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Detailed geoarchaeological studies were conducted at the Groβkrotzenburg floodplain (Southern Hesse, Germany) in order to reconstruct the fluvial palaeogeography and search for Roman harbour installations. Another objective was to reconstruct the local flood history based on stratigraphic and geochronological data. Prospection based on electrical resistivity tomography, vibracoring and direct push electrical conductivity logging were carried out to detect and analyze subsurface stratigraphies. Altogether, 6 sediment cores, up to 7 m long, were drilled along transects along and perpendicular to the present course of the River Main. Based on sedimentological and geochemical data, we classified four sedimentary units. Vibracore data helped to detect the pre-Holocene bedrock topography and to differentiate between sedimentary facies. We present geophysical, sedimentary and geochronological evidence of a river channel right in front of the Roman fort that was probably active during Roman times. Moreover, we found another bridge pier candidate in the prolongation of a well documented Roman bridge. Our findings further indicate that the northern riverbank has shifted towards south since Roman times. However, neither sedimentary nor archaeological evidence for harbour installations could be brought to light. Nevertheless, we assume that conditions favorable of a river harbour, namely permanent water flow and sufficient water depth, were guaranteed in front of the fort where an undercut slope was probably already existing during Roman times. Several sequences of coarse-grained, sandy to gravelly river deposits were found associated with major flood events that affected the site at Groβkrotzenburg during late Medieval and modern times. At that time, central Germany was repeatedly influenced by extreme meteorological conditions and associated extreme runoff events. Based on radiocarbon data we were able to define two periods of major flooding, namely between 1435 and 1484 cal AD and 1646–1792 cal AD. These periods are contemporaneous with periods of increased flood frequency in Central Europe, derived from historical sources, namely 1430–1460 AD and 1730–1790 AD. Based on sedimentary and geo-chronostratigraphic evidence, major flood events detected at the Groβkrotzenburg alluvial plain are most probably related with the AD 1480, AD 1573 and AD 1780 events known from historical records. Our results document that few historical flood events controlled the overall development of the fluvial landscape at Groβkrotzenburg at least since Roman times until the late 19th century, namely by eroding pre-existing fluvial deposits, accumulating thick sequences of event deposits and narrowing the riverbed. Since the late 19th century, river regulation measures severely changed the hydrological conditions of the River Main.

International audience; After the 2004 Indian Ocean (IOT) and the 2011 Tohoku-oki tsunamis, new research in tsunami-related fields was strongly stimulated worldwide and also in the Mediterranean. This research growth yields substantial advancements in tsunami knowledge.Among these advancements is the “Paleotsunami” research that has marked particular progress on the reconstruction of the tsunami history of a region. As an integration of the historical documentation available in the Mediterranean and the Gulf of Cadiz areas, geological and geoarchaeological records provide the insights to define the occurrence, characteristics, and impact of tsunamis of the past. Here, we present the recent advancements done for both the onshore and offshore realms.As for the onshore, we discuss case studies dealing with recent high-resolution works based on: a) direct push in situ sensing techniques, applied to identification and characterization of typical paleotsunami deposits features; b) combined XRF-X-CT approach, implemented for the identification of fine-scale sedimentary structures useful for the definition of the causative flow dynamics; c) the geoarchaeological “new field” contribution, with the development of specific diagnostic criteria in search for tsunami impact traces in archaeological strata; d) comparison of multiple dating methods and of different modeling codes for the definition of the potential source for the displacement of boulders of exceptional dimension, identified by 3D size calculation.As for the offshore advancements, we present case studies focusing on the recognition of tsunami deposits and their sedimentary traces in the geological record from the nearshore, thanks to diver-operated coring equipment, down to the continental slope, by means of vibracorer and long gravity core sampling in deeper areas. The examples provided show a multiproxy approach with a high potential of retrieving a complete record of paleotsunami traces at least during the Holocene. This is based on the combination of multidisciplinary approaches including X-ray imaging, high-resolution measurement of physical properties, X-ray fluorescence data, grain-size analysis, micropaleontology, palynological content, isotopic and optically stimulated luminescence dating methods.

