Coastal Terraces Research Articles

Abiotic and Biotic Processes Controlling Deposition of Calcite and Hydrotalcite Calcretes on Niue Island, Southwest Pacific

Calcretes are indurated terrestrial carbonates that are widespread in arid and semi-arid settings and serve as important archives of present and past environments. Here, we use geochemical tools to explore the nature and origin of calcretes documented from tropical Niue Island in the Southwest Pacific. The study recognizes two types of calcretes that differ in their mineral assemblage, microfabrics, elemental chemistry, and carbon and oxygen isotopes. The calcretes common in the paleo-lagoon soils consist of 90% low-Mg calcite and ~10% highly weathered Mg-Al silicates. These pedogenic calcretes formed in the soil profiles within the vadose zone bear the following distinctions: (i) Fe/Al ratio of 0.75, identical to the ratio in soils (Fe/Al = 0.76 ± 0.5), substantiating the link between the calcretes and soils; (ii) presence of rhizoliths, root voids, micritic nodules, and clasts, which are consistent with a pedogenic calcrete fabric; and (iii) 13C and 18O depletions of −10.6‰ and −5.3‰, respectively, which are compatible with carbon sources from microbial and root respiration, as well as formation in oxygen isotope equilibrium with vadose waters. Unlike the pedogenic calcrete, a rare calcrete from the coastal terrace contains an exceptionally rare hydrotalcite [Mg6Al2(CO3)(OH)16(H2O)4] mineral (65%) coated by microbial films. We contend that the hydrotalcite-rich calcrete was deposited through interaction of dolomite with seawater, similar to the method of producing hydrotalcite in the laboratory. 13C and 18O enrichments of 0.8 to 1.7‰ and −1.0 to −1.6‰, respectively, are in agreement with (i) mixed carbon sources consisting of microbial CO2 degassing, seawater HCO3, and dolomite dissolution, and (ii) oxygen isotope equilibration with seawater-derived fluid.

New Petroglyphs of the Baga-Oygur River (Right Bank) in Northwestern Mongolia

Purpose. The prehistory of the Mongolian Altai is represented by chronologically various archaeological sites, especially the rock art ones. In 2023 (as part of 2019 season), the Russian-Mongolian expedition continued to study the rock art complexes in northwestern Mongolia.Results. On the right bank of Baga-Oygur River, 7 new petroglyphs locations were discovered; the photo and graphic documenting of multi-temporal compositions was performed. In particular, the earliest petroglyphs of the “Kalguty” style were studied. Conclusion. Dozens of images refer to the Bronze Age; images and scenes of the Early Iron and Medieval periods are also discovered. Along with the points where petroglyphs are concentrated and strictly localized, a wide distribution of petroglyphs was noted on boulders lying on coastal terraces, as well as on rocky outcrops and on the peaks of the mountain frame of the river.

Defining management zones for a papaya culture considering soil chemical attributes by fuzzy c-means

In precision agriculture, one of the major problems is the need for a dense sampling grid. A solution to this problem has been the generation of management zones and the correlation between them. This work aims at defining management zones for a papaya culture using the fuzzy C-means grouping method, based on the following soil attributes: phosphorus, calcium, magnesium and potassium; and base saturation. The work was conducted in an approximately 1.2 ha area planted with a commercial culture of Carica papaya L. cultivated in typical Argisol found on the coastal terraces, in the municipality of São Mateus, ES, Brazil. The management zones were defined by the proposed method, based on the following analyses: soil chemical parameters P, Ca, Mg, and base saturation (V), analyzed together; soil chemical parameters P, Ca, Mg, and V, analyzed separately; and, the following combinations of soil chemical attributes Ca-Mg, Ca-V, Ca-Mg-V, P-Ca, P-Mg, P-V, P-Ca-Mg, P-Ca-V, Mg-V, and P-Ca-Mg-V. The generated management zones facilitated an understanding of the spatial variability of the attributes in the study area and the observed similarities between management zones generated from different attributes. In addition, the data were influenced especially by the P and V% attributes. Keywords: Carica papaya L, geostatistics, grouping analysis, precision agriculture.

