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Formation and evolution processes of natural tombolos involve many interrelated geomorphological, sedimentary, oceanographic and anthropogenic factors, making their measurement and simulation an extremely difficult task. The present study attempts to fill this knowledge gap by detecting the natural tombolos in Greece, formed in the current sea level, through the statistical analysis of their morphometric and socio-environmental parameters. In addition, the long-term evolution of these coastal depositional landscapes has been determined by comparing old aerial photos taken in 1945 or 1960 and recent satellite images taken from 2020 to 2022. Two thirds of the twenty tombolos studied are subject to erosion, while eight are sporadically destroyed and turned into salients. The Greek tombolos are mildly or heavily exploited for touristic purposes, and fourteen of them are protected by national and international environmental laws. Future studies need to focus on the unstable type of these coastal landforms that are modified from tombolo to salient and vice versa to obtain helpful information about the morphodynamic conditions necessary for their evolution. [ABSTRACT FROM AUTHOR]

This paper presents an integrated approach to assess Holocene environmental changes in the Sperchios delta, Sperchios rift, central Greece. A multidisciplinary study was carried out applying established analytical methods as well as exploring new techniques to detect past environmental conditions in a fluvio-deltaic depositional system. A series of six deep boreholes, up to 50 m long, and four shallow cores, up to 6 m long, from across the delta plain, were studied in detail. Sedimentary facies were defined by changes in grain size and macro- and microfaunal composition. Variability in mineral magnetic composition documented by changes in bulk magnetic susceptibility (χ and χ77K/χ293K) and remanence parameters (S−300 and σARM/σSIRM ratios), as well as down-core elemental variations obtained by scanning micro-x-ray fluorescence (µ-XRF), provide constraints on the depositional changes related to the evolution of the Sperchios delta. Correlations between elemental data derived by µ-XRF analyses and grain size were also analyzed and used to further constrain the facies interpretation. Overall, these Holocene sediments reveal a transgressive–regressive succession overlying pre-transgressive terrestrial deposits of Late Pleistocene–Early Holocene age. Furthermore, 13 new 14C radiocarbon dates constrain the transgression rate to be ~3.5 m/yr for the Early Holocene and the regression rate to be ~1 m/yr for the Late Holocene. The Sperchios delta plain developed when the rate of sea-level rise decreased ~6000 cal. yr BP as it has been proposed for the broader area of Aegean Sea. This study demonstrates that the combination of techniques used here provides a powerful way to map out paleoenvironmental changes and thus the 3D stratigraphic architecture of Holocene sedimentary successions. [ABSTRACT FROM AUTHOR]

In some islands of the Aegean, there is evidence of the occurrence of repeated rapid subsidences during the Late Holocene. In this paper, the shape of tidal notches that may be well-preserved underwater is recalled in order to reconstruct sequences of coseismic subsidences and other relative sea-level changes, which occurred during, at least, the last few millennia. A reanalysis of the published measurements of submerged tidal notches in several islands reveals that subsidence trends in many areas of the Aegean are not continuous with gradual movement but, also, are the result of repeated coseismic vertical subsidences of some decimetres at each time. The estimated average return times are of the order of approximately some centuries to one millennium. Although the results cannot be used for short-term predictions of earthquakes, they may provide useful indications on the long-term tectonic trends that are active in the Aegean region. [ABSTRACT FROM AUTHOR]