Frontiers in Earth Science 9, 1-17 (2021). doi:10.3389/feart.2021.599986, Published by Frontiers Media, Lausanne

We present a case study of a bog showing how an integrated approach of multi-method geophysical sounding and local soil sampling can be used to identify, differentiate, and map organic sediments. Our study is based on ground-penetrating radar (GPR), electrical resistivity tomography (ERT) and shear-wave seismic (SH seismic) profiling applied to sediments of the former Lake Duvensee (northern Germany), nowadays a bog. This is a well-known locality for remains from the Mesolithic hunter-gatherers&rsquo, occupation that has been attracting archaeological and geoarchaeological research for100 years. The bog is embedded in low conductive glacial sand and is characterized by layers of different gyttja sediments (detritus and calcareous). The present study was conducted in order to identify the bog morphology and the thickness of the peat body and lake sediments, in order to understand the basin evolution. To validate the geophysical results, derived from surface measurements, drilling, soil analyses as well as borehole guided wave analysis of electromagnetic waves and Direct-Push (DP-EC) have been carried out and used for comparison. It turned out that each method can distinguish between sediments that differ in grain size, particularly between peat, lake sediments (gyttjas and mud) and basal glacial sand deposits. GPR is even able to separate between strongly and weakly decomposed peat layers, which is also clear considering resistivity variations in the ERT computation. From the association between geophysical properties and sediment analysis (e.g., water content and organic matter) different gyttjas were distinguished (coarse and fine) and seismic velocity was correlated to bulk density. Moreover, GPR and SH-wave seismics present different resolutions, confirming that the latter allows measurements, which are more focused on determining the extension of basal sand deposits, the depth of which is difficult to reach with GPR. Representative values of electrical resistivity, dielectric permittivity, and shear wave velocity have been determined for each sediment type and are therefore available to complete the investigation of wetland environments. Fine grained lake sediments were difficult to differentiate by the applied methods. This could be a result of high ionic concentration within the permanent groundwater body, partly masking the sediment properties.

Geophysical and geoarchaeological investigations were carried out in the Wadden Sea of North Frisia (Schleswig-Holstein, Germany) to elucidate major environmental changes that considerably altered the coastal landscape since medieval times. Between the 12 th and 14 th cent. AD, the present-day tidal flats around the marsh island Hallig Sudfall belonged to the historical Edomsharde district and its main settlement Rungholt . For North Frisia, it is well known that during medieval and early modern times, extreme storm surges caused major land losses associated with a massive landward shift of the coastline. Today, cultural traces like remains of dikes, drainage ditches, terps or even plough marks are still visible in the Wadden Sea and provide evidence of the once cultivated marshland. Based on a multi-proxy analysis of sediment cores retrieved from the tidal flat zone around Hallig Sudfall and from the Hallig itself, we identified a late medieval paleosol associated with the formerly cultivated marshland most probably belonging to the Edomsharde and local trade centre of Rungholt. Around Hallig Sudfall, remains of medieval marsh deposits were found partly eroded and covered by a coarse-grained high-energy deposit including abundant shell debris and artefacts. Based on sedimentological, micropaleontological, geochemical and geochronological data, we conclude that these deposits are associated with the 1 st Grote Mandrenke (or St. Marcellus’ flood ), an extreme storm surge event in 1362 AD. Our results, for the first time, provide geological evidence of this 1362 AD storm surge for the Wadden Sea of North Frisia. Moreover, marshland on Hallig Sudfall dating to the 17 th -18 th cent. AD was found covered by a thick layer of storm surge sand and shell debris which seems to be associated with one of the major storm event that hit the German North Sea coast in modern times, e.g. the 2 nd Grote Mandrenke (or Burchardi flood ) in 1634 AD or the Christmas flood in 1717 AD.