Fish fauna and environmental factors in river estuaries of small and medium-sized rivers on islands significantly influenced by warm currents.

River estuaries are influenced by terrestrial and marine areas, and have a unique environment that is constantly fluctuating. They are also important habitats for biodiversity conservation. Tanegashima Island is significantly influenced by the Kuroshio Current. Although nearby Yakushima Island has been recognized as a World Natural Heritage site and information on many species has been collected, there is little information on species inhabiting the river estuaries of Tanegashima Island. In this study, the river estuarine ichthyofauna of 26 small and medium-sized rivers on Tanegashima Island was surveyed and a total of 2758 individuals of 29 species and one genus belonging to 15 families were collected. The fish fauna of the river estuaries of Tanegashima Island were classified into three groups, namely the river estuaries where coastal terraces are underdeveloped and drowned valleys are formed, the river group where the riverbed gradient at the mouth is high, and other river groups. Environmental factors selected as being important for ordination of fish fauna were the altitude of the headstreams at the watershed scale, the gradient of the river estuarine area, and the presence or absence of rapids in the estuary. The importance of the geohistorical factor of drowned valley formation, in addition to habitat and watershed scale environmental factors, as a factor on river estuarine fish fauna is an important finding for future conservation of local biota diversity.

Unravelling the morphogenesis of coastal terraces at Cape Laundi (Sumba Island, Indonesia): Insights from numerical models

AbstractThe morphology of coastal sequences provides fundamental observations to unravel past sea level (SL) variations. For that purpose, converting morphometric observations into a SL datum requires understanding their morphogenesis. The long‐lasting sequence of coral reef terraces (CRTs) at Cape Laundi (Sumba Island, Indonesia) could serve as a benchmark. Yet, it epitomizes a pitfall that challenges the ultimate goal: the overall chronology of its development remains poorly constrained. The polycyclic nature of the terraces, involving marine erosion and reoccupation of old coral colonies by more recent ones hinders any clear assignment of Marine Isotope Stages (MIS) to specific terraces, in particular the reference datum corresponding to the last Interglacial maximum (i.e., MIS 5e). Thus, to overcome these obstacles, we numerically model the genesis of the sequence, testing a range of eustatic SL (ESL) reconstructions and uplift rates, as well as exploring the parameter space to address reef growth, erosion and sedimentation. A total of 625 model runs allowed us to improve the morpho‐chronological constraints of the coastal sequence and, more particularly, to explain the morphogenesis of the several CRTs associated with MIS 5e. Our results suggest that the lowermost main terrace was first constructed during the marine transgression of MIS 5e and was later reshaped during the marine regression of MIS 5e, as well as during the MIS 5c and MIS 5a highstands. Finally, we discuss the general morphology of the sequence and the implications it may have on SL reconstructions. At Cape Laundi, as elsewhere, we emphasize the necessity of addressing the development of CRT sequences with a dynamic approach, that is, considering that a CRT is a landform built continuously throughout the history of SL oscillations, and not simply during a singular SL maximum.

Architecture of Shelly beach ridges in a sheltered beach environment in Punta Perdices beach, San Antonio bay, Argentina

On the northern coast of the San Matías Gulf, Argentina, San Antonio Bay is developed, with an approximate area of 160 km2. The region has a diversity of depositional systems, both inside and outside the bay, which are morphologically characterized by the deposits of plains and tidal channels, beach ridges, beaches and dunes. In this environment relatively protected by the Villarino Peninsula, against the high energy of waves coming from the gulf, the circulation of water is governed by a regime of semidiurnal macro-tides with syzygy amplitudes of up to 9 m, which enter through the single channel, communicating the bay to the ocean. The edges of the Villarino Peninsula have a large number of beach ridges, in the form of extensive modern bioclastic deposits, where bivalves with whole, fragmented, and gastropod valves predominate. The objective of this work is the development of models of depositional architecture of the coquinas of the Villarino Peninsula, through terrain mapping (DGPS) and acquisition of lines by ground penetration radar (GPR), in addition to understanding the Holocene-modern sedimentary dynamics of this region. Surveys with GPR were carried out in the sector of Punta Perdices Beach in the Peninsula Villarino sectors of bioclastic deposits, in a total of 23 GP R lines, where there are several sets of beach ridges (Holocene) with an average width of 100 m, which extend for more than 1 km, located in the sheltered area of the bay. The processed and interpreted GPR data were used to investigate the lateral and vertical relationships of the facies, the depositional geometries and geophysical signatures, developed by progradation mechanisms induced by the hydrodynamics of waves and tides. The genesis of these a lot of bioclasts deposits are discussed, mainly due to the macro tide regime of the region and the littoral drift of the semicircular bay, where the geomorphological features of an actual coastal terrace were described. Depositional models of coquinas in Pleistocene, Holocene, and actual beach environments are scarce in the literature. The obtained results can be analyzed and compared to analogues of hydrocarbon deposits.

Oblique Collision of the Bahamas Platform at the Northern Boundary of the Caribbean Plate Recorded by the Late Cenozoic Coastal Terraces of SE Cuba

AbstractThe southeastern tip of Cuba Island is limited to the south by the N‐Caribbean boundary. By revisiting the impressive sequences of coastal terraces of this region, we decipher the Quaternary deformation pattern of this plate boundary. We present a detailed mapping of coastal terraces uplifted over a hundred kilometers of coastline, and U/Th dating. At Punta de Maisí, the deformation pattern shows (a) a faster uplift close to the transform boundary and (b) a northward propagation of folding produced by the convergence of the Bahamas platform toward the Caribbean plate. Along the southern coast of Punta de Maisí, the sequence displays 29 coastal terraces up to 520 m in elevation and a upper Pleistocene uplift rate of 0.23 ± 0.07 mm yr−1. We interpret this deformation as resulting from an offshore north‐dipping reverse fault near the coast. This uplift rate corresponds to 3% to 1.6% of the short‐term horizontal slip rate of Septentrional Oriente Fault Zone (10 ± 0.1 mm yr−1). Along the northern coast of Punta de Maisí, the sequence displays height coastal terraces up to 220 m in elevation and the uplift rates amount to 0.1 ± 0.05 mm yr−1 and likely result from the reverse faulting and folding associated with the offshore North Hispaniola Fault Zone. Uplift rates quickly decrease to the West, in agreement with the westward decrease in the activity of the North Hispaniola Fault Zone due to the docking of the Bahamas Platform against Cuba, while the platform more gently underthrusts Cuba to the East.

Antarctic Ardley Island terrace - An ideal place to study the marine to terrestrial succession of microbial communities.

The study of chronosequences is an effective tool to study the effects of environmental changes or disturbances on microbial community structures, diversity, and the functional properties of ecosystems. Here, we conduct a chronosequence study on the Ardley Island coastal terrace of the Fildes Peninsula, Maritime Antarctica. The results revealed that prokaryotic microorganism communities changed orderly among the six successional stages. Some marine microbial groups could still be found in near-coastal soils of the late stage (lowest stratum). Animal pathogenic bacteria and stress-resistant microorganisms occurred at the greatest level with the longest succession period. The main driving factors for the succession of bacteria, archaea, and fungi along Ardley Island terrace were found through Adonis analysis (PERMANOVA). During analysis, soil elements Mg, Si, and Na were related to the bacterial and archaeal community structure discrepancies, while Al, Ti, K, and Cl were related to the fungal community structure discrepancies. On the other hand, other environmental factors also play an important role in the succession of microbial communities, which could be different among each microorganism. The succession of bacterial communities is greatly affected by pH and water content; archaeal communities are greatly affected by ; fungal communities are affected by nutrients such as . In the analysis of the characteristic microorganisms along terrace, the succession of microorganisms was found to be influenced by complex and comprehensive factors. For instance, environmental instability, relationship with plants and ecological niches, and environmental tolerance. The results found that budding reproduction and/or with filamentous appendages bacteria were enriched in the late stage, which might be connected to its tolerance to rapid changes and barren environments. In addition, the decline in ammonia oxidation capacity of Thaumarchaeota archaeade with succession and the evolution of the fungi-plant relationship throughout classes were revealed. Overall, this research improves the understanding of the effect of the marine-to-terrestrial transition of the Ardley Island terrace on microbial communities. These findings will lay the foundation for more in-depth research regarding microbial adaptations and evolutionary mechanisms throughout the marine-terrestrial transition in the future.

