Coastal Landscape Evolution Research Articles

On the shoreline monitoring via earth observation: An isoradiometric method

Shoreline variations, triggered by climate change, eustatism, and tectonic, drive the coastal landscape evolution over multiple spatial and temporal scales. Among the many different existing coast types, sandy coasts are the most sensitive to coastal erosion and accretion processes and, at the same time, often host valuable anthropogenic assets. The rapid and ongoing evolution of these coastal environments poses challenges for their management, necessitating cost-effective and highly reliable methods for measuring these changes. Many remotely sensed shoreline extraction methods have been proposed in the literature, providing valuable tools for improving coastal management. Even if these methodologies allow the demarcation of the shoreline, its pixelated shape usually requires refinement through subsequent smoothing or vector generalization processes. It is important to note that the position of the thus extracted coastline is not a direct result of a measured physical quantity but rather a product of these refinement techniques. To address this problem, we developed a sub-pixel resolution method for extracting shorelines from remotely sensed images of sandy beaches, leveraging the radiometric signature of the shoreline. Validated through precise Global Navigation Satellite System field surveys for positioning the beach foreshore, this method was successfully applied to three beaches in Sicily, in the central Mediterranean, all exhibiting similar microtidal conditions. Its robust design allows for application across various satellite images, employing a straightforward radiometric interpolation method adaptable to different spatial resolutions. This method would be a valuable tool for coastal managers in detecting and mitigating coastal erosion and developing and maintaining anthropogenic coastal assets.

A city against the current: A reconstruction of Holocene sea-level changes and the evolution of coastal landscapes in ancient Abdera (Thrace, Gr.)

This paper presents an integrated Geoarchaeological approach to Holocene landscape change and socio-environmental interaction around ancient Abdera, a Greek colony in Aegean Thrace. A combination of remote sensing, geomorphological mapping, sedimentary coring, and radiocarbon dating was used to build the first detailed Holocene sea-level curve in the Northern Aegean, and to reconstruct the palaeogeographic evolution around Abdera from the Neolithic onwards. The discussion of these results, alongside the available archaeo-historical data, sheds new light on the role of historical and environmental factors in the rise and eventual decline of Abdera, thereby challenging previous narratives. This study is the first to detect evidence of the Neolithic landscapes in this coastal area being submerged by marine transgression c. 5000 cal. BC. A lagoonal landscape developed from the Neolithic until Greek colonists settled in the area c. 654 BC. The results presented here suggest that the relocation of the city in the 4th century BC was not caused by the silting up of the bay but was due to historical events. The coastal progradation only became significant after 300 cal. BC and accelerated in the following centuries. Based on the data acquired, it is hypothesized that this was due to anthropogenic forcing of the sedimentary systems both at local and regional levels, caused by the development of the productive activities of the colony. The evidence presented here demonstrates that while Abdera retained good access to the sea, its decline in the 4th c. AD was certainly due to the gradual shift of the economic axis inland. By 400 cal. AD the coastline was very close to its current position. The results of this study also add to the catalogue of known tsunamis in the Northern Aegean, by providing new evidence of a tsunami on this section of the Thracian coast in 544 AD.

Understanding the landscape evolution of El Mogote barrier spit, Baja California Sur, Mexico, using OSL dating, satellite images and a multivariate analysis

Barrier spits are natural archives that provide information about coastal evolution and prevailing environmental conditions of the mainland. In this study, we analyze one of the largest barrier spits in Baja California Sur, Mexico, known as El Mogote bar, using a multi-method approach to unravel the coastal landscape evolution. We used (1) OSL dating to provide a robust geochronology and depositional rates of the emerged beach-dune ridges, (2) satellite imagery interpretation using the Digital Shoreline Analysis System (DSAS) software to assess shoreline changes on Landsat images from 1986 to 2014, and (3) the Principal Component Analysis (PCA) with climatic and geomorphologic parameters to elucidate the environmental conditions of the beach-dune ridges for the period comprised in the DSAS analysis. OSL results indicate that the emerged bars started to form ∼2 ka and were developed in three main building phases: (1) the Medieval Warm Period (MWP) and part of the Little Ice Age (LIA) with accretional rates of 1.13 m yr −1, (2) the ending of the LIA with 7.03 m yr −1 and (3) the post-LIA with 3.98 m yr −1. In this paper, we hypothesize two probable causes that led to the destruction of the former beach-dune ridges: (1) tsunami waves triggered by seismic events and (2) local sea level rise associated with local tectonic subsidence. Satellite images and DSAS analysis show that, in the barrier spit, accretion and erosion have been in dynamic equilibrium for at least three decades. PCA results indicate that dry and cold weather conditions, El Niño modes, and tropical cyclone occurrence with high accretional rates on the barrier spit are the main controls on the beach-dune ridges. We conclude that the multi-method approach used in this research is suitable to tease out the landscape evolution of a barrier spit from a climatic and geomorphological perspective, as we were able to identify that the accretional episodes of El Mogote bar are mainly related to rainfall during the coldest and driest environmental conditions that enhance sediment supply from continental areas to the coast.

Extremely fast Holocene coastal landscape evolution in the Kachchh Upland (NW India): Clues from a multidisciplinary review

ABSTRACT The coastal landscape of the Kachchh Upland (KU) region (NW-India) changed over the last few thousand years from a shallow marine gulf to a salty desert (1-4 meters asl). In this area, bordered to the south by the Northern Hill Range (NHR), the tectonic-climatic interaction triggered the sea level fall from +2/4 m circa (6000-2000 BP) to zero. An ancient river pattern deposited a tidally regulated delta area during the sea level fall that stopped 2000-3000 years ago due to tectonic activity and a dry climate. Deltaic-alluvial fans (DAF) in front of the NHR suggest that the KU's tectonic activity led to fast landscape evolution. We explored such drastic changes by integrating scientific information from a multidisciplinary literature review, identifying terraces and DAFs, and inferring faults through landform recognition, quantitative morphometry, and field surveys. Our interpretation, summarized in a map, provides new information on active processes along the NHR.

InSAR-derived surface deformation of Chaoshan Plain, China: Exploring the role of human activities in the evolution of coastal landscapes

Understanding the characteristics of different human-induced coastal surface deformation will improve our understanding of recent temporal-spatial evolution trends of the coastal terrain, and help better predict the risks of coastal disasters. However, few surface deformation studies have focused on the distinction between different types of anthropogenic ground deformation. Based on Sentinel-1 Synthetic Aperture Radar (SAR) data, this study employs the hybrid multi-temporal Interferometric Synthetic Aperture Radar (InSAR) method to extract the surface deformation of Chaoshan Plain from 2015 to 2020, with a spatial resolution of 30 m × 30 m. A series of historical optical satellite images and groundwater extraction data are used to help distinguish different types of human activities that have induced surface deformation. The characteristics of ground deformation induced by different types of anthropogenic activities are explored in the space and time dimensions. Results show that InSAR ground deformation in the study area is mainly caused by three types of human activities: groundwater extraction, land reclamation, and construction. Groundwater extraction has impacted >50% of the regional surface deformation by area. The interannual variability of the surface deformation rate corresponds well to that of groundwater extraction, and the subsidence effect can last for more than five years with seasonal variability. The maximum surface subsidence rate in land reclamation areas reaches ~100 mm/year, with a linear decreasing trend against time. Without extra compaction, the reclamation area can continue to deform almost at the same rate for several years. The rapid increase of overlying loads caused by construction in the reclamation area has led to a sharp decrease in the deformation rate within 2–3 years after the completion of the construction. In areas absent of other human-induced deformation, construction activities are shown to cause surface subsidence of 10–20 mm/year in a relatively short period. In areas experiencing a combination of construction and groundwater extraction, land subsidence rates of >50 mm/year are observed. This study shows that the spatial and temporal analysis of the correlations between human activities and InSAR surface deformation is an effective way to attribute the driven factors of coastal plain deformation.

Plio-Quaternary coastal landscape evolution of north-western Sicily (Italy)

ABSTRACT We present and discuss the results of a geomorphological and geological study aimed at reconstructing the Plio-Quaternary evolution of the NW Sicily coastal belt , a low strain rate region in the central Mediterranean Sea. We performed morphometric and field analysis of Quaternary marine terraces extracting more than 300 shoreline location points subdivided into six orders. The obtained dataset was validate by investigating the morphological changes along topographic profiles and comparing the extracted locations and elevations with the stratigraphic boundaries in the Plio-Quaternary units. We distinguished two contiguous coastal sectors characterized by different paleo-shoreline elevations and Plio-Quaternary evolution, whose estimated uplift rates fit well with the well-known, regional eastward uplift rate increase along the Northern Sicilian continental margin. Obtained results, summarized in a geomorphological map and a morpho-evolutionary model, provide new valuable data to characterize the active deformation processes and the seismotectonic setting in this critical sector of the Africa-Europe plate boundary.

Vegetation and peat accumulation steer Holocene tidal–fluvial basin filling and overbank sedimentation along the Old Rhine River, The Netherlands

AbstractIn the transformation from tidal systems to freshwater coastal landscapes, plants act as eco‐engineering species that reduce hydrodynamics and trap sediment, but nature and timing of the mechanisms of land creation along estuaries remains unclear. This article focuses on the Old Rhine estuary (The Netherlands) to show the importance of vegetation in coastal landscape evolution, predominantly regarding tidal basin filling and overbank morphology. This estuary hosted the main outflow channel of the river Rhine between ca 6500 to 2000 cal bp, and was constrained by peat during most of its existence. This study reconstructs its geological evolution, by correlating newly integrated geological data and new field records to varying conditions. Numerical modelling was performed to test the inferred mechanisms. It was found that floodbasin vegetation and resulting organic accumulation strongly accelerated back‐barrier infill, by minimizing tidal influence. After tidal and wave transport had already sufficiently filled the back‐barrier basin, reed rapidly expanded from its edges under brackish conditions, as shown by diatom analysis and datings. Reed growth provided a positive infilling feedback by reducing tidal flow and tidal prism, accelerating basin infilling. New radiocarbon dates show that large‐scale crevassing along the Old Rhine River – driven by tidal backwater effect – only started as nutrient‐rich river water transformed the floodbasin into an Alder carr in a next phase of estuary evolution. Such less dense vegetation promotes crevassing as sediments are more easily transported into the floodbasin. As river discharge increased and estuary mouth infilling progressed, crevasse activity diminished around 3800 to 3000 cal bp, likely due to a reduced tidal backwater effect. The insights from this data‐rich Holocene study showcase the dominant role that vegetation may have in the long‐term evolution of coastal wetlands. It provides clues for effective use of vegetation in vulnerable wetland landscapes to steer sedimentation patterns to strategically adapt to rising water levels.

A phenology- and trend-based approach for accurate mapping of sea-level driven coastal forest retreat

The rapid replacement of upland forest by encroaching marshland is a striking manifestation of global sea-level rise (SLR). Timely and high-resolution information on the location and extent of transition forest (the ecotone between upland forest and marsh where tree mortality due to seawater intrusion begins) is fundamental to understanding the processes and patterns of SLR-driven landscape reorganization. Despite its significance, accurate characterization of salt-impacted transition forest remains challenging due to the complexity of coastal environments, scarcity of ground-truth data, and the lack of effective mapping algorithms. Here we use the full archive of Landsat images between 1984 and 2021 to investigate the spectral, temporal, and phenological characteristics of transition forest, and develop a robust framework for monitoring coastal vegetation shifts in the mid-Atlantic U.S., a global SLR hotspot. We found that transition forest exhibits strong negative NDVI trends and a deviation of land surface phenology from marsh and upland forest that distinguishes itself from surrounding vegetation. By integrating temporal trends and land surface phenology, our results demonstrate superior discrimination between marsh and coastal forests to existing map products (e.g. NOAA Coastal Change Analysis Program, National Land Cover Database) that allows a reliable identification of the coastal treeline. We applied the approach to map regional land cover in 1985, 2000 and 2020 (overall classification accuracy >92%) and found that the area of coastal forest decreased by 22.0% from 1985 to 2020, the majority of which transitioned to marshland (92.3%, 5.3 × 103 ha). Based upon fine-scale patterns of coastal transgression, we created a practical workflow for spatially explicit quantification of forest retreat rates. Concurrent with rising sea level, coastal forests migrated upslope from 0.63 (± 0.27) m above sea level in 1985 to 0.78 (± 0.32) m above sea level in 2020, and horizontal forest retreat rates accelerated from 3.1 (range of 0–36) m yr−1 during 1985–2000 to 4.7 (0–55) m yr−1 during 2001–2020. As SLR continues to accelerate, our study may serve as a scalable solution for consistent tracking of coastal landscape evolution that is urgently needed for sustainable forest and wetland management.

Impact of Coastal Marsh Eco‐Geomorphologic Change on Saltwater Intrusion Under Future Sea Level Rise

AbstractCoastal saltwater intrusion (SWI) is one key factor that affects the hydrology, ecology, and biogeochemistry of coastal ecosystems. Future climate change, especially intensified sea level rise (SLR), is expected to trigger SWI to encroach on coastal freshwater aquifers more intensively. Numerous studies have investigated decadal/century scale SWI under SLR by assuming a static coastal landscape topography. However, coastal landscapes are highly dynamic in response to SLR, and the impact of coastal landscape evolution on SWI has received very little attention. Thus, this study used a coastal marsh landscape as an example and investigated how coastal marsh evolution affects future SWI with a physically‐based coastal hydro‐eco‐geomorphologic model, Advanced Terrestrial Simulator. Our numerical experiments showed that it is very likely that the marsh elevation increases with future SLR due to sediment deposition, and a depression zone is formed due to different marsh accretion rates between the ocean boundary and the inland. We found that marsh accretion may significantly reduce the surface saltwater inflow at the ocean boundary, and the evolved topographic depression zone may prolong the residence time of surface ponded saltwater, affecting subsurface salinity distribution differently. We also predicted that marshlands may become more sensitive to upland freshwater supply under future SLR, compared with previous predictions without marsh evolution. This study demonstrates the importance of coastal evolution to coastal freshwater‐saltwater interaction. The eco‐geomorphologic effect may not be ignored when evaluating coastal SWI under SLR at decadal or century scales.

Soil-chronosequence and Quaternary landscape evolution at the marine terraces of Harmony Point, Nelson Island, Maritime Antarctica.

This study characterized the physical, chemical, macro- and micromorphological soil properties from three successive marine terrace levels from Harmony Point (Nelson Island, Maritime Antarctica) in order to understand the pedological signatures of Quaternary coastal landscape evolution of Maritime Antarctica. Soils were sampled on the Late Holocene beach (current beach) and Mid Holocene marine terraces higher up, at 3, 8, and 12 m a.s.l. At the lower levels, the predominant soils were Gelorthents, whereas Haplogelepts dominate the higher terraces. Soil properties are mostly influenced by parent material and faunal activity, in which cryoclastic (thermal weathering) and phosphatization are the main soil-forming processes. Soils from the upper levels are more developed, deeper with reddish colors, granular structures and incipient formation B horizon. These horizonation features highlight that soils vary according with age of glacier-isostatic terrace uplift, representing a Quaternary soil chronosequence. All marine terrace levels are Ornithogenic soils, at varying degrees. However, the presence of old bird nesting sites for long periods led to formation of phosphatic horizons, stable Fe-phosphate minerals and abundant vegetation in the highest terraces of this part of Maritime Antarctica.

Quaternary Coastal Landscape Evolution and Sea-Level Rise: An Example from South-East Sicily

Coastal depositional environments are the site of complex interactions between continental and marine processes. Barrier islands are highly dynamic coastal systems, typical of these transitional environments, and are affected by sea level changes and the accumulation of transgressive deposits with the landwards migration of the coast. The offshore of Marzamemi (Syracuse Province, Sicily), in the south-eastern portion of the Hyblean foreland, represents an excellent site for the study of transgressive deposits and their connection with the sea-level changes. The available dataset consisted of new high-resolution bathymetry (Multibeam), whose description and interpretation through a Digital Elevation Model (DEM) was integrated with a grid of eighteen seismic profiles (SPARKER). In the investigated bathymetric range, from about −5 m to −60 m, a sensibly different morphological setting between the northern and southern sectors was evident. Within the whole study area, three bathymetric contours (−45 m, −35 m and −20 m) were identified and assumed as the markers of the main locations of the paleo-coastlines during the recent changes in the sea level. Along the northern sector, three submerged barrier-lagoon systems developed on a calcarenite substratum, marking important steps of the Late Quaternary sea-level rise. They coexisted with numerous karst forms (poljes and dolines). In the southern sector the transgressive environmental evolution was significantly different and submerged lagoons did not form. Here the outcropping calcarenite substratum was affected by the development of paleo-rivers and karsts structures, a tract in common along with many Mediterranean carbonate coastal areas.

Integrating Geomorphological Data, Geochronology and Archaeological Evidence for Coastal Landscape Reconstruction, the Case of Ammoudara Beach, Crete

Understanding the processes that govern the transformation of the landscape through time is essential for exploring the evolution of a coastal area. Coastal landscapes are dynamic sites, with their evolution strongly linked with waves and sea level variations. Geomorphological features in the coastal area, such as beachrock formations and dune fields, can function as indicators of the coastal landscape evolution through time. However, our knowledge of the chronological framework of coastal deposits in the Aegean coasts is limited. Optically Stimulated Luminescence dating techniques are deemed to be very promising in direct dating of the coastal sediments, especially when they are linked with archaeological evidence. The dating of the sediments from different sediment core depths, determined by the method of luminosity, allowed us to calculate the rate of sediment deposition over time. More recent coastal evolution and stability were examined from 1945 to 2020 with the use of aerial photographs and satellite images. This paper presents the 6000 ka evolution of a coastal landscape based on geomorphological, archaeological, and radio-chronological data. Based on the results, the early stages of the Ammoudara beach dune field appears to have been formed ~9.0–9.6 ka BP, while the OSL ages from 6 m depth represented the timing of its stabilization (OSL ages ~5–6 ka). This indicates that the dune field appears to already have been formed long before the Bronze Age (5–10 ka BP). It became stabilized with only localized episodes of dune reactivation occurring. In contrast, while high coastal erosion rates were calculated for modern times.

Palaeoenvironmental and sea level changes during the Holocene in eastern Saudi Arabia and their implications for Neolithic populations

This paper presents the key findings of a multidisciplinary study investigating the nature and timing of coastal landscape evolution in eastern Saudi Arabia during the Holocene. To date, most sea level reconstructions for the Arabo-Persian Gulf are based on uncalibrated 14C ages without correction for marine reservoir effects, or lack precision with regard to the effects of neotectonic changes, indicators of sea level used, errors in elevation of sedimentary units used, and the relationship with actual tides. As a consequence, the nature and timing of relative sea level (RSL) changes during the Late Pleistocene and Holocene remain poorly understood. To help address this, we use sea level index points (SLIPs) based on calibrated 14C ages to present a RSL curve for the central-southern Gulf of Saudi Arabia from coastal sabkha deposits near the archaeological site of Dosariyah. The sediments record rapid transgression during the early Holocene with a mid-Holocene high-stand immediately prior to 6880–6560 cal. BP when the upper limit for the palaeo Mean Highest High tide water (MHHW) was 2.8–3.10 m above present day mean sea level. Transgression continued until shortly after 5575–5310 cal. BP with an upper limit to the palaeo-MHHW of 3.75 m above present sea levels. Thereafter a fall in RSL was recorded, with the regression leading to the progradation of the coastal system and the development of coastal sabkhas. Nonetheless later transgressions are recorded in the region between 4848–4536 and 4335–3949 cal BP. Radiometric dating results from archaeological excavations at Dosariyah, one of the most important Neolithic coastal sites in the Gulf, suggest that occupation of the site during the Neolithic coincides with the mid-Holocene marine transgression (ca. 7200–6500 cal. BP). Whilst the close proximity of the site to the sea may have facilitated maritime exchange activities, occupation of the site was short-lived and the phase of abandonment occurred during a period of rapid RSL rise, which would have transformed the area around Dosariyah into an island or certainly cut it off tidally from the mainland.

Multiproxy analysis of a Lateglacial-Holocene sedimentary section in the Fuegian steppe (northern Tierra del Fuego, Argentina): Implications for coastal landscape evolution in relation to climatic variability and sea-level fluctuations

We report the sedimentology, palynology, geochemistry, and diatom assemblages of a well-dated succession at Laguna Las Vueltas (LV) on the Atlantic coast of the Fuegian steppe in southern Argentina. The multiproxy analysis offers a unique opportunity to study the evolution of this coastal landscape in relation to past sea level and climate changes in the southern high latitudes. After ca. 19,000 cal yr BP, the sediments were subjected to subaerial exposure and oxidation linked to a low sea level. The Sr/Ba ratio (a paleosalinity geochemical parameter) indicates variations in the water body level, and diatoms imply the existence of an ephemeral and brackish-freshwater body subject to desiccation under arid conditions. Between ca. 11,600 and 8500 cal yr BP, a shrubby steppe vegetation, mainly composed of Asteraceae subf. Asteroideae, spread over the coastal area associated with a shallow freshwater body and the deposition of fine-grained sediments in low-energy environments, all indicative of low effective moisture and warm climate conditions. Between ca. 8500 and 8100 cal yr BP, salt carpet vegetation, dominated by Chenopodiaceae, developed around a coastal lagoon in response to the Holocene marine transgression. The record of dinocysts and geochemical data indicate marine influence at this time. Between ca. 8100 and 7000 cal yr BP, salt marshes colonized the coastal area. A coastal lagoon with a more restricted connection to the sea and minor freshwater input are inferred, linked to the beginning of a regressive phase. After ca. 7000 cal yr BP, grassland vegetation and an open shrub stratum developed along with a shallow lake (pan) that was disconnected from the sea, following a fall in the sea level and regression. Fluctuations in the water level of the pan and changes in the physical-chemical conditions, as indicated by fluctuations in Mn/Fe, Ti/Ca, Rb/Sr, Ca, TIC and TOC, suggest abrupt events of desiccation and flooding. Between ca. 4500 and 2000 cal yr BP a drier phase is indicated by changes in vegetation, algal content and geochemistry of the pan. A grassland vegetation and a shallow lake with seasonal water level variations characterized the last 2000 years. Our results from LLV area match well with Andean forest fluctuations and regional climatic conditions recorded from Tierra del Fuego and Chilean southwest.

Pedogenic carbonate crusts (calcretes) in karstic landscapes as archives for paleoenvironmental reconstructions – A case study from Yucatan Peninsula, Mexico

In the northeastern margin of the Yucatan Peninsula, which is located in southeastern Mexico, three levels of compact carbonate crusts (calcretes) interlayered with indurated coastal calcareous sediments (calcarenites) are discernible. Since both the calcretes and calcarenites form a continuous carbonate sequence, a combined methodology (macro- and micromorphology, geochemistry and mineralogy) is used to differentiate them. Additionally, the calcrete layers are dated using the Uranium-Thorium method in order to establish a chronological framework. The carbonate differentiation and chronology are then used to establish the paleoenvironmental conditions that prevailed during calcrete formation as well as to reconstruct the coastal landscape evolution and its relation to Pleistocene sea-level changes during Marine Isotope Stages (MIS) 6 and 5. Samples of calcrete layers and calcarenites were taken from two sections in the Cancun-Tulum corridor. The lowest level of calcrete underlies a sequence of calcarenites, and the two younger levels cap the sequence. In calcretes, the micromorphology provides evidence of the presence of a relict soil with subangular blocky microstructure, root traces, and needle-fiber calcite (associated with soil-fungi interactions). In contrast, the micromorphology of the calcarenites shows ooids and bioclasts, typical of a coastal environment. Geochemically, calcretes are depleted in δ13C, compared to calcarenite, with values ranging between −2‰ and −10‰, and they have a lower proportion of rare earth elements. Calcrete mineralogy consists mainly of calcite over aragonite with a low proportion of Mg-calcite. U/Th dating indicates that the oldest calcrete was formed during the Penultimate Glacial Maximum (PGM), in MIS 6, and the two younger calcretes correspond to the Last Interglacial Period, in MIS 5c. The calcarenite formation occurred earlier, also during MIS 5. Soil formation, strong karstification and soil erosion have occurred on younger calcretes. This study suggests that these processes developed between MIS 4 to MIS 1.

Lower to middle pleistocene coastal dune fields formation in the western mediterranean (Western Eivissa, Balearic archipelago): Chronology and landscape evolution

Abstract Colluvial and aeolian successions in coastal environments are useful indicators of geomorphological changes that occurred during the Quaternary. Pleistocene aeolian deposits interbedded with colluvial deposits and palaeosols in areas of Cap Negret, Punta de sa Pedrera, Cala Bassa and Cala Compte, western coast of the island of Eivissa (western Mediterranean) are studied here. These deposits span almost continuously along 14 km of the coast, covering an area of approximately 22 km2. We present a sedimentological and stratigraphical description of these Pleistocene outcrops. Five major sedimentary facies involving the succession of aeolian, colluvial and edaphic environments are described. Carbonate sandstones, breccias, conglomerates and fine-grained deposits are the main components of these sequences. Optically stimulated luminescence (OSL) dating of aeolian levels indicates that deposition took place from the Lower to Middle Pleistocene. The sedimentological and chronological analysis of these deposits allows reconstructing of the coastal Pleistocene environmental history from Marine Isotopic Stage (MIS) 22 to MIS 6. Results show that the main controls on Lower to Middle Pleistocene coastal landscape evolution on Western Eivissa are changes in the average wind direction over time, modulated by the interaction with coastal relief orientation. The main episodes of aeolian activity identified and dune formation in the Western Mediterranean can be linked to periods of low sea level.

Coastal landscape evolution in the Wilpattu National Park (NW Sri Lanka) linked to changes in sediment supply and rainfall across the Pleistocene–Holocene transition

Coastal sand dunes are sediment archives which can be used to reconstruct periods of aridity and humidity, past wind strength and variations in the sediment supply related to sea‐level changes. In this manner, the sedimentary record of fossil coastal dunes in Sri Lanka provides evidence for environmental and climatic changes during the late Pleistocene and Holocene. As yet, these environmental shifts are poorly resolved because the sedimentary facies and their depositional architecture have not been studied and only very few age constraints are available. Facies analysis of a lithological section at the Point Kurdimalai sea cliff in the Wilpattu National Park (NW Sri Lanka) reveals a striking resemblance to the stratigraphic succession associated with the Teri Sands in southeastern India, which is better dated. The reason is that deposition occurred under the same geological, climatic and geomorphological conditions in the two regions. This special situation allows for litho‐ and climate stratigraphic correlations across the Gulf of Mannar and links the landscape evolution at Point Kudrimalai to late Quaternary climatic events and sea‐level changes. Our results show that the formation of red coastal dunes (Red Beds) in Sri Lanka was a multi‐phase process across the Pleistocene–Holocene boundary and hence the differentiation between an Older Group of Plio‐Pleistocene age (including the Red Beds) and a Younger Group of Holocene age in the Quaternary stratigraphic chart for Sri Lanka is not justified.

Upstream and Downstream Boundary Conditions Control the Physical and Biological Development of River Deltas

AbstractRelative sea level rise is depleting coastal land. Success in coastal restoration depends on understanding interactions between physical and biological processes that influence landscape change. We present results from flume experiments examining the coevolution of vegetation and delta channel networks. We show that channel mobility—controlled by upstream and downstream boundary conditions and delta size—controls vegetation colonization. The spatial patterns of plants in turn control the stability and spatial distribution of channels. Experiments with low‐channel mobility develop large, dense plant patches that become denser over time and stabilize channels. Experiments with more mobile channels have sparse vegetation patterns that limit vegetation growth within existing patches, maintaining sparse, patchy vegetation. Thus, the ecogeomorphic development of deltas depends on the rate of channel lateral migration and avulsion, suggesting that upstream and downstream boundary conditions control both the physical and biological evolution of coastal landscapes.

Coastal landscape evolution of Corsica island (W. Mediterranean): palaeoenvironments, vegetation history and human impacts since the early Neolithic period

A multi-proxy investigation of sediment cores has enabled us to reconstruct the coastal environmental evolution of East-Central Corsica (the sites of Saint Florent, Piantarella-Bonifacio and Palo-Solenzara) for the last 8000 years. The analytical methods comprise pollen (five original pollen diagrams), weight loss-on-ignition measurements, laser granulometry, and ostracod identification. In addition, 26 radiocarbon dates are used to provide a robust chronostratigraphy for the sedimentary sequences. The assessment of coastal landscape dynamics enables us to define the major morphological changes and to evaluate the complex interplay between climatic forcing and anthropogenic activity on the vegetation history of Corsica, within an archaeological context, since the early Neolithic period (∼7.4 cal kyr BP). The major findings are that the first farmers reached Corsica by sea, and they encountered a coastal environment mainly composed of freshwater ponds located close to the shoreline. This specific paleoenvironmental feature offered a favourable location for agriculture and for the development of permanent settlements where a subsistence economy was developed. Since the Middle Holocene, postglacial sea-level rise has caused major changes in local coastal environments, often characterized by salt intrusion into freshwater bodies. At the transition between the Mid and Late Holocene (∼4.0 cal kyr BP), an increase in both salinity and aridity caused substantial landscape changes, mainly characterized by a further expansion of saline marshland, mainly occupied by Chenopodiaceae. The results also provide new insights into the role of Erica in the original Holocene vegetation of Corsica. Our data clearly indicate that an Erica arborea - Quercus ilex forest transition occurred before 6.3 cal kyr BP, significantly earlier than previously proposed. Finally, the earliest evidence of cereal cultivation is at ∼7350 cal kyr BP, and in addition we are better able to constrain the role of humans in the landscape dynamics of Corsica since the early Neolithic.

Late-Holocene coastal depositional environments and climate changes in the Gulf of Corinth, Greece

Multidisciplinary studies in coastal systems of the eastern Mediterranean region have proven to be excellent tools in understanding paleoenvironmental, paleoecological, and paleoclimatic changes that took place during the Holocene period, and how these changes interacted with urban development and growth. This paper presents sedimentological, high-resolution x-ray fluorescence (XRF scanning), micropaleontological, and x-ray diffraction (XRD) data from three shallow sediment cores that were retrieved from Aliki (ancient Siphai or Tipha) salt pond. The study area is located in a unique, highly tectonic geographical region, at the northeast part of the Gulf of Corinth in Greece. Beachrock deposits that form a barrier between the salt pond and the marine environment seem to play an important role in the evolution of the area. The chronological framework was set at around 3100 cal. BP by four 14C radiocarbon dates, and the evolutionary model that was established indicates four different changes taking place during this period at the study area. From around 3100 to 1600 cal. BP, a transition from a closed to an open lagoonal environment was identified, interrupted by a fluvial terrestrial deposit at around 2500 cal. BP. A shift toward a closed lagoonal system at around 1600 cal. BP and the establishment of a salt pond environment seem to correlate with tectonic activity. The study provides important information about the evolution of coastal landscape in such a tectonic active region and points the interaction between regional human activity and climatic changes during the late-Holocene period.