The reconstruction of millennial-scale interactions between ecosystems and societies can provide unique and valuable references for understanding the creation of cultural landscapes and help elucidate their value, weaknesses and legacies. Among the most emblematic forms of Mediterranean land use, olive groves and pastoralism have occupied a prominent place. Therefore, it is vital to know when, how, and with what ecological consequences these practices were established and developed. Located in the southern part of the Aegean Sea, Crete is the largest island of Greece. The island is characterised by a long human history of land use, but our understanding of past environmental changes for the entire Holocene is fragmentary. This paper presents a new investigation of Lake Kournas in Crete, where recent coring provided a 15-m sequence covering ten millennia of land cover and land-use history. The study of this new core involves the analysis of the sediment dynamics, flood deposits, pollen, diatoms, fungal and algal remains, and microcharcoals. Results show that ecosystem development near Lake Kournas was not a linear process. They reveal linkages and feedbacks between vegetation, biodiversity, fire, human impact, erosion, and climate change. A possible human occupation and agro-pastoral activities around the lake may have been detected as early as 9500 cal BP, perhaps in a transitional phase between the Mesolithic and the Neolithic. At 8500 cal BP, climatic conditions may have promoted the expansion of the evergreen oak woodland. However, human impact was probably the most important driver of ecosystem change with the establishment of an agro-system after 8000 years ago. Thereafter, the trajectory of Kournas' lake and catchment ecosystems from the Mid to Late Holocene follow the rhythm of land-use change. Among the traditional Mediterranean land uses, olive cultivation locally played a major role in the socio-ecosystem interactions, providing economic benefits but also destabilising soils. During the last six millennia, three main phases of olive cultivation occurred during the Final Neolithic-Minoan period, the Hellenistic-Roman-Byzantine (HRB) period and Modern times. Along with the changing land use under the successive political and economic influences rules, the resilience capacities of vegetation permitted it to shift back to higher biodiversity again after decreasing phases. Forest vegetation was always able to recover until the onset of the Venetian period (13th century), when woodlands were dramatically reduced. Only during the past century has forest vegetation slightly recovered, while the flood regime had already been altered during previous centuries. During the past 100 years, biodiversity markedly declined, probably in response to the industrialization of agriculture. • The Lake Kournas core study includes sediment, pollen, NPP, diatom and microcharcoal analyses. • The results reveal almost ten millennia of interactions between climate, human activities, erosion, vegetation and fire. • Climate may have been involved in the first shift around 8500 cal BP that promoted expansion of evergreen oak woodland. • From the Mid to the Late Holocene, the ecosystem trajectory near the lake rather follows the rhythm of land use changes. • Among the traditional Mediterranean land uses, olive cultivation locally played a major role. [ABSTRACT FROM AUTHOR]

Abstract: This paper deals with Holocene coastal changes of the Astakos plain in Akarnania, NW Greece. Palaeoenvironmental scenarios are based on the analysis of the lateral and vertical distribution patterns of sedimentary facies. Sediments from vibracorings were studied using geomorphological, sedimentological, microfaunal, palaeobotanical and geochemical methods. A geochronostratigraphy was achieved by 14C-AMS-dating of organic matter. We present palaeogeographical maps for different points in time since the mid-Holocene. The evolution of the coastal area was generally controlled by the migration of a complex system of a shallow marine embayment, an adjacent lagoonal environment and an adjoining coastal lake forced by the interaction of sea level rise, tectonic movements, and sediment supply from the hinterland. The maximum transgression of the Ionian Sea took place at circa 5500cal BC reaching approx. 1.1km inland. The lagoon as well as the coastal lake had their largest dimensions around 4500cal BC indicating a more humid climatic period. In the course of a long-lasting regression, an asymmetric sedimentation pattern developed. Around 2500cal BC it was characterized by strong fluvial deposition of the Xeropotamos in the western plain and a small and narrow marine embayment with associated lagoonal to limnic coastal water bodies in the eastern plain. The latter were related to karstic springs draining the adjacent Rigani ridge. Around 500cal BC the coastline lay about 200m landward of its present position. Possible harbour sites for the ancient polis of Astakos are (a) the area of modern Astakos where a mole in a position seawards of the present coast would have guaranteed deep water conditions for anchoring, or (b) the southeastern fringe of the plain where deep water prevailed and the nearby freshwater outlet protected the site from rapid siltation. We found increased torrential activity (i) for the 6th–5th millennium BC, (ii) for the 2nd half of the 1st millennium BC until Roman times, and (iii) at the end of the 19th century AD. At least the two younger phases are mostly due to anthropogenic soil erosion. Between the 4th and the 2nd millennium BC a period of ecological stability existed. Relative changes in sea level for the Bay of Astakos were reconstructed for the first time. Since the mid-Holocene, the relative sea level has never reached a higher position than today. It rose from 12.50m b.s.l. at 6200cal BC via 2.20m b.s.l. at 500cal BC to its present level. Besides eustatic reasons, tectonic subsidence due to the half graben structure of the area is the main trigger of the relative rise in sea level. [Copyright &y& Elsevier]