Faster accumulation and greater contribution of glomalin to the soil organic carbon pool than amino sugars do under tropical coastal forest restoration.

Microbial metabolic products play a vital role in maintaining ecosystem multifunctionality, such as soil physical structure and soil organic carbon (SOC) preservation. Afforestation is an effective strategy to restore degraded land. Glomalin-related soil proteins (GRSP) and amino sugars are regarded as stable microbial-derived C, and their distribution within soil aggregates affects soil structure stability and SOC sequestration. However, the information about how afforestation affects the microbial contribution to SOC pools within aggregates is poorly understood. We assessed the accumulation and contribution of GRSP and amino sugars within soil aggregates along a restoration chronosequence (Bare land, Eucalyptus exserta plantation, native species mixed forest, and native forest) in tropical coastal terraces. Amino sugars and GRSP concentrations increased, whereas their contributions to the SOC pool decreased along the restoration chronosequence. Although microaggregates harbored greater microbial abundances, amino sugars and GRSP concentrations were not significantly affected by aggregate sizes. Interestingly, the contributions of amino sugars and GRSP to SOC pools decreased with decreasing aggregate size which might be associated with increased accumulation of plant-derived C. However, the relative change rate of GRSP was consistently greater in all restoration chronosequences than that of amino sugars. The accumulation of GRSP and amino sugars in SOC pools was closely associated with the dynamics of soil fertility and the microbial community. Our findings suggest that GRSP accumulates faster and contributes more to SOC pools during restoration than amino sugars did which was greatly affected by aggregate sizes. Afforestation substantially enhanced soil quality with native forest comprising species sequestering more SOC than the monoculture plantation did. Such information is invaluable for improving our mechanistic understanding of microbial control over SOC preservation during degraded ecosystem restoration. Our findings also show that plantations using arbuscular mycorrhizal plants can be an effective practice to sequester more soil carbon during restoration.

Reconstruction of relative sea-level changes based on a multiproxy study of isolated basins on the Onega Peninsula (the White Sea, northwestern Russia)

This study presents the results of lithological, diatom, geochemical analyses and radiocarbon chronology of the bottom lake sediments and peat bogs in the central part of the Onega Peninsula (the southern coast of the White Sea): Lake Maloye Murakanskoye (11.0 m a.s.l.), Lake Zhirovskoye (9.5 m a.s.l.), Lake Murakanskoye (7 m a.s.l.), and the Gorbovatiy Mokh bog (6.5 m a.s.l.). The bottom topography and sediments of Lake Murakanskoye were examined using sonar and ground penetration radar (GPR) survey, whereas in the other locations only the water depth was measured. Then, the digital models of the lake bottom topography were created. As an additional indicator of the relative sea-level (RSL) position, we used data on the altitude of the coastal terraces. Evidences of two transgressions in the White Sea (late glacial and Middle Holocene) are revealed. The transgressions were interrupted by two regressions (Early and Late Holocene). Our studies do not allow us to make a clear conclusion about the time and maximum level of the late glacial transgression. However, we may suggest that its level was above 11 m a.s.l. The regression of the Early Holocene started before 10.6–10.2 ka cal BP when the water level in the study area dropped below the altitude of 11m. At 9.4–9.1 ka cal BP the RSL was at an altitude of ca 7m. The Middle Holocene transgression (Tapes) started after 8.4 ka cal BP. The maximum level was reached before 7.4 ka cal BP and did not exceed an altitude of 9.5 m. The RSL stabilized at an altitude about 8.5–8 m during 7.4–6.0 ka cal BP. During 6.0–3.9 ka cal BP RSL very slowly decreased or fluctuated by the level of 8–7 m. RSL began to fall from the 7 m altitude about 4.0–3.9 ka cal BP and by 2.7–2.3 ka cal BP the sea-level reached 4.5 m. After that RSL dropped to its modern position. During the last 4.0 ka cal BP the rate of RSL fall was approximately 0.17–0.18 cm/year.

Lithology Characteristics and Diagenesis of Late Pleistocene-Holocene Coastal Terraces of the Yemeni Red Sea: Implication for Paleoclimatic Records

The development of Holocene-Pleistocene fringing reefs in the Yemeni Red Sea (YRS) is controlled by sediment input and variations in accommodation space. Lithostratigraphic correlation of environmental facies in the investigated sites shows a sequence of successive events, and each can be subdivided into 2 or 3 main sequences. The upper sequence is characterized by the dominance of coral and coralline algal frameworks. The lower sequences are varied and can be attributed to spatial and temporal variability. Meteoric diagenesis is the most dominant and includes dissolution, calcrete, and coral recrystallization. Lithologic and mineralogic investigations of the Pleistocene-Holocene coral reefs display three aerial to subaerial diagenetic environments. These include freshwater-vadose, meteoric-marine-phreatic, and meteoric-phreatic zones represented at Al-Hajaja-Dhubab (Tr1), Perim (Mayyun) island (Tr2 and Tr3), and Kamaran island (Tr4) terraces. The effects of burial diagenesis increase progressively with depth, initially within the vadose zone and, ultimately, into the underlying phreatic zone. The phenomenon of dolomitization and siderisation processes are also occurring in the sections that exhibit brine and freshwater interaction with the iron-rich basaltic rocks. Climatic variation during interglacial-glacial cycles and the wind systems that prevailed in the area have contributed largely to the final deposition. The transition from interglacial to glacial climates in Arabia was characterized by higher effective rainfall, accompanied by aeolianite dissolution and karstification.

Integrated geophysical and geochemical assessment of submarine groundwater discharge in coastal terrace of Tiruchendur, Southern India

Submarine groundwater discharge (SGD) study is essential for groundwater in coastal terrace at Tiruchendur. The famous Murugan Temple is located in the area and around 25,000 people who visit this temple use the SGD well water at NaaliKinaru (a small open well) as holy water and drink it. The rock and soil type are sandy clay, silt, beach sand, calcarenite, kankar, gneissic rock and charnockite in base rock. Megascopic identification method was used to identify the porous and permeable rocks such as calcarenite, sandstone and kankar to support to increase SGD flux. Grain size study was used to identify the paleo-coastal estuarine environment with sediment deposits in the terrace. The square array electrical resistivity method was used to study the subsurface geology and aquifer depth. The 2d ERT technique was used to identify the subsurface shallow perched aquifer of freshwater. The magnetotelluric survey method was used to scan the entire subsurface geological and tectonic uplift, coastal ridges, rock folded subsurface structural features of continental and oceanic tectonism. Darcy’s law was used to calculate the SGD flux rate in the above study area.

The Cuban staircase sequences of coral reef and marine terraces: A forgotten masterpiece of the Caribbean geodynamical puzzle