In this paper, we present for the first time geomorphological, sedimentary and microfaunal evidence of palaeotsunami impact on Corfu (Ionian Islands, Greece). The island of Corfu is located in an area of exceptional tectonic stress: towards the south, the African oceanic plate is being subducted underneath the Aegean plate, whereas towards the north, the Adriatic and European plates form a continental collision zone. Recent publications provide evidence of earthquake related co-seismic movements that potentially trigger extreme wave events as well as relative sea level fluctuations. In this context, we investigated two selected near-coast geological archives – the Chalikiopoulou Lagoon in the east and the Korission Lagoon in the southwest of Corfu Island. Our results clearly document that the eastern as well as the southwestern coasts of Corfu were repeatedly affected by palaeotsunami impact during the Holocene. With regard to the local topographical constellation and the recent geomorphodynamic potential of each study area, evidence of high-energy wave impact is based on the stratigraphical and microfaunal record of selected vibracoring sites as well as on numerical modelling results. It is concluded that the eastern coast of Corfu is preferably affected by high-energy wave impacts from a southern direction. Such impacts are most likely related to teletsunamis from the major seismical zone of the Hellenic Trench. In contrast, the southwestern coast of Corfu is endangered by impacts from both western and southern directions. Such impacts may comprise teletsunamis triggered in the Hellenic Trench or the Etna regions but may also be caused by local submarine landslides at the steeply sloping continental shelf directly west of Corfu. Our study builds a bridge between palaeotsunami-research conducted in the southern Ionian Sea and the Adriatic Sea and allows to better discriminate between the effects of teletsunamis and locally triggered events within one of the seismically most active regions in the eastern Mediterranean.

In antiquity, the harbour-city of Corcyra (modern: Corfu) was a prevailing naval power in the Mediterranean and had several harbours to host a considerable fleet. Today, these harbours are totally or partly silted and concealed under modern urban infrastructure. Comprehensive geoarchaeological studies were conducted on the northeastern fringe of the Analipsis Peninsula where excavations have revealed the archaeological remains of a massive quay wall (Pierri and Arion sites). These remains are located east of known ancient harbour structures that belong to the Alkinoos Harbour. Our study aimed to reconstruct the palaeoenvironmental setting of the harbour facilities at the Pierri site, including the analysis of the local sedimentary record in order to detect and differentiate natural and man-made triggers that caused environmental shifts. At the Pierri site, we found geoarchaeological evidence for an ancient harbour basin related to the prominent quay wall. Associated harbour sediments indicate a protected harbour which was developed from an open shallow marine environment, most probably by the construction of breakwaters. Harbour deposits were dated using radiocarbon analyses and diagnostic ceramic fragments to the 4 th to 3 rd cent. BC. This is in good agreement with the age of the harbour installations as such archaeologically assigned to the Classical and Hellenistic period. The Pierri site was possibly in function as a harbour facility even before the 4th cent. BC. In any case, it was strongly hit by an earthquake and associated tsunami event during Classical to Hellenistic times. By this event, the harbour was uplifted and covered by event deposits so that it was not usable any more. It was subsequently buried by anthropogenic and colluvial sediments. Overall, the Pierri coastal archive allowed to identify three distinct tsunami landfall events, namely before 2483–2400 cal BC (event I), after 2483–2400 cal BC and before 370–214 cal BC (event II), and during Classical to Hellenistic times, most probably between the 4 th and 3 rd cent. BC (event III). Another tsunami event (event IV) potentially hit the site when it was dry land. Ages of tsunami events I–II and candidate tsunami IV are consistent with tsunamis known from the coasts of western Greece and southern Italy and where thus classified as supra-regional tele-events. Event III was identified as associated to a local earthquake and tsunami by which Corfu Island was uplifted and, at the same time, tilted with a vertical offset of 1.74 m from W to E.