The Greek region is known as one of the most seismically and tectonically active areas and it has been struck by some devastating tsunamis, with the most prominent one being the 365 AD event. During the past decade significant research efforts have been made in search of geological and geomorphological evidence of palaeotsunamis along the Greek coasts, primarily through the examination of sediment corings (72% of studies) and secondarily through boulders (i.e., 18%). The published data show that some deposits have been correlated with well-known events such as 365 AD, 1303 AD, the Minoan Santorini Eruption and the 1956 Amorgos earthquake and tsunami, while coastal studies from western Greece have also reported up to five tsunami events, dating as far back as the 6th millennium BC. Although the Ionian Islands, Peloponnese and Crete has been significantly studied, in the Aegean region research efforts are still scarce. Recent events such as the 1956 earthquake and tsunami and the 2020 Samos earthquake and tsunami highlight the need for further studies in this region, to better assess the impact of past events and for improving our knowledge of tsunami history. As Greece is amongst the most seismically active regions globally and has suffered from devastating tsunamis in the past, the identification of tsunami prone areas is essential not only for the scientific community but also for public authorities to design appropriate mitigation measures and prevent tsunami losses in the future. [ABSTRACT FROM AUTHOR]

Pollen assemblages recovered from a 5 m sediment core from the Vravron coastal marsh suggest a close correlation between vegetation development and human presence in Attica, and provide the first complete record of middle to late Holocene vegetation history. Correlation of pollen with archaeological data attempts to decode the man-environment relations of the past, within the context of the known climatic variability of the mid-late Holocene, in the vicinity of ancient Athens, an area of high historical significance. The pollen record of Vravron denotes a rather variable landscape where open Mediterranean evergreen pine woods alternated with maquis shrublands and grasslands, where human activities and climate have left their imprints on vegetation. During the last 5,000 years agricultural practices displayed several variations: cereal cultivation appears more intense during the Bronze Age, especially in the Mycenaean, while a spread of Olea is observed during Geometric to Classical times. The gradual abandonment of Olea cultivation evidenced in our pollen diagram came as a result of the displacement of human activities in the interior of Mesogaia in Hellenistic and Roman times. Olea and cereal cultivation intensification is observed again during the Mesobyzantine period. In the upper part of the core evidence of intense soil erosion and expansion of Vravron wetland was recorded, coinciding with the Little Ice Age climatic event and the introduction of Arvanites populations in the area. [ABSTRACT FROM AUTHOR]

Recent investigations of the Eastern Mediterranean Sea carried out during the GECO cruise with RV Urania provided a substantial number of new cold-water coral (CWC) records, including branching and solitary scleractinian species. These new sites are located along steep escarpments and on topographic highs along the margins of Crete, Karpathos, and Rhodes. The majority of the corals represent fossil occurrences, predominantly Late Pleistocene assemblages. Our research documents that the Eastern Mediterranean Basin has been colonized by CWC at favorable times during the Last Glacial, in particular during the Younger Dryas. Schizocyathus fissilis is reported for the first time for the Mediterranean, while the finding of Ceratotrochus magnaghii represents the first record for the Eastern Mediterranean. Various coral facies occur on the southerly island slopes of Crete, Karpathos, and Rhodes, including hardgrounds and loose skeletal sediments. Hardgrounds occur on steep topographies between ca. 500 and 1,700 m, and can conveniently be subdivided as (1) Neopycnodonte- Desmophyllum framestone, (2) Desmophyllum- Caryophyllia framestone, (3) Madrepora- Lophelia rudstone, (4) Pelagic mudstone and wackestone, and (5) Siliciclastic-carbonate conglomerate and breccia. Unconsolidated skeletal sediments containing corals mainly occur on gentler topographic situations between ca. 140 and 600 m and can be subdivided as: (A) Lophelia- Madrepora rubble, (B) Dendrophyllia rubble, (C) Stenocyathus rubble, (D) Caryophyllia calveri rubble, and (E) fine-grained sediment with octocoral axes. Many of these facies types are also present in the western part of the Mediterranean and have fossil representatives from the Pleistocene to the Recent. Radiocarbon dating (AMS-C) reveals Younger Dryas ages between 12.4 and 12.0 ka cal BP for Lophelia pertusa and Madrepora oculata. Desmophyllum dianthus occurs during the Last Glacial Maximum (21.8 ka cal BP) and the Younger Dryas (11.7 ka cal BP), as well as during the Late Holocene and subrecent times (4.4-0.6 ka cal BP). Caryophyllia sarsiae occurs during the Late Glacial (15.5 ka cal BP), while Caryophyllia calveri occurs during the Early Preboreal (10.8 ka cal BP). The ages for the framework-constructing corals L. pertusa and M. oculata are coherent with their temporal predominance during the Younger Dryas in other parts of the Mediterranean. [ABSTRACT FROM AUTHOR]

This study presents pollen-based climate reconstructions of Holocene temperature and precipitation seasonality for two high-resolution pollen sequences from the central (Lake Accesa, central Italy) and eastern Mediterranean (Tenaghi Philippon, Greece) regions. The quantitative climate reconstruction uses multiple methods to provide an improved assessment of the uncertainties involved in palaeoclimate reconstructions. The multimethod approach comprises Partial Least Squares regression, Weighted Average Partial Least Squares regression, the Modern Analogues Technique, and the Non-Metric-Multidimensional Scaling/Generalized Additive Model method. We find two distinct climate intervals during the Holocene. The first is a moist period from 9500 to 7800 cal. BP characterised by wet winters and dry summers, resulting in a strongly seasonal hydrological contrast (stronger than today) that is interrupted by a short-lived event around 8200 cal. BP. This event is characterised by wet winters and summers at Accesa whereas at Tenaghi Philippon the signal is stronger, reversing the established seasonal pattern, with dry winters and wet summers. The second interval represents a later aridification phase, with a reduced seasonal contrast and lower overall precipitation, lasting from 7800 to 5000 cal. BP. Present-day Mediterranean conditions were established between 2500 and 2000 cal. BP. Many studies show the Holocene to have a complex pattern of climatic change across the Mediterranean regions. Our results confirm the traditional understanding of an evolution from wetter (early Holocene) to drier climatic conditions (late Holocene), but highlight the role of changing seasonality during this time. Our data yield new insights into the aspect of seasonality changes, and explain the apparent discrepancies between the previously available climate information based on pollen, lake-levels and isotopes by invoking changes in precipitation seasonality. [ABSTRACT FROM AUTHOR]

Macaronichnus segregatis occurs in an upper foreshore conglomeratic to sandy beachrock dating from Roman times, on the east coast of Rhodes, Greece. In some laminae, M. segregatis is strongly oriented perpendicularly to the Recent and Holocene seashore. In other laminae, this trace fossil displays a winding to spiral course. These forms are introduced as new ichnosubspecies, M. segregatis lineiformis, M. segregatis maeandriformis and M. segregatis spiriformis, respectively. It is suggested that these middle-tier trace fossils were produced under conditions of different porewater flow. During higher energy periods, predominantly in winter, water movement perpendicular to the coastline caused M. segregatis to be oriented rheotactically. During periods of more or less stationary pore-water, predominantly in summer, M. segregatis assumed a spiral form. The winding form represents intermediate conditions. Closely beneath the Macaronichnus horizons a large burrow fill was found, probably referable to Psilonichnus isp. In the same beachrock are undertracks attributed to artiodactyls, associated with tracks and a trackway of human origin. The anatomy of the tracks indicates the direction of travel of the trackmakers, eastward and westward along-shore in all cases but one. The morphology of the tracks has been influenced by the gravitational effect of beach slope. Orientation, morphology and structure of trace fossils provide clear evidence that the sandstone and gravel unit is a beachrock and reveal the precise orientation of the paleoshoreline. [ABSTRACT FROM AUTHOR]

During the Holocene, the western part of the present-day Thessaloniki coastal plain (north-central Greece) was flooded by the rising sea level and formed a bay as a consequence of the last postglacial transgression. The rate of the sea-level rise subsequently decelerated, and this bay began to fill with sediments delivered by the Aliakmon and Axios, as well as by other smaller rivers. The palaeogeographic and palaeoenvironmental reconstruction of the Thessaloniki Plain was the focus of several studies published during the past century. Most of these studies are based on the interpretation of historical sources and support the assumption of a fast filling of the bay between the fifth century BC and the fifth century AD. In this work, we first present the results of the analysis of data collected from six boreholes recently drilled in the western part of the plain, up to the western bank of the Axios River. Our study was mainly based on sedimentological and palaeontological analyses and accelerator mass spectrometry and conventional radiocarbon dating of shells and peat. Second, we evaluate the results of this study, as well as of other geological studies, which permit the description of the large-scale stratigraphic pattern of the plain. Data were evaluated on the basis of a geographic information system, used for the first time in such type of work, and were supplemented and assessed with analysis of Landsat imagery. Based on this evidence, we propose a new, detailed palaeogeographic reconstruction for the evolution of the Thessaloniki Plain during the Late Holocene. This plain corresponded to a wide marine bay during the Neolithic times (6000 BP), and later it was characterised by a fast displacement of the shoreline, mainly during Late Bronze Age, Iron Age, and Classical-Archaic periods (2650-2300 BP). A slowing down of the progradation of the alluvial plain occurred during Roman times (2100-1600 BP), and the plain obtained its present-day topography during the second part of the 20th century. [ABSTRACT FROM AUTHOR]

New pollen data from three contrasting sites in northern Greece allow an analysis of spatial and temporal patterns of vegetation change during the Holocene and Lateglacial in northern Greece. At the principal site, Nisi Fen, six cores from the thickest surficial peat deposits have yielded a detailed, composite, AMS 14C-dated pollen record covering the period from 20000 cal. BP almost to the present-day. Cores Kp-4 and Bor-3 were taken from small mires at high elevations in the Boras mountains, a few kilometres to the north of Nisi, in which peat has been accumulating since the mid-Holocene. Our results show that only Pinus expanded significantly during the Lateglacial Interstadial, although small thermophilous tree populations were present in the region. The Younger Dryas chronozone is at best marked by subtle vegetational change in favour of steppe taxa. Tree cover increased rapidly at the beginning of the Holocene, with deciduous woodland probably expanding above its present-day altitudinal limits. There is evidence for drier and/or warmer summers, and mild winters, between c. 10500 and 7500 cal. BP, although the vegetation was not as markedly sclerophyllous as at many sites elsewhere in Greece. The mid-Holocene saw a reorganization of the woodland, with first Abies and then Fagus becoming important at high altitudes, and an increase in the diversity of deciduous woodland at medium elevations. The suggestion of human impact in the form of a decline in woodland and the appearance of crops in the pollen record can be found at all altitudes in the later Holocene. [ABSTRACT FROM AUTHOR]

The Upper Weichselian and Holocene layers of the 190 m thick peat sequence in the Philippi basin (NE Greece) are studied by means of their mineralogical and geochemical features. The ash contents range between 11.4 and 53.4% and inorganic carbon contents range between 0.5 and 5.7%. X-ray diffraction (XRD) analysis revealed that Mg-calcite, quartz, clay minerals, K-feldspars, plagioclases, and chlorites are the dominant minerals in the peat. Lime, pyrite, siderite, apatite, iron-oxides, weddellite, and basaluminite occur subordinately. During Upper Pleniglacial and Late Glacial times, clastic sedimentation prevailed in the palaeomire. Peat was enriched in Fe, K, Ti, As, Cr, Cu, Ni, Rb, Th, Y, Zn, and Zr. In Early Holocene, authigenic sedimentation of Ca-rich material dominated. Peat became enriched in As, Br, Se, Sr, and U. In Middle Holocene, fluctuations of the water table in the mire resulted in the deposition of both authigenic and clastic minerals. The Late Holocene peat is intensely damaged due to drainage and cultivation. The mineral matter features of the Upper Weichselian peat are identical to the features of many Greek lignites. [ABSTRACT FROM AUTHOR]