantic Iberian Peninsula. Altimetry data during the period 1993–2019 yielded quite homogeneous results for all the locations and regions, ranging between 2.7 ± 0.4 and 3.0 ± 0.3 mm/yr. In contrast, the results obtained from tide-gauge data for this recent period showed a large dispersion, very likely due to local effects, or perhaps even to levelling or instrumental errors. Nevertheless, when the results were averaged for each area, the observed trends were comparable to the altimetry results, with values of 2.3 ± 0.8, 2.7 ± 0.5, and 2.8 ± 0.8 mm/yr for the three regions of study. A stepwise forward linear regression was used to relate the observed RSL variability to the atmospheric forcing and the thermosteric and halosteric components of the sea level. Surprisingly, the thermosteric and halosteric contributions were not significantly correlated to the observed RSL in many cases; consequently, the steric, the total addition of mass, the mass of salt, and the freshwater contributions to the observed sea level trends could not be reliably estimated. This result seems to have been the consequence of the scarcity of temperature and salinity data; this hypothesis was confirmed, with the exception of the tide-gauge data for L'Estartit. This location is close to a well sampled region. In this case, the atmospheric variables and the thermosteric and halosteric terms accounted for 80% of the observed RSL variance, and the contributions of these terms could be estimated. The freshwater contribution for this location was between 1.3 and 1.4 mm/yr, consistent with recent estimations of the contributions of glaciers and Greenland and Antarctica Ice Sheets. These results highlight the importance of monitoring programs and routine sampling for the determination of the different factors contributing to the sea level variability. [ABSTRACT FROM AUTHOR]

We demonstrate the utility and reproducibility of the saltmarsh foraminifera-based 'geological tide gauge' (GTG) approach by developing two independent records of relative sea-level (RSL) change for Dublin, Ireland. Our records, recovered from two different saltmarshes, indicate that RSL rose at a century-scale rate of 1.5 ± 0.9 mm yr-1 over the last 200 years. This compares favourably with the shorter, but more precise, mean sea level (MSL) record from the Dublin Port tide gauge, which indicates long-term (1953-2016 CE) rise at a rate of 1.1 ± 0.5 mm yr-1. When corrected for the influence of glacio-isostatic adjustment our saltmarsh-based reconstruction suggests sea levels in Dublin rose at a rate of 1.6 ± 0.9 mm yr-1 since the start of the 19th century, which is in excellent agreement with the regional value of MSL rise over the same period (1.5 ± 0.2 mm yr-1) calculated from a compilation of tide gauge records around Britain. Whilst our record has decadal-scale temporal resolution (1 sample every 8 years), we are currently unable to resolve multidecadal-scale variations in the rate of sea-level rise which are masked by the size of the vertical uncertainties (± 20 cm) associated with our reconstruction of palaeomarsh-surface elevation. We discuss the challenges of applying the GTG approach in the typically minerogenic saltmarshes of the NE Atlantic margin and outline potential solutions that would facilitate the production of Common Era RSL reconstructions in the region. [ABSTRACT FROM AUTHOR]

Since the 19th century, many scientists have tried to reconstruct the ground motions that occurred in the Campi Flegrei caldera, one of the most dangerous volcanos in the Mediterranean area. This study aims to assess the joint effects of vertical ground movements and anthropic forcing along the coasts of this volcanic area. A huge dataset of hundreds of archeo-stratigraphic boreholes was coupled with direct and indirect surveys of the main underwater archaeological sites scattered along the whole coastal sector and with the reinterpretation of bibliographic sources. Clear evidence of a differential volcano-tectonic behaviour (highlighted for the first time in this study) led us to divide the study area into three coastal stretches with homogeneous vertical ground movements. In each sector, a new relative sea-level (RSL) curve was reconstructed, by interpreting our stratigraphic and archaeological data in terms of SL markers covering a wider timespan compared to the previous studies, from the first Roman urbanization to the present day. The comparison between RSL curves and GIA models allowed estimating vertical ground movements (See Supplementary material 2) that occurred along the coast with decimetres accuracy. For each of the 5 recognized phase of uplift or subsidence, we also studied the subsequent effects in terms of coastal geomorphological change, and advantages or negative impacts on ancient human activities. We measured an overall subsiding trend that brought the RSL from −12 ± 1 m (4th century BC) to 7 ± 0.2 m during three different episodes between 5th and 15th centuries (1450–450 y BP) , which was interrupted by short-lived falls (less of 100 years) of RSL. During the phases of RSL fall and/or volcano-tectonic stability, detected for the first time in the eastern and western part of the caldera (1st-2nd century AD and 3rd-4th century AD), a basinward shift of the coastline created newly emerged land even at the base of the local sea cliffs, where shore platforms emerged, favouring intense phases of urbanization on them along the Baia – Miseno sector and at the footslope of Rione Terra. This trend also favoured the closure of the Lucrino lagoon with an extended spit bar during the 2nd century BC, allowing the establishment of a large oyster farming system belonging to Sergio Orata. On the contrary, the subsiding phases resulted in the flooding of coastal areas and anthropic structures such as villas, nymphaea and ports inducing the construction of coastal protection structures. In the extreme case of Portus Julius, subsidence led to the abandonment of the military port and its move to nearby Miseno. • Differential vertical ground movements in CF caldera during the last 2.4 ka. • Coastal changes due to the five reconstructed volcano-tectonics phases in 2.4 ka. • New relative sea level dataset of geological and geoarchaeological markers. • Statistical approach to the high-precision evaluation of historical VGM. [ABSTRACT FROM AUTHOR]

Luik, K.; Suursaar, Ü.; Tõnisson, H.; Rivis, R.; Suuroja, S., and Vilumaa, K., 2024. Millennia-long progradation turned into coastal erosion at Järve coast of the Baltic Sea. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 235-239. Charlotte (North Carolina), ISSN 0749-0208. Throughout the Holocene, seacoasts of the Baltic Sea have experienced some profound changes and development shifts. The latest one, the turn of the uplift driven progradation into relative sea level (RSL) rise and associated coastal erosion, is studied at the south-facing Järve coast on Saaremaa Island, Estonia. Old cartographic and photographic material, results from coastal surveys (near-annual since the 1990s), LiDAR-based relief analysis, and met-ocean forcing data are used to reveal important turning points, driving mechanisms, and resulted effects in the coastal change. The RSL lowering, which has dominated on account of the geocentric land uplift component (∼2.2 mm/a) during most of the Late-Holocene, has turned into RSL rise in the 1930s–1940s. Over the past hundred years, sea level maxima from storms and their impacts have increased due to a combination of shifts in wind climate and sea-ice conditions. The duration of seasonal ice-cover at the Järve coast, as an average, has decreased from about 65 days to 25 days. As a result, the elevated Järve coastal barrier and scarped dune system, which build-up took 4000 years, is eroding now on its southern side. The recent change at Järve has been especially fast with the most notable coastal erosion events occurring during winter storms. The coastline has receded by around 50–80 m in the past 70 years, and the scarp and previously wide beach is losing sand through longshore sediment drift towards the east. [ABSTRACT FROM AUTHOR]

• Raised beach is preserved at 3.3–5.3 m amsl in the upper Gulf of Thailand. • C14 and OSL age-dating suggest formation between 3.5–4.0 ka BP. • Provides evidence for Late Holocene local relative sea level (RSL) position. • Extends understanding of geographical variations in RSL across Southeast Asia. Few constructional features of coastal geomorphology have been investigated at the northernmost extremity of the Gulf of Thailand (GoT), with a view to establishing the position (height) of local relative sea level (RSL) during the marine regression following the regional mid-Holocene highstand (MHH) that occurred at approximately 6.5 ka BP. Here, the work investigates a 2 m thick exposure of marine gravels on the coast of Ko Khang Khao islet in the eastern Bay of Bangkok. At an elevation of 3.3–5.3 m above modern sea level, the sequence is interpreted to represent a Holocene raised beach. The unlithified sediments comprise rounded quartz and mylonite pebbles and cobbles, oriented predominantly NE–SW, supported by fossiliferous sands that are rich in marine shells, coral fragments and occasional terrestrial gastropods. The juxtaposition of the marine and non-marine gastropoda of contemporaneous ages makes a compelling story for a coastal storm deposit, thrown up either by a winter monsoon storm, or by a palaeotyphoon that managed to penetrate the upper Gulf. Overlapping results of C14 and OSL age-dating of shell material and mineral sands suggest the raised (storm) beach formed between 3.5 and 4.0 ka BP, i.e. ∼ 2.5–3.0 ka after the MHH peak, at a height of ∼ 1.3–3.3 m above the local RSL position at that time (according to glacial isostatic adjustment modelling). Given the otherwise paucity of data from the upper GoT, the Ko Khang Khao raised beach provides new information that expands our current understanding of geographical variations in RSL across Southeast Asia during the Late Holocene. [ABSTRACT FROM AUTHOR]

In this study, we examine the effect of transient mantle creep on the prediction of glacial isostatic adjustment (GIA) signals. Specifically, we compare predictions of relative sea level (RSL) change from GIA from a set of Earth models in which transient creep parameters are varied in a simple Burgers model to a reference case with a Maxwell viscoelastic rheology. The model predictions are evaluated in two ways: first, relative to each other to quantify the effect of parameter variation, and second, for their ability to reproduce well‐constrained sea level records from selected locations. Both the resolution and geographic location of the RSL observations determine whether the data can distinguish between model cases. Model predictions are most sensitive to the inclusion of transient mantle deformation in regions that are near‐field and peripheral relative to former ice sheets. This sensitivity appears particularly true along the North American west coast in the region of the former Cordilleran Ice Sheet, which experienced rapid sea‐level fall following deglaciation between 14 and 12 kyr BP. Relative to the Maxwell case, Burgers models better reproduce this rapid phase of regional postglacial sea‐level fall. As well, computed goodness‐of‐fit values in this region show a clear preference for models where transient deformation is present in the whole or lower mantle, and for models where the rigidity of the Kelvin element is weakened relative to the rigidity of the Maxwell element. In contrast, model predictions of relative sea‐level change in the far‐field show weak sensitivity to the inclusion of transient deformation. Plain Language Summary: In this study, we compare glacial isostatic adjustment (GIA) model predictions using two different Earth model types: Maxwell and Burgers models. Maxwell models are commonly used in GIA studies and employ a time‐invariant (steady‐state) form of mantle creep. Burgers models, on the other hand, allow for time‐varying mantle deformation and include both steady‐state and transient components of mantle creep. To evaluate the models, the predictions from both model types are compared to high quality records of relative sea level (RSL) change over the last several thousand years. Burgers models that include transient (time‐varying) mantle deformation often fit the RSL data as well as, or better, than the Maxwell models. In particular, the fit between predictions and data is improved in regions that were beneath or near former ice sheets, for example, along the west coast of North America. This result suggests that transient mantle deformation should be considered an additional process of interest in GIA models, especially in regions near the former ice sheets. Key Points: We compare glacial isostatic adjustment (GIA) model predictions with Maxwell and Burgers rheologies to relative sea level dataModels with Burgers rheology can yield better fits to sea level data, particularly around the west coast of North AmericaTransient deformation should be another process of interest in GIA models, especially in the near‐field [ABSTRACT FROM AUTHOR]

The Sibari Plain (northeastern Calabria) shows a well-developed stair of late Quaternary marine/coastal terraces resulting from the interaction between sea level fluctuations and tectonic uplift. This paper (i) provides a stratigraphic description of terraced deposits between the Raganello and Coscile rivers, (ii) assesses the relative controls of eustacy and uplift on the staircase formation, and (iii) unravels the Quaternary morphosedimentary evolution of the study area. A geomorphological approach was coupled with stratigraphic field surveys. Photo interpretation, topographic map analyses, and field surveys allowed us to map ten orders of terraces forming telescopically incised valley-fills. Based on the uppermost position of foreshore deposits on inner margins and an average uplift rate of ~1 mm/y, inferred from the Marine Isotope Stage (MIS) 5.5, terraces were correlated with highstands. Sedimentological and stratigraphic analyses allowed us to recognize four assemblages of genetically associated sedimentary facies related to superimposed and juxtaposed coastal and alluvial systems, showing a seaward-stepping architecture. Based on stratal geometry and facies association, we argue that alluvial/fluvial sediments and coastal depositional systems formed contemporaneously along the same terrace. Terrace arrangement resulted from repeated cycles of valley incision (sea level fall) and aggradational to progradational stacking pattern (sea level rise and highstands) in a framework of sustained uplift. [ABSTRACT FROM AUTHOR]

Beachrocks are well known as significant proxies for paleoenvironmental analysis as they indicate the coastal evolution. The combination of geomorphological and archaeological sea level indicators has a significant contribution to the coastal paleogeographic reconstruction. In this study, we studied a beachrock from the Diolkos area (West Corinth canal, Greece) and remnants of Diolkos slipway to reconstruct the coastal evolution before Diolkos construction until today. We conducted detailed mapping of Diolkos beachrock using DGPS-GNSS, as well as mineralogical analysis and OSL dating of beachrock samples. The results showed that a beachrock slab was preserved before the construction of Diolkos below it, followed by its submergence by a co-seismic event after Diolkos abandonment during 146 B.C. Consequently, a new beachrock was developed on top of the submerged Diolkos around 120 ± 14 A.D. The RSL was stable until 1596 ± 57 A.D. when the beachrock developed even closer to the present-day coastline. After 1596 A.D., it was uplifted by 12 cm until it reached today's condition. [ABSTRACT FROM AUTHOR]

We examined 14 subaerially deposited speleothems retrieved from submerged caves in the northeastern Yucatán Peninsula (Mexico). These speleothems grew during the Middle to Late Quaternary and were dated by 230Th‐U techniques to provide upper depth limits for past sea levels. We report the first relative sea‐level limits for Marine Isotope Stages (MIS) 11 and 6, and present new evidence for sea‐level oscillations during MIS 5 and early MIS 1. For the latter periods, the origin of growth interruptions is evaluated by combining petrographic methods with trace element analyses. The MIS 5c sea‐level highstand probably occurred between 103.94 ± 0.58 ka and 96.82 ± 0.42 ka and must have exceeded ‐10.8 m (relative to present‐day local sea level). The minimum average rate of sea‐level fall over a 9.4 ka‐long period during the MIS 5e/5d transition is calculated from stalagmite and published coral data at 1.74 ± 0.37 m/ka. For the early Holocene, previous discrepancies with respect to a potential multimetre oscillation of local sea level were found to be challenging to reconcile with the existing speleothem data from the area. [ABSTRACT FROM AUTHOR]

The impacts of relative sea‐level (RSL) variations and crust mobility on the development of ancient harbours in the northern Persian Gulf are poorly understood. Many unanswered questions remain with regard to the main reasons for a shift in the location of the most important ancient harbours in the northern part of the Persian Gulf coastal since 50 BC. Furthermore, some important early Islamic harbours, such as Siraf, have ancient city quarters that are today below the present sea level. The aim of this study is to evaluate the relationship between halokinesis and RSL changes using geophysical models and multidisciplinary geoarchaeological methods at the ancient Sassanid–Islamic site of Bataneh (presently known as Najirum) located at the foothill of an active Darang salt diapir. The results reveal that after the mid‐Holocene highstand, RSL regression was not continuous. The studied facies have recorded three RSL oscillations. The oscillations are correlated with the eustatic sea‐level position. During the first lowstand, important Sassanid harbours shifted from Rishar to Apologus. The second lowstand is consistent with the transition of maritime trade from Apologus to Siraf, during the Abbasid dynasty. Uplift of the Bataneh coastal zone exposed the city to risks from flooding and fluvial debris flows. With a modification of the local watershed, runoff water originating from the salt anticlinal was controlled and used for the extraction of gypsum in evaporation ponds. The economic expansion of Siraf led to Bataneh being abandoned with a shift in trade to Kish Island. [ABSTRACT FROM AUTHOR]

The sea and land change elevation spatially and temporally from a multitude of processes, so it is necessary to constrain the movement of both to evaluate how coastlines will evolve and how those evolving coastlines will impact the natural and built environment over time. We combine land movement observations from global navigation satellite systems (GNSSs), leveling of geodetic monuments, and tide gauge records with a tectonic model of the Cascadia subduction zone to constrain absolute rates of vertical land movement in coastal Washington. We infer rates of vertical land movement in areas lacking direct observations by interpolating high-quality land movement observations and a discretely sampled interseismic locking model. Here we present a model of absolute vertical land movement that is combined with sea level rise estimates to inform local relative sea level projections on a community-scale. The most rapid vertical uplift (~3.5 mm/year) of the land is found across the northwest Olympic Peninsula, which currently outpaces sea level rise. Conversely, some areas, including a stretch of the northern Pacific Ocean coast from La Push to Kalaloch and the southern Puget Sound, are found to be subsiding at 0.5–1.0 mm/year, exacerbating the rate of relative sea level rise and thereby increasing the vulnerability of coastal communities. [ABSTRACT FROM AUTHOR]

We collected contemporary foraminiferal training sets from two salt marshes to enable more precise and accurate proxy historical sea-level reconstructions from southeastern Australia. Combined with an existing training set from Tasmania, this new regional set consists of 112 samples and 16 species of foraminifera, of which 13 are agglutinated. Cluster analyses group the regional training set into a high-elevation cluster, dominated by Trochamminita salsa, a mid-elevation cluster, dominated by Entzia macrescens and Trochammina inflata, and a mid-low elevation cluster dominated by Miliammina fusca and tidal-flat species. We develop transfer functions using local and regional training sets and assess their performance. Our resulting site-specific and chosen regional models are capable of predicting sea level with decimetre-scale precision (95% confidence intervals of 0.12-0.22 m). These results are comparable to other examples from around the world. When developing regional training sets, we advocate that the similarity in the environmental settings (particularly salinity) should be assessed as an alternative way of grouping sites, rather than simply using spatial proximity. We compare our findings with global results and conclude that salt marshes along microtidal coasts yield models with the lowest vertical uncertainties. Studies with the lowest uncertainties are located in the western Pacific and the western Atlantic, whereas those from the eastern Atlantic generally have larger tidal ranges and carry larger vertical uncertainties. Our models expand the existing region available for sea-level reconstruction and can be used to generate new late Holocene sea-level reconstructions across southeastern Australia. [ABSTRACT FROM AUTHOR]

The Antarctic Ice Sheet (AIS) is the largest potential source for future global sea level rise. However, there are widely diverging estimates of its contribution, which emphasizes the need to improve our understanding of the long‐term behavior of the AIS and its impact on the solid Earth. This knowledge gap results from a shortage of records of glacial history, especially for the pre‐Holocene. Marine transgression and recession in the coastal areas of Antarctica are influenced by the mass of the overlying ice, providing crucial information about regional ice sheet dynamics. In this study, we determined a marine transgression from 53 kyr BP onward by diatom assemblages and a δ13C‐C/N biplot for the organic component in a sediment core (MCM2), from the Larsemann Hills in East Antarctica. Relative sea level (RSL) reached a maximum of ~12 m a.p.s.l. (above present sea level) during 38–29 kyr BP. Concurrent with the transgression, the regional crust experienced glacial‐isostatic‐adjustment (GIA)‐induced subsidence from ~75 to ~95 m beneath the present land level, suggesting an expansion trend of the East Antarctic ice sheet (EAIS), which may have outpaced global cooling. After the last deglaciation, the RSL rose to a highstand of ~8–10 m a.p.s.l. at ~8.5–7.1 kyr BP, when the bedrock uplifted to ~20 m below the present level. After 4.0 kyr BP, both regional and global deglaciation ceased, but an effect of ongoing relaxation caused the land to rebound continuously at a uniform rate of ~1.5 m/kyr, which can account for the sustained fall of RSL across Antarctica since mid‐Holocene. Key Points: A marine transgression period was constrained to 53–29 kyr BP at the Larsemann Hills, East AntarcticaWe provide a synthesis of the relative sea level changes and GIA‐induced displacement of the Larsemann Hills in the last 50 kyrThe ongoing relaxation process of GIA account for the sustained fall of the relative sea level since mid‐Holocene [ABSTRACT FROM AUTHOR]

Hampton Roads is among the regions along the U.S. Atlantic Coast experiencing high rates of relative sea level rise. Partly to mitigate subsidence from aquifer compaction, Hampton Roads is injecting treated wastewater into the underlying aquifer. However, the GPS (Global Positioning System) station spacing (∼30 km) is too coarse to capture the spatial variability of subsidence and potential uplift from the injection. We present a cost‐effective workflow for generating an InSAR (interferometric synthetic aperture radar) and GPS combined displacement product. We leverage a live, open‐access archive of InSAR products generated from Sentinel‐1 data. We find an overall subsidence rate of −3.6 ± 2.3 mm/year with considerable spatial variability. The effects of groundwater injection are currently below detection. The workflow presented here is an asset for sustained monitoring of the injection effort and regional subsidence that is applicable along the U.S. coasts for assisting in mitigation and adaptation of relative sea level rise. Plain Language Summary: Hampton Roads in coastal Virginia is among the regions experiencing high rates of relative sea level rise. This rate exceeds the global average primarily due to ongoing land subsidence. In part to reduce this subsidence, Hampton Roads has begun injecting treated wastewater into the underlying aquifer. However, the rate of subsidence and potential uplift from the injection is not uniform but varies spatially, such that the existing network of sensors is unsuitable for monitoring. Here we implement a cost‐effective approach for ongoing monitoring that leverages publicly available data products derived from the Sentinel‐1 satellite. Overall, we find that Hampton Roads is sinking at a rate of −3.6 ± 2.3 mm/year, with considerable differences at the neighborhood scale. The effects of the injection cannot yet be seen but will have a larger impact at the surface as more wastewater is injected at full‐scale facilities later this year. The workflow presented here is a valuable asset for sustained monitoring of the injection effort and regional subsidence that can be applied along the U.S. coasts for assisting in mitigation and adaptation of relative sea level rise. Key Points: SAR archive products are a cost‐effective means for subsidence mapping in support of coastal resilienceThe cities of Norfolk and Virginia Beach are subsiding at rates faster than 3.5 mm/yearThere is substantial spatial variability across Hampton Roads, VA, with hot spots of subsidence [ABSTRACT FROM AUTHOR]

The Paleocene hemipelagic deposits of the Dakhla Formation in Sinai offer an ideal setting to investigate paleoenvironmental fluctuations using benthic foraminifera. This study examined a Danian-Selandian sedimentary succession at Themed, Sinai using quantitative foraminiferal analysis within a sequence stratigraphic framework. Quantitative multivariate analyses, including R-mode clustering and non-metric multidimensional scaling (NMDS) ordination of biofacies trends and diversity parameters, indicate considerable paleoenvironmental and paleobathymetric changes throughout the studied succession. Five transgressive-regressive (T-R) sequences were identified based primarily on benthic foraminiferal biofacies trends. The sequence boundaries correlated well with major global sea-level lowstands. Benthic foraminiferal assemblages elucidated paleobathymetry fluctuations between upper bathyal and middle-outer neritic settings across the sequences. The identified sequences strongly correlate to global eustatic cycles, with subtle disparities suggesting a subordinate role for regional tectonics overprinting the dominant sea level control. The Latest Danian Event (LDE) interval coincides with the regressive phase of the fourth T-R sequence, as revealed from the biostratigraphic-constrained isotopic signature. It showed pronounced peaks in the relative abundance of the eutrophic buliminids, likely reflecting enhanced export productivity. Overall, benthic foraminifera provided vital paleoenvironmental insights, enabling sequence stratigraphic interpretation in the monotonous hemipelagites and highlighting possible coupled dynamics of both the carbon cycle and sea level. • Quantitative benthic foraminiferal biofacies enabled sequence stratigraphic interpretation. • Benthic foraminifera indicate fluctuations between bathyal and neritic settings. • Five transgressive-regressive 3rd order sequences were identified. • Sequences matched global eustatic cycles with slight regional tectonic overprinting. • Stressed benthic taxa indicative of perturbed conditions during the Latest Danian Event. [ABSTRACT FROM AUTHOR]

• Relative sea level rise from tide gauges along the Southern Levantine Basin (SLB). • Absolute sea level linear trends and variability over the SLB from satellite altimetry data during 1993–2015. • Vertical land motions from altimetry and tide gauge data along the SLB coastline with focus on Nile Delta region, Egypt. • Principal component analysis (PCA). We have investigated the sea level rise (SLR) in the Southern Levantine region of the Mediterranean Sea during the period 1993–2015 using satellite altimetry and tide gauge data. Satellite altimetry indicated a positive SLR with a mean of 3.51 ± 0.62 mm/year, which is slightly higher than the global averaged mean SLR that was reported about 3.19 ± 0.63 (Chambers et al., 2017). The rates of vertical land motion (VLM rate) have been estimated from the trend of de-seasoned sea level difference (altimetry minus TG) time series at the 6 selected TG sites. Land subsidence was found to occur at three stations along the Nile Delta coast (Rosetta, Burullus and Damietta) and at one station in Israel (Hadera). Most of the previous studies in the Mediterranean Sea indicated that there are no sufficient tide gauge data in the Southern and Eastern Mediterranean Sea. So, this investigation offers valuable sea level information that can be applied in a wide range of climatology, related environmental issues, for example; land subsidence, inundation, and global warming in the southern Levantine basin. [ABSTRACT FROM AUTHOR]

Abstract In spite of the recent advances and the current perspectives of satellite radar altimetry to reach the coastline and monitor coastal sea level changes, this space-borne technology remains geocentric by essence. In contrast, the quantity that matters for coastal management and society is relative sea level. That is, the sea level relative to the land, as measured by conventional tide gauges. However, two important issues are associated with the use of tide gauges. First, supplemental information is required to separate vertical land motion from ocean climate signals in tide gauge records, and hence to understand the causes of future coastal sea level changes and their relative importance. This can be provided by space-borne geodetic techniques, for instance installing a permanent Global Positioning System (GPS) antenna at the tide gauge. Second, vertical land motion can show local spatial patterns, which limits the spatial validity of the point-wise information at the GPS station. Using Interferometry Synthetic Aperture Radar (InSAR) and high-precision GPS data, the above-mentioned limitations were addressed in the case study of Brest (France). Our findings show that, over the past decades, Brest and its surroundings are overall stable, in agreement with the geological setting, except for the embankment areas of the commercial and military harbours. The GPS-calibrated InSAR results were then further combined with geocentric satellite radar altimetry data to obtain relative sea level trends along the Brest coastline with an unprecedented high-spatial resolution of 200 m. Our approach is applicable beyond the case study of Brest, especially in coastal areas where tide gauge data are not available, provided satellite data are. Highlights • GPS estimate of vertical land motion extended along Brest coastline using InSAR. • Evidence for an overall geodetically stable area at and around Brest tide gauge. • Subsidence is observed in recent reclaimed areas from the ocean (harbours). • Relative sea level trends along Brest coast from satellite altimetry and InSAR data. [ABSTRACT FROM AUTHOR]

Rocks formed in beach environments during the Holocene constitute strong evidences of relative sea level variations (RSL) and supply important data for paleoenvironmental reconstruction. At the southeastern Brazilian coast, an unusual association of lithofacies composed of hybrid carbonates and beachrocks was identified on the Parati beach in the Espírito Santo state. In this study, radiocarbon dating and sedimentary and geochemical characterization of five lithofacies were conducted, with the aim of reconstructing the paleoenvironmental conditions of deposition and cementation of this facies association. The lithofacies were classified as quartzarenites, bioclastic quartzarenites, hybrid carbonate and hybrid boundstones, with ages ranging from 2600 to 700 cal yr BP. Sedimentary and geochemical changes observed in these five lithofacies of the shallow shelf off southeastern Brazil reinforce evidence relative sea level variations during the Holocene. • Holocene carbonates occurrence on the Brazilian coast is evidence of mixed sedimentation. • The association of beachrocks and carbonates consists of a geological index. • This association shows relative sea level oscillations and climate change in the Late Holocene. • Geochemistry index associated with sedimentary structures are paleoenvironmental tools. • The understanding of coastal dynamics is fundamental for protection of the coastal population. [ABSTRACT FROM AUTHOR]

Hourly water level variations at Abu-Qir Bay were studied over 21 years. The levels were highly seasonal with a mean of 0.47m, and a rising rate of 6mm/yr. Tides are of semidiurnal type and of low amplitudes. No extreme sea level year was detected. Statistical analysis of surge heights was obtained. The estimation of flooding risks was determined. The design risk factor and return values of important water levels were calculated. An empirical relationship for the different water levels frequency of occurrence stated that the high water level of 3m might be exceeded once in 100 years. [ABSTRACT FROM AUTHOR]

Relative sea-level (RSL) reconstructions are essential to answer a variety of scientific questions, ranging from the investigation of crustal movements to the calibration of earth rheology models and ice sheet reconstructions. It is generally assumed that most Cycladic islands (Aegean Sea, Greece) are affected by a gradual subsidence, attributed to the crustal thinning and to hydro-isostatic processes that accompanied the post-glacial rise in sea level. In this paper, we produce new RSL data from sedimentary records on Paros Island. We compare and contrast these RSL data with published data from the nearby island of Naxos. Our results are further compared with sea-level predictions from two different GIA models in an attempt to better quantify the tectonic regime of the wider study area. Our results suggest average tectonic subsidence rates close to 1.0 ± 0.4 mm/yr since 5500 cal BP. These rates are not linear in time and have increased since 2500 cal BP. [ABSTRACT FROM AUTHOR]

Relative sea level history, which is the result of the combined effects of land subsidence, sediment supply and absolute sea level history may be reconstructed from preserved sediment thicknesses. However, variations in the preserved sediment thicknesses between different sedimentary environments strongly limit the accuracy of this type of geological approach, particularly in fluvial channelized systems, such as delta plains. To address this, we apply three different and independent stratigraphic approaches to the case of the Ganges–Brahmaputra–Meghna Delta (GBMD). Our approach has been made possible by a broad dataset of geological archives we have collected, which includes more than 400 hand-drilled stratigraphic wells, 198 radiocarbon ages, and river seismic reflection data (255 km of high-resolution multichannel seismic images). The seaward gradient of accommodation and the limit of the subsiding delta plain are estimated, assuming that the delta is near or at the base-level, which is considered to be the relative sea-level. First, a statistical analysis of the variability of preserved sediment thicknesses is used to derive the average pattern of accommodation from the Holocene isopach. Secondly, the preserved sediment thicknesses are analyzed by geomorphotectonic domains to estimate an average pattern of accommodation. Thirdly, the burial history of the seismically imaged last glacial incision of the Brahmaputra River is reconstructed. Results suggest that the variability of preserved sediment thicknesses can be up to 35% in a delta plain between river channel and flood plain deposits for the same relative sea-level history. Taking this variability into consideration, the Holocene relative sea-level history of the GBMD and the most likely pattern of subsidence are determined. Results provide evidence of moderate Holocene subsidence over the delta, gently increasing seaward from <0.2 mm/yr landward of the Hinge Zone, which can be considered as the northern limit of the subsiding delta plain, to 2 ± 0.7 mm/yr in the middle fluvial delta to 4 ± 1.4 mm/yr in the lower tidal delta. This enables us to construct the first millennial-scale map of subsidence pattern on the GBMD in which uncertainties on subsidence rates are provided. This map may aid in evaluating the negative impact that human modification may have on subsidence and relative sea level in the GBMD, and thereby help to determine better sustainable coastal management practices for the GBMD and other large delta plains. [ABSTRACT FROM AUTHOR]

Data from the recently drilled, fully cored Blokelv-1 borehole and previous cored boreholes in the Upper Jurassic of Jameson Land, central East Greenland, are integrated with published field studies to address the depositional evolution of the Jameson Land Basin in the Oxfordian--Volgian. In Jameson Land, the succession represents a marine shelf-to-basin transect in a W--SW-dipping half-graben. Laminated organic-rich mudstones were deposited in the central deep parts of the basin and grade up-slope into bioturbated sandy mudstones. Extensive shallow marine -- deltaic sand prograded from the western and northern basin margins and formed prominent sandy shelf-edge wedges. Sand-rich density flows initiated by periodic collapse of the shelf edge deposited massive sand bodies on the slope and basin floor; these sands were prone to post-burial remobilisation to form injectite bodies. Basin evolution was controlled both by relative sea-level changes, typically correlatable with regional and global sea-level curves, and by rift tectonics. During periods with high relative sea level, the organicrich muddy facies onlapped the sandy shelf environments; such periods of basinal expansion and onlap are recorded in the lower Oxfordian (Q. mariae Chronozone), the middle--upper Oxfordian (C. tenuiserratum -- A. glosense Chronozones) and uppermost Oxfordian -- upper Kimmeridgian (A. regulare -- A. autissiodorensis Chronozones); the deepening, transgressive trend culminated in the mid-Kimmeridgian (A. eudoxus Chron). Marked progradation of the sandy shelf and associated deposition of gravity-flow sands on the slope and basin floor occurred in the early Oxfordian (C. cordatum Chron), the middle Oxfordian (C. densiplicatum Chron), the late Oxfordian (A. serratum Chron) and the early Volgian (P. elegans Chron). The basin architecture reflects periodic differential subsidence on the W- to SW-dipping fault block. The lower to middle Oxfordian is highly condensed in the east (<10 m) and thickens markedly towards the west (>300 m), reflecting accumulation during rift/fault-controlled block rotation. The upper Oxfordian -- Kimmeridgian, in contrast, shows a broadly symmetrical distribution and records uniform regional subsidence. [ABSTRACT FROM AUTHOR]

Abstract High-quality relative sea-level (RSL) data reveal spatial and temporal variations in crustal movements during the Holocene, which are used for many applications, ranging from calibrating models of earth rheology and ice sheet reconstructions to the development of coastal lowlands and human occupation. Here, we present a Holocene RSL database for the Atlantic coast of Europe (ACE) and estimate rates of RSL change from the ACE database using a spatio-temporal empirical hierarchical model. The database contains 214 index points, which locate the RSL position in space and time, and 126 limiting dates, which constrain RSL to above or below a certain elevation at a specific point in time. The temporal distribution extends from present to ∼11.5 ka, with only 42 index points older than 7 ka. The spatial distribution spans 1700 km from French Flanders (France) to Algarve (Portugal), with more than half of the index points concentrated along the French coast. The ACE database shows RSL was below present during the Holocene. Rates of RSL change were highest during the early Holocene, ranging between 6.8 ± 0.5 mm yr−1 in middle Portugal and 6.3 ± 0.8 mm yr−1 in southern France from 10 to 7 ka. Mid-to late-Holocene rates decreased over time with rates ranging between 0.9 ± 0.4 mm yr−1 in middle France and 0.1 ± 0.5 mm yr−1 in middle Portugal from 4 ka to present. Comparison of the RSL data to output from a glacial-isostatic adjustment model suggests that deglaciation of the British-Irish and Fennoscandian Ice Sheets dominates the large-scale variability captured by the ACE database, which reflects a decreasing influence of the collapsing British-Irish and Fennoscandian peripheral forebulge that migrated from the northeast to the northwest after ∼4 ka. Highlights • A standardized Holocene relative sea-level (RSL) database from the Atlantic coast of Europe (ACE) is produced from sedimentary indicators. • RSL heights and rates of change are estimated from a spatio-temporal empirical hierarchical model. • RSL observations are compared to predictions from a glacial-isostatic adjustment (GIA) model. • Rates of RSL rise were highest (5.5–7.3 mm yr−1) in the early Holocene and decreased to <1 mm yr−1 after 7 ka, when meltwater input was reduced. • The spatial variability captured by the ACE database is most likely due to deglaciation of the British-Irish and Fennoscandian Ice Sheets. [ABSTRACT FROM AUTHOR]

The spatial variability of Holocene relative sea level (RSL) in the South China Sea is unknown, with data restricted to Thailand, the Malay Peninsula, and a few other isolated sites. In this study, we present new continuous RSL records for Borneo using surveyed and U-Th dated coral microatolls from four sites in western Sarawak. The record spans 450 years of RSL from 7450 to 7000 yr BP. Our data suggest that RSL was higher than present and rapid RSL rise had ceased by 7450 yr BP. We compare these RSL reconstructions with a regional model of glacial-isostatic adjustment (GIA). The RSL reconstructions from three sites off the coast of Sarawak show a spatial gradient opposite to that predicted by the GIA model. This disagreement can best be explained by tectonic deformation since 7000 yr BP, which was previously unrecognized. We propose vertical land motion of 0.7-1.45 m due to slip on the Serabang fault, which runs between our four sites. This slip may have occurred in response to the loading of the Sunda Shelf by rising sea level. [ABSTRACT FROM AUTHOR]

This paper concerns the relative sea-level changes associated with the Atlantic Patagonian coast derived from sea-level index points whose elevation was determined by a differential global position system (DGPS). Bioencrustations from outcrops located near Camarones, Chubut, Argentina, consist of autochthonous deposits characterized by Austromegabalanus psittacus (Molina, 1782), encrusting acervulinid foraminifera, coralline red algae and bryozoans. The association of the different organisms is interpreted as being associated with an intertidal environment, and they have been used as index points to establish the relative sea-level position. The main conclusion is that the relative sea-level between c. 7000 and 5300 cal. yr BP was in the range of c. 2-4 m a.s.l., with a mean value of c. 3.5 m a.s.l. Our data seem to support the existence of different rates of relative sea-level fall in different sectors of Atlantic Patagonia during the Holocene and highlight the importance of a more precise and accurate relative sea-level estimation by producing new data and revisiting the indicative meaning of most of the indicators so far used in the area. [ABSTRACT FROM AUTHOR]

ABSTRACT Providing a dense network of Holocene relative sea-level (RSL) records still faces some challenges, such as the paucity of microfossil assemblages within some Holocene sedimentary sequences. Recently, the isotopic (δ13C) and elemental geochemistry [total organic carbon (TOC), total nitrogen (TN) and C/N ratios] of saltmarsh sediments has showed potential for RSL reconstruction. This study presents the results of new δ13C, TOC and TN measurements obtained on surface sediments of two marshes of the Brittany region (France). Overall, the distribution of δ13C, TOC, TN and C/N values shows clear dependencies with elevation. Sediments from above and below the high tide level show contrasting TN contents. Clustering analyses identified three elevation-dependent groups, characterized by specific values of δ13C, TOC and TN. The use of this geochemical reference for RSL reconstruction is tested on a core retrieved from one of the marshes. The sea-level index points obtained plot in good accordance with the microfauna-based RSL positions previously obtained in the region. Some diagenetic losses in TN are observed between modern and Holocene sediments. This does not appear to be harmful to the accuracy of the RSL reconstructions but suggests that C/N ratios may be unreliable palaeoenvironmental proxies in this specific context. [ABSTRACT FROM AUTHOR]

ABSTRACT Accurate reconstruction of Lateglacial and Holocene relative sea-level (RSL) histories is complicated where mismatches exist between geological data and RSL curves generated by models of glacio-isostatic adjustment (GIA). In Ireland, such discrepancies have profound implications for interpreting the glacial history of the British Isles and for the use of glacial rebound models to predict future sea-level changes. To address this issue we present new RSL data from four sites along the western coast of Ireland, including 17 data points from the critical period before 5000 14C a BP for which very few data are available. We generate new RSL simulations from an existing GIA model, incorporating a thickened Irish Ice sheet component. Simulated curves from Co. Mayo and Co. Donegal accommodate the higher than present Lateglacial RSL inferred from glaciomarine muds while still meeting the requirement for below present RSL indicated by the new terrestrial limiting data points. Relaxation of trimline constraints on maximum ice sheet thickness provides considerable scope for improved GIA performance. These results demonstrate inferences about RSL drawn from GIA modelling and glacio-sedimentary data are not mutually exclusive, and represent a significant step towards resolving a long-standing debate between the field-based and modelling communities. [ABSTRACT FROM AUTHOR]

Relative sea level (RSL) changes and the palaeogeography of a Neolithic hunter-fisher-gatherer settlement site on the former shore of the Gulf of Finland in the city centre of Tallinn were reconstructed by implementing GIS in landscape modelling based on archaeological, sedimentary and shore displacement data. AMS radiocarbon dating of mammal bones from the cultural layer suggests the existence of the hunter-fisher-gatherer settlement around 5.1-4.8 cal. ka BP on a seaward inclining sandy beach of Tallinn palaeo-bay c. 100 m from the Litorina Sea shoreline and at about 2.4 m above the coeval sea level. The shoreline passed the study site at about 5.8 cal. ka BP and retreated towards northeast with an average speed of 13 m per century, while the RSL lowered byc. 2.5 mm annually. Combining radiocarbon dates of terrestrial and marine mammal bones from the Neolithic cultural layer, a marine reservoir effect of 350 14C years for the brackish-water Baltic Sea was calculated. By using high-resolution archaeological data in combination with RSL and other geological proxies, we demonstrate new possibilities to reconstruct the palaeoenvironment of deeply buried coastal settlement sites and to predict a possible continuation of the cultural layer in heavily built-up areas. [ABSTRACT FROM AUTHOR]

We present a high-resolution geochemical and grain-size record from a Holocene sediment core off the Pangani River mouth, Tanzania. Elemental ratios between biogenic elements and Al (i.e., Ca/Al, Mg/Al, and Sr/Al) are mainly influenced by terrigenous dilution on carbonate concentration and/or limitation of carbonate production as a result of variations in the supply of fine-grained terrigenous sediments of the Pangani River. Such elemental ratios increased significantly at the end of the mid-Holocene between 5 and 3.5 ka, demonstrating a gradual transition from the humid early and mid-Holocene to the arid late Holocene in East Africa. Among the elemental ratios between terrigenous elements and Al, Si/Al and K/Al ratios correlate to grain-size variation, indicating a change in sedimentation regime. Fe/Al and Ti/Al ratios show that the sediment source area has shifted from the terrestrial volcanic region of Tanzania (Fe, Ti rich) to the coastal and inner-shelf regions (Fe, Ti poor) around 7.5 ka, in response to arid climate and high sea level. Our geochemical results correspond with a sea-surface temperature record derived from the same sediment core, indicating that the end of the East African Humid Period could have been gradual and related to the cooling water in the western Indian Ocean. [ABSTRACT FROM AUTHOR]

Reconstructions of Holocene relative sea level (RSL) have valuable applications in a number of topics within the Earth sciences, including calibrating and constraining geophysical models of Earth’s rheology and glacial isostatic adjustment. The usefulness of these reconstructions depends on application of a standardized methodology that fully considers all age and vertical errors. We outline this methodology and provide a detailed example from New Jersey. We describe Holocene RSL reconstructions from the US Atlantic coast that illustrate both spatial and temporal variability. Spatially, rates of Holocene RSL rise were greatest in the Mid Atlantic (New Jersey and Delaware) with decreasing rates of rise to the north and south. Temporally, rates of RSL rise have decreased since the early Holocene due to the combined effects of continued relaxation of the solid Earth in response to deglaciation and reduction in ice melt since 7000 years ago. A comparison of late Holocene (last 4000 years) geological reconstructions to long-term tide-gauge measurements reveal that sea level rise increased above background rates by an average of 1.7 mm yr-1 during the twentieth century.