The southwestern coast of Crete, one of the most seismically active regions in Europe, experienced co-seismic crust uplift by 9 m during the Ms = 8.3 mega-earthquake that struck the eastern Mediterranean world on 21 July AD 365. An associated tsunami event caused thousands of fatalities and destroyed many coastal settlements and infrastructure between the Levante in the east and the Adriatic Sea in the northwest. So far, coastal sedimentary archives in southwestern Crete including distinct palaeotsunami fingerprints are rarely investigated. Therefore, a multi-proxy study including sedimentological, geochemical, geochronological, and microfaunal methods was conducted in order to detect onshore coastal sedimentary archives that functioned as fine sediment traps and document palaeotsunami imprint. We found adequate archives at the Sougia and Palaiochora coastal plains that were used to reconstruct the palaeogeographical evolution and the palaeoseismological history of SW Crete during the late Holocene. Our studies revealed distinct geomorphological, sedimentological, geochemical, and microfaunal traces of high-energy impact from the marine side related to seismic events. At the Sougia coastal plain a sheet of fine sand with a neat microfossil and geochemical fingerprint was found sandwiched between underlying pre-tsunami muds and overlying post-tsunami colluvial silt. In the Palaiochora coastal plain, tsunami overflow of a flat Neogene bedrock platform led to the accumulation of sand-dominated deposits that were subsequently covered by colluvial material from the adjacent hillslopes. Based on radiocarbon and luminescence dating approaches, it is shown that the AD 365 tsunami event is the best-fit candidate for the tsunami-related sediments deposited at both, Sougia and Palaiochora. This study, for the first time, presents multi-proxy evidence of the AD 365 tsunami imprint on fine-sedimentary archives along the western and southwestern coast of Crete.

The coastal deposits of Bonaire, Leeward Antilles, are among the most studied archives for extreme-wave events (EWEs) in the Caribbean. Here we present more than 400 electron spin resonance (ESR) and radiocarbon data on coarse-clast deposits from Bonaire’s eastern and western coasts. The chronological data are compared to the occurrence and age of fine-grained extremewave deposits detected in lagoons and floodplains. Both approaches are aimed at the identification of EWEs, the differentiation between extraordinary storms and tsunamis, improving reconstructions of the coastal evolution, and establishing a geochronological framework for the events. Although the combination of different methods and archives contributes to a better understanding of the interplay of coastal and archive-related processes, insufficient separation, superimposition or burying of coarse-clast deposits and restricted dating accuracy limit the use of both fine grained and coarse-clast geoarchives to unravel decadal- to centennial-scale events. At several locations, distinct landforms are attributed to different coastal flooding events interpreted to be of tsunamigenic origin. Coastal landforms on the western coast have significantly been influenced by (sub)-recent hurricanes, indicating that formation of the coarse-clast deposits on the eastern coast is likely to be related to past events of higher energy.

This paper addresses the obvious controversy between the so far published sea level curves of the Black Sea and the Mediterranean. It starts with a discussion of the methods of reconstructing sea level curves, the evaluation of sea level indicators, and the application of the radiocarbon dating method. At least since 7500 BP, when the Black Sea and the Mediterranean were connected, both water bodies must have reacted synchronously on glacio-eustatic changes. It is documented that none of the Mediterranean sea level curves shows the major wiggles postulated for the Black Sea which are supposed to reflect trans- and regression cycles. The very shallow bathymetric condition of the Azov Sea and the northern Black Sea should have led to considerable and traceable shoreline displacements. There is neither archaeological nor historical evidence of mid- and late-Holocene regressions of several meters. The tectonic setting of the Black and Azov seas implicates that the tectonic signal often overrides the eustatic one. Therefore, only local sea level curves can be established. In this paper, based on vibracores, a locally valid sea level curve for the Taman Peninsula is demonstrated. Layers of paralic peat were used as sea level indicators and for 14 C dating. The shape of this curve follows the one known from the Mediterranean. This study also revealed that the present peninsula of Taman evolved out of a former archipelago.