The emerged sequences of coral reef and marine terraces of the Cuban Archipelago have been recognized since the end of the 19th century but with noticeable exceptions, their bio-constructions and/or deposits are not dated. The northern Caribbean islands and associated archipelagos are located in a left-lateral strike-slip tectonic setting, at the boundary between the North America and Caribbean plates. Cuba is the only landmass located on the American Plate directly adjacent to this transform fault zone. Quantifying upper Pleistocene coastal uplift is thus key to elucidate the recent vertical deformation of the Caribbean geodynamic puzzle with regards to the active tectonic segmentation of this area. We compiled bibliographic data and present new measurements concerning the Cuban sequences of coral reef and marine terraces; maximum elevations, minimum number of successive strandlines and elevation of the lowermost terrace. The Cuban Archipelago exhibits five main uplifting coastal stretches separated by subsiding areas, with at least 23 emerged staircase sequences of coastal terraces. At four sites, the lowest coral reef terrace has been previously correlated to the Last Interglacial Maximum (MIS 5e, 122 ± 6 ka). At nine sites, we extended the morpho-stratigraphy to derive Upper Pleistocene apparent and eustasy-corrected uplift rates. Alongshore Cuba, MIS 5e coastal terraces and associated shoreline angles occur at elevations ranging from 7 m to 40 m, yielding eustasy-corrected uplift rates ranging from 0.06 ± 0.01 mm.yr−1 (NW Cuba) to 0.33 ± 0.01 mm.yr−1 (SE Cuba). More than 400 km northward of the transform fault, eustasy-corrected uplift rates (0.13 mm.yr−1) suggest that the whole Cuban Archipelago is affected by the North America/Caribbean plate motion, with a partitioned compressive component resulting in block tectonics with tilting controlled by regional faults.

Faster recovery of soil biodiversity in native species mixture than in Eucalyptus monoculture after 60years afforestation in tropical degraded coastal terraces.

Afforestation is an effective method to restore degraded land. Afforestation methods vary in their effects on ecosystem multifunctionality, but their effects on soil biodiversity have been largely overlooked. Here, we mapped the biodiversity and functioning of multiple soil organism groups resulting from diverse afforestation methods in tropical coastal terraces. Sixty years after afforestation from bare land (BL), plant species richness and the abundance of plant litter (398±85gm-2 ) and plant biomass (179±3.7tha-1 ) in native tree species mixtures (MF) were restored to the level of native forests (NF; 287±21gm-2 and 243.0±33tha-1 , respectively), while Eucalyptus monoculture (EP) only successfully restored the litter mass (388±43gm-2 ) to the level of NF. Soil fertility in EP and MF was increased but remained lower than in NF. For example, soil nitrogen and phosphorus concentrations in MF (1.2±0.2gkg-1 and 408±49mgkg-1 , respectively; p<0.05) were lower than in NF (1.8±0.2gkg-1 and 523±24mgkg-1 , respectively; p<0.05). Soil biodiversity, abundance (except for nematodes), and community composition in MF were similar or greater than those in NF. In contrast, restoration with EP only enhanced the diversity of microbes and mites to the level of NF, but not for other soil biota. Together, afforestation with native species mixtures can end up restoring vegetation and most aspects of the taxonomic and functional biodiversity in soil whereas monoculture using fast-growing non-native species cannot. Native species mixtures show a greater potential to reach completely similar levels of soil biodiversity in local natural forests if they are received some more decades of afforestation. Multifunctionality of soil biotic community should be considered to accelerate such processes in future restoration practices.

Reconstructing the Holocene environments in the Russian sector of the Neman Delta area, Kaliningrad Region

A history of landscape development in the Russian part of the Neman Delta area during the Holocene, with an emphasis on the formation of forests and wetlands, is deduced based on pollen analysis, radiocarbon dating, a field topography survey, and macrofossil analysis of peat deposits in a coastal mire, the Koz’ye Bog. Several 1,000–2,000-year time lags in vegetational development were revealed here, though they have not been recorded for other landscapes in the Kaliningrad Region and the adjacent areas in the southeastern Baltic. The causes are still not completely clear, but they presumably related to some of the regional patterns of climate development and the submergence of the area during the second Littorina transgression (7,500–7,000 cal. yr BP). It is established that cryophilic open tundra-like vegetation existed here not only in Late Glacial time (Younger Dryas) but up to the mid-Boreal (9,700–9,500 cal. yr BP). A transition from the open landscapes of the Late Glacial to birch and then pine forests occurred here 9,700–8,700 cal. yr BP, whereas the expansion of thermophilic broadleaf species of the nemoral (temperate) association ( Quercus , Ulmus , Tilia , Corylus ) was recorded only in the period 6,400–3,500 cal. yr BP. Peak expansion of Alnus occurred here only in the late Subboreal (3,500–2,700 cal. yr BP), while in adjacent areas it reached its maximum as early as the Atlantic. The general vegetation dynamics in this area during the Late Glacial and the Holocene could be referred to as a transition from the dominance of pine forests to a wide dispersal of alder carrs. This environmental shift was caused not only by climatic factors but probably also due to the transformation of the hilly coastal terrace into a low-lying plain landscape after flooding during the transgressions of the Baltic.

Fossil maerl beds as coastal indicators of late Holocene palaeo-environmental evolution in the Bay of Brest (Western France)

The Bay of Brest (BB) is a mixed, tide-dominated estuarine system. The shore terraces of this bay are occupied by modern free-living (calcareous) coralline algae locally termed “maerl”, organized in bed-like morphologies (rhodolith deposits). Cores retrieved from around the bay reveal fossilized primitive maerl beds of Holocene age, interbedded in sandy-silt sedimentation. The alternation between biogenic constructions and estuarine sedimentation may provide evidence of varying environmental conditions of the late-Holocene period. This paper mainly focuses on the results of chronostratigraphic and bio-sedimentological interpretations of coring data collected in less than 15 m of water depth in an attempt to decipher the main stages of maerl colonization in the bay. In particular, this study raises several significant points allowing to draw links between centennial to millennial-scale climatic changes in marine estuary sedimentation and episodes within the development of maerl biocenoses. The paleo-bathymetry of the coastal terraces has not changed significantly over the last 5000 years. Yet, the first maerl occurrence only appeared around 2000 cal yr B.P., likely showing that the environmental conditions were not favorable for their emergence prior to that time. Pioneer maerl beds developed on coarse shell deposits inherited from the paleostorms affecting the Atlantic coasts during the colder climatic period of the Iron Age (3100–1950 cal yr B.P.). The accumulations then aggraded at various and discontinuous rates, sometimes reaching up to 2.1 m/kyr. Maerl beds temporarily disappeared in the southern part of the Bay of Brest when sedimentation rates increased throughout the bay during the Dark-Age cold period (1375–1250 cal yr B.P.), suggesting that maerl formations could not keep up with sedimentation rate exceeded a certain threshold. Muddy sedimentation conditions also dramatically changed on two occasions, with the establishment of coarse storm levels, set at the intervals 825–600 cal yr B.P. (MWP) and 113–0 cal yr B.P. But maerl deposits reseed the environment as a result of each new cold period, demonstrating the persistence of such coralline algae against drastic palaeoenvironmental changes in coastal areas.

Predictability of Invasive Argentine Ant Distribution Across Mediterranean Ecoregions of Southern California

The invasiveness of nonnative taxa can vary across a landscape due to environmental gradients, suggesting that location-dependent management strategies may be more effective at reducing spread compared to a “one size fits all” approach across the entire introduced range. Using bait stations placed along linear transects within habitat preserves, we tested for effects of ecoregion, vegetation, soil moisture, habitat edge type (i.e., moisture source), and distance from edges on the presence of the invasive Argentine ant Linepithema humile in San Diego County, California, a region with high indigenous biodiversity and numerous rare and protected species. Our results showed an inverse relationship between the presence of native ant species and the presence of the Argentine ant across ecoregions, with the latter reaching peak abundance in the coastal terrace. Argentine ant presence was negatively associated with distance from all edge types regardless of location, but the magnitude of this effect varied among ecoregions. In the xeric foothill and inland valleys, the probability of occurrence was nearly 0 at distances of 200 m and 750 m from moisture edges, respectively, whereas in the coastal terrace, the probability remained above 0.80 at distances up to 1.25 km. When compared to previous studies at different spatial scales, these findings provide an alternative perspective on the invasiveness of the Argentine ant at the landscape level. Our results further suggest that efforts to control spread in regions with a Mediterranean climate may be more successful in inland areas, where the ant is likely to have lower environmental tolerance and native ant species may be better able to generate biotic resistance. In contrast, different tactics and expectations may be necessary for coastal areas, where the same constraints are diminished or absent.

Новые погребения предскифского времени с территории Волгоградской области. Проблемы интерпретации

The article is devoted to the publication and analysis of new burial materials of the pre-Scythian period (9th – 7th centuries BC), obtained as a result of excavations of several burial mounds in the Volgograd region. The work was carried out by the expedition of Volgograd State University from the end of the past to the beginning of the present century. The burial mounds were located on the coastal terraces of the Don river and some of its tributaries, as well as on the steppe watersheds associated with the Don basin. The sample includes seven pre-Scythian burials, the burial rite and clothing material of which allows us to correlate them with the previously discovered monuments of the Chernogorovskaya Culture of the southern Russian steppes and date them within the boundaries of the initial stage of the early Iron Age. According to archaeological and anthropological data, various components were involved in the formation of this culture in the Lower Volga region and the neighbouring Don and the Volga-Ural regions. The basis was autochthonous substrates of the Late Bronze Age, as well as cultural formations derived from them at the final stage of the Late Bronze Age. The combination of local and imported cultural traditions is also reflected in the grave inventory of the studied series, especially in the ceramic complex, which shows technological and typological features of various origin. The variety of elements of the funeral rite and the mixed nature of the accompanying inventory of the presented burial series reflect the complex processes of cultural genesis in the Lower Volga region in the pre-Scythian period during transition to a nomadic economy.

The Oyambre coastal terrace: a detailed sedimentary record of the Last Interglacial Stage in northern Iberia (Cantabrian coast, Spain).

ABSTRACTA detailed study is presented of a 15.3‐m‐thick Pleistocene coastal terrace located on the Cantabrian coast (northern Spain). Stratigraphic, sedimentological, topographic and micropalaeontological information is combined with a chronology based on luminescence dating to characterize the deposits. The sedimentary succession records: (i) a basal transgressive system, consisting of a wave‐cut surface covered by a lower layer of beach gravels and upper beach pebbly sands; and (ii) a thicker upper highstand system (aggrading), comprising medium to very fine aeolian sands interbedded with thin palustrine muds. Luminescence dating involved a detailed sampling strategy (36 samples and two modern analogues) and the use of both quartz optically stimulated luminescence (OSL) and feldspar post‐infrared infrared stimulated luminescence single aliquot regeneration protocols; feldspar results were used to confirm the completeness of bleaching of the quartz OSL signal. The quartz OSL luminescence age–depth relationship shows significant dispersion, but nevertheless two rapid phases of deposition can be clearly identified: one at ~130 ka [Marine Oxygen Isotope Stage (MIS) 5] and one at ~100 ka (MIS 5c). The top of the succession is dated to ~70 ka. The MIS 5e marine maximum flooding surface is identified at an elevation of 6.85 m above mean seal level. This elevation provides evidence of a regional sea‐level highstand for this sector of the Cantabrian coast.

Terrace formation and preservation: Santa Catalina Island and other California Channel Islands

ABSTRACT Uplifted coastal terraces are present on Santa Catalina Island, but so poorly preserved that researchers have debated for more than a century whether they even exist. Morphometric analyses of LIDAR-based topography on the California Channel Islands suggest that the poor expression of terraces on Catalina Island is due a combination of (1) geological conditions less conducive to terrace formation than on the other Channel Islands and (2) high landslide susceptibility around Catalina’s coastal margin that is erasing terrace morphology and deposits before they can reach the island's relatively un-dissected interior. Both of these factors seem to be related to the mechanical properties of the island’s predominant rock type, the Catalina Schist. Several of the other Channel Islands – such as Santa Barbara, San Clemente, Anacapa, and San Miguel Islands – have topography that is dominated by their terrace morphology, mostly by virtue of the small size of those islands. Of the large islands, Santa Rosa has the most extensive terraces, apparently driven by the prevalence of shallowly dipping sedimentary rock. Looking at terrace preservation generally, subhorizontal sedimentary units seem to represent an optimum between promoting the initial creation of wide terrace platforms and resistance to terrace erosion thereafter.