We present a Holocene relative sea-level (RSL) database for the Caribbean region (5°N to 25°N and 55°W to 90°W) that consists of 499 sea-level index points and 238 limiting dates. The database was compiled from multiple sea-level indicators (mangrove peat, microbial mats, beach rock and acroporid and massive corals). We subdivided the database into 20 regions to investigate the influence of tectonics and glacial isostatic adjustment on RSL. We account for the local-scale processes of sediment compaction and tidal range change using the stratigraphic position (overburden thickness) of index points and paleotidal modeling, respectively. We use a spatio-temporal empirical hierarchical model to estimate RSL position and its rates of change in the Caribbean over 1-ka time slices. Because of meltwater input, the rates of RSL change were highest during the early Holocene, with a maximum of 10.9 ± 0.6 m/ka in Suriname and Guyana and minimum of 7.4 ± 0.7 m/ka in south Florida from 12 to 8 ka. Following complete deglaciation of the Laurentide Ice Sheet (LIS) by ∼7 ka, mid-to late-Holocene rates slowed to < 2.4 ± 0.4 m/ka. The hierarchical model constrains the spatial extent of the mid-Holocene highstand. RSL did not exceed the present height during the Holocene, except on the northern coast of South America, where in Suriname and Guyana, RSL attained a height higher than present by 6.6 ka (82% probability). The highstand reached a maximum elevation of +1.0 ± 1.1 m between 5.3 and 5.2 ka. Regions with a highstand were located furthest away from the former LIS, where the effects from ocean syphoning and hydro-isostasy outweigh the influence of subsidence from forebulge collapse. [ABSTRACT FROM AUTHOR]

ABSTRACT We reconstruct one of the longest relative sea-level (RSL) records in north-west Europe from the north coast of mainland Scotland, using data collected from three sites in Loch Eriboll (Sutherland) that we combine with other studies from the region. Following deglaciation, RSL fell from a Lateglacial highstand of +6−8 m OD (Ordnance Datum = ca. mean sea level) at ca. 15 k cal a BP to below present, then rose to an early Holocene highstand and remained at ca. +1 m OD between ca. 7 and 3 k cal a BP, before falling to present. We find no evidence for significant differential Holocene glacio-isostatic adjustment between sites on the north-west (Lochinver, Loch Laxford), north (Loch Eriboll) and north-east (Wick) coast of mainland Scotland. This suggests that the region was rapidly deglaciated and there was little difference in ice loads across the region. From one site at the head of Loch Eriboll we report the most westerly sedimentary evidence for the early Holocene Storegga tsunami on the Scottish mainland. The presence of the Storegga tsunami in Loch Eriboll is predicted by a tsunami wave model, which suggests that the tsunami impacted the entire north coast of Scotland and probably also the Atlantic coastline of north-west Scotland. [ABSTRACT FROM AUTHOR]

Yoon, J.J., 2016. Analysis of long-period sea-level variation around the Korean Peninsula. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 1432 - 1436. Coconut Creek (Florida), ISSN 0749-0208. Regional long-term changes in sea level were investigated at 19 tidal stations located around the Korean Peninsula using more than 30 years of tide-gauge data. Regression analysis was applied to these data, and general trends of long-term change (1960-2014) in RSL (relative sea level) were estimated at each station. The results showed that the rates of RSL rise around Korea were higher than the global mean. Rates of RSL rise were relatively small along the western coast (average of 2.0 mm/yr.), large along the southern and eastern coasts (average of 2.8 and 3.6 mm/yr., respectively), and very large around Jeju Island (average of 3.8 mm/yr.). The rate of RSL rise near the coast of Jeju Island was about twice the world ocean mean. Interannual variations in sea-level rise around Korea showed regional differences. According to recently Fifth Assessment Report of IPCC, the rate of sea-level rise could accelerate throughout the 21st century. This should be considered when designing coastal structures in order to prevent coastal disasters. [ABSTRACT FROM AUTHOR]

Geomorphological and biological archives of relative sea-level change in the western North Atlantic-Caribbean region following the Last Glacial Maximum have traditionally supported the hypothesis of a punctuated rise towards the present sea level. Such records, however, are often at insufficient resolution to discern centennial-scale changes. In caves where the water table is closely controlled by sea level, active periods of speleothem growth constraining maximum sea level, used in combination with marine overgrowths constraining minimum sea level, are a promising alternative archive recording sea-level variability at higher resolution. Here, we present a U-Th-dated early–middle Holocene speleothem record from a submerged cave on the tectonically stable Yucatán Peninsula, Mexico. Our record shows that polychaetes (Annelida, Polychaeta) colonised a sub-aerially deposited stalagmite during four individual submergence events. Submergence events occurred at approximately 8.9, 8.6, 8.4 and 6.0 ka, which we attribute to previously unrecognised minor sea-level oscillation events (OE1–OE4) above and below −6.12 ± 0.1 m relative to present sea level (r.s.l.). Combining these results with mangrove-derived relative sea-level constraints from another submerged cave on the Yucatán Peninsula, we are able to suggest that OE1 and OE2 did not reach as high as −5.26 m r.s.l., but that OE3 and OE4 exceeded −5.22 m r.s.l. We conclude that subsidence of the North American ice-load bulge was the main cause of relative sea-level rise. Superimposed on the glacio-isostatic adjustment were periods of widespread northern hemisphere cooling and ice margin re-advance, resulting in a relative sea-level fall on four occasions during the early–middle Holocene. [ABSTRACT FROM AUTHOR]

This study provides new estimates of globally integrated ice sheet melt during the late Holocene (since 4 ka BP) from Seychelles in the western Indian Ocean, a tectonically stable, far field location where the necessary Glacial-Isostatic Adjustment (GIA) correction is small and is relatively insensitive to predictions using different Earth viscosity profiles. We compare sea level data from Seychelles to estimates of eustasy from two GIA models, ICE-5G and EUST3, which represent end-members in the quantity of global melt during the late Holocene. We use data from a range of coastal environments including fringing reef, present day beaches, fossil plateau and mangrove deposits on the largest island of the Seychelles archipelago, Mahé to reconstruct relative sea-level changes. Our data suggest that extensive coastal deposits of carbonate-rich sands that fringe the west coast formed in the last 2 ka and the horizontal nature of their surface topography suggests RSL stability during this period. Mangrove sediments preserved behind these deposits and in river mouths date to c. 2 ka and indicate that RSL was between −2 m and present during this interval. Correcting the reconstructed sea level data using a suite of optimal GIA models based on the two ice models mentioned above and a large number (c. 350) of Earth viscosity models gives a result that is consistent with the sedimentological constraints. When uncertainties in both model results and data are considered, it is possible to rule out eustatic sea levels below c. 2 m and more than a few decimetres above present during the past two millennia. This uncertainty is dominated by error in the reconstructions rather than the model predictions. We note, however, that our estimates of eustasy are more compatible with the EUST3 model compared to the ICE-5G model during the late Holocene (2–1 ka BP). Our evidence from Seychelles shows that the timing of when eustatic sea level first rose close to present is between the predictions of the two end-member GIA models presented here (4 ka BP for ICE-5G and 1 ka BP for EUST3). Using all lines of evidence currently available from Mahé we suggest that the eustatic contribution during the last 2 ka has been less than 2 m . This conclusion is drawn from a tectonically stable, far-field region that is relatively insensitive to earth and ice model uncertainties, and implies that global eustasy has been relatively insensitive to climate fluctuations over the pre-industrial part of the last 2 ka. [ABSTRACT FROM AUTHOR]

New records of paleoenvironmental change from two lakes near Cordova, south central Alaska, combined with analysis of previously reported sediment sequences from the adjacent Copper River Delta, provide quantitative constraints on a range of Earth system processes through their expression in relative sea-level change. Basal sediment ages from Upper Whitshed Lake indicate ice-free conditions by at least 14,140-15,040 cal yr BP. While Upper and Lower Whitshed Lakes provide only upper limits to relative sea-level change, interbedded layers of freshwater peat and intertidal silt extending more than 11 m below present sea level in Copper River Delta indicate net submergence over the last 6000 years and multiple earthquake deformation cycles. In contrast, Lower Whitshed Lake, situated just above present high tide level, records only one episode of marine sedimentation, commencing AD 1120-1500, that we interpret as the result of isostatic subsidence due to Little Ice Age mass accumulation of the Chugach Mountain glaciers. Lower Whitshed Lake also records isostatic uplift at the end of the Little Ice Age before the end of marine sedimentation caused by ~1.5 m coseismic uplift in the great Alaska earthquake of AD 1964. We successfully explain the records of relative sea-level change from both Copper River Delta and the Whitshed Lakes by integrating the effects of eustatic sea-level rise, glacial isostasy, earthquake deformation cycles, sediment loading, sediment compaction and Late Holocene changes in glacier mass into a single model. This approach provides initial quantitative constraints on the individual contributions of these processes. Taking reasonable estimates of eustasy, post-Last Glacial Maximum and Neoglacial glacial isostatic adjustment and a simple earthquake deformation cycle, we demonstrate that sediment loading and sediment compaction are both contributors to relative sea-level rise at Copper River Delta, together producing subsidence averaging approximately 1.2 mm yr-1 over the mid to Late Holocene. Further isolation basin studies have the potential to greatly improve our understanding of the individual contributions of these processes in this highly dynamic region. [ABSTRACT FROM AUTHOR]

The northern portion of the coastal plain of the Rio Grande do Sul State (southernmost Brazil) comprises an outer sandy barrier that protects a complex lagoon system formed during the Holocene. The terraces of three different lagoons (Gentil, Malvas and Pinguela) formed along their margins record the depositional processes and the relative base level changes over the past 5000 yr. Therefore, our main objective was to characterize and quantify base level fluctuations from the study of these terraces, to correlate them to sea-level changes and to describe the depositional architecture related to the distinct sea-level stages (high-resolution sequence stratigraphy). Satellite images, topographic and GPR profiles, auger holes and radiometric dating were used. The main results indicate a close relationship between relative base level and relative sea-level changes, a stillstand period just after the last transgressive maximum (4840–4650 cal yr BP) and a subsequent overall relative sea-level fall of about 3 m. Both a normal (highstand systems tract) and a forced regression (falling-stage systems tract) controlled the geological record preserved in the terraces. The highstand (older terrace) is characterized by agradational bedding, whereas the falling stage comprises three progradational sets (terraces) bounded by erosive surfaces related to smaller-scale sea-level drops. [ABSTRACT FROM AUTHOR]

Silva, J.B.; Duleba, W.; Sallun, A.M., and Suguio, K., 2014. Benthic foraminifera as evidence of paleoenvironmental changes between 9400 and 8300 cal YBP at the Juréia-Itatins Ecological Station paleolagoon (SP, Brasil). Many aspects of the Santos Transgression (∼21,227-20,448 to ∼5558-4558 cal YBP) remain controversial, especially before approximately 7800 cal YBP, because of the paucity of data for the Brazilian coast. In this context, benthic foraminiferal assemblages from between 9400 and 8385 cal YBP were analyzed from the S03 core collected at the Juréia-Itatins Ecological Station (JIES) with the aim of clarifying the behavior of the relative sea level along the Brazilian coast during this period. Microfaunal, taphonomical, and morphometric analyses of these microorganisms permitted recognition of eight paleoenvironmental conditions within the lagoon then existing at JIES. There were four phases of conspicuous marine contributions (9400-9338, 9072-8894, 8656-8641, and 8594-8500 cal YBP) with a climax at 8656 cal YBP, when the environment became more favorable to the growth, preservation, or both of benthic foraminifera. They were intercalated with two phases of prominent continental contributions (9338-9072 and 8500-8385 cal YBP), when there was an increase in the local hydrodynamic gradient at the S03 core sampling site. Furthermore, between 8806 and 8672 cal YBP and between 8625 and 8594 cal YBP, the benthic foraminifera are absent, most likely because of the lower pH of the mixohaline/limnetic waters present when the continental contribution was highest. These different phases of marine and continental contributions could be explained by the higher or lower inflow of seawater to the paleolagoon of the JIES and by changes of the regional rainfall. Muitos aspectos da Transgressão Santos (∼21.227-20.448 a ∼5558-4558 anos cal AP) são ainda controvertidos, especialmente antes de aproximadamente 7800 anos cal AP, devido à diferença de detalhamento de dados na costa brasileira. Nesse contexto, foram analisadas associações de foraminíferos bentônicos no testemunho S03, coletado na Estação Ecológica Juréia-Itatins (EEJI), entre 9400 e 8385 anos cal AP, para colaborar com o conhecimento acerca do nível relativo do mar na costa brasileira sudeste durante esse período. As análises microfaunísticas, tafonômicas, e morfométricas das testas e associações desses microorganismos permitiram a determinação de oito fases distintas nas condições paleoambientais na laguna então existente na EEJI. Houve quatro fases de contribuição oceânica mais conspícua (9400-9338, 9072-8894, 8656-8641, e 8594-8500 anos cal AP) com clímax há 8656 anos cal AP, quando o ambiente se tornou mais favorável ao crescimento, à preservação, ou ambos dos foraminíferos bentônicos. Elas foram entrecortadas por duas fases de contribuição continental proeminente (9338-9072 e 8500-8385 anos cal AP), quando houve aumento do gradiente hidrodinâmico local no local de coleta do testemunho S03. Além disso, entre 8806 e 8672 anos cal AP e entre 8625 e 8594 anos cal AP, os foraminíferos bentônicos estiveram ausentes, muito provavelmente devido ao menor pH das águas oligohalinas/limnéticas presentes quando a contribuição continental à paleolagoa da EEJI foi maior. Essas diferentes contribuições podem estar vinculadas a modificações da pluviosidade regional e a diferenças no comportamento marinho durante sua fase transgressiva. [ABSTRACT FROM AUTHOR]

ABSTRACT A new sea-level record derived from coastal deposits of the South Vietnam shelf covers the deglacial sea-level history between 13.0 and 9.0 ka BP. This record reveals a relatively constant rate of sea-level rise and matches well with model results based on the RSES-ANU global ice-sheet model. However, the sea-level observations reveal a significant discrepancy with model results based on the ICE-5G global ice-sheet model, which further questions the existence of Meltwater Pulse 1B The incised-valley deposits of the South Vietnam shelf also complete the deglacial coastal evolution of southern Vietnam. The regional sea-level records of the South Vietnam shelf, the Mekong Delta and the Cambodian lowlands reveal an offset of about 18 m between 9.0 and 8.2 ka BP. The shoreline retreat of more than 200 km related to this offset was mainly caused by the differential hydro-isostatic adjustment between the South Vietnam shelf and the Cambodian lowlands. However, the GIA-model results cannot fully explain this fast relative sea-level rise due to the topographic changes and, possibly, alternative melt-water sources not accounted for in the current models. [ABSTRACT FROM AUTHOR]