This paper gives evidence of multiple tsunami inundation of the Sound of Lefkada (NW Greece) since the mid-Holocene based on the analysis of sediment cores by means of geomorphological, sedimentological, geochemical, micromorphological and micropalaeontological methods. Layers of sand, gravel and shell debris, mostly unsorted, were found intersecting autochthonous lagoonal muds of the sheltered and quiescent inner-sound environment. They are further characterized by erosional unconformities at their base, rip-up clasts from the underlying sediments, fining upward sequences and an upward increase in sorting. The coarse grained high energy deposits include macro- and microfaunal remains typical of open-marine, partly even deep-water conditions which underlines their allochthonous character. Several distinct event layers indicate multiple tsunami passage across the sound. Earth resistivity measurements and vibracore transects revealed that the entire sound has been affected by catastrophic wave events. Thin sections of tsunami-influenced sediments found in lateral parts of the sound show a mixture of marine, lagoonal and terrigenous material. The inner Sound of Lefkada, well protected against storms, thus represents an excellent trap for tsunamigenic deposits. A preliminary local tsunami geochronology is based on 9 radiocarbon dates and diagnostic ceramic fragments. Several early tsunami impacts hit the sound between the 6th and 3rd millennium BC. Younger events seem to be consistent with tsunami landfalls that hit adjacent areas around 1000 cal BC, 395–247 cal BC as well as in Roman and medieval times. Vibracore data document an isthmus-like shallow-water environment which existed in the central sound and which was repeatedly inundated by tsunami wave action. Multiple tsunami passage eroded a natural channel which, we suggest, is the precursor of the famous waterway excavated by the Corinthians in the 7th century BC. Based on historical data, it is concluded that the navigable channel across the sound was repeatedly choked with sediments by tsunamigenic inundation during the following centuries. This study reveals a high tsunami risk for the Sound of Lefkada with at least one strong event in every 500–1000 years.

This paper presents, for the first time, detailed geomorphological, sedimentological, geoarchaeological, geophysical and geochemical evidence of a strong tsunami impact on the Bay of Aghios Nikolaos and its environs (NW Greece) during Classical–Hellenistic times. Tsunamigenically dislocated beachrock slabs found on top of the Santa Maura beach ridge complex are closely interrelated to adjacent coarse-grained washover fan deposits encountered in vibracores and detected by earth resistivity measurements. Based on detailed topographic surveys and geomorphometric investigations, it was possible to localize areas of high intensity overflow. Underwater studies revealed that the central and northern parts of the former Plaka beach ridge were completely destroyed by tsunami impact. Loose littoral deposits were flushed into the Bay of Aghios Nikolaos and mega blocks of the underlying beachrock structure were dislocated landwards. Tsunami landfall occurred all along the eastern and northern shores of the bay where deposits, partly weathered and associated to archaeological findings, were found. Runup was estimated to minimum values between 2–3 m and 4–6 m a.s.l. Crosschecking the results of radiocarbon analyses with archaeological ages from five sites allowed to date the strong tsunami event to the time period between 395 cal BC and 247 cal BC. Due to the funnel-like contour of the coastline, the area is extremely sensitive to tsunami events of mid to high magnitude and high frequency.

The shipsheds of the ancient seaport Oiniadai (5th-3rd cent. BC), today located in the central Acheloos River delta on top of the Trikardo hills 9 km inland, document considerable coastal changes. ...

The eastern Acheloos River delta and the Lagoon of Etoliko have undergone broad environmental changes since the mid-Holocene. In this study, sedimentological, geochemical, geophysical, micromorphological, computer tomographical, micro- and macrofaunal, and archaeobotanical methods were applied to determine lateral and vertical facies patterns of near-coast geological archives. We present the stratigraphic sequences of 13 vibracores and one 9-m-long sediment core from the Lagoon of Etoliko. Geochronology was based on 28 radiocarbon dates. Sea-level fluctuations were detected by means of sedimentological sea-level markers. The relative sea level rose from 12.70 m below sea level (b.s.l.) at 6150 cal BC to 7.90 m b.s.l. by 4750 cal BC and 2.60 m b.s.l. by 500 cal BC. The maximum rate of rise occurred until 5550 cal BC, and the lowest, between Helladic and Byzantine times. Delta growth clearly increased after the relative sea-level rise decelerated around 5500 cal BC. Palaeogeographical maps for diff...

This study presents relative sea level (RSL) curves for seven coastal areas in Akarnania and the northwestern Peloponnese (NW Greece) since the mid-Holocene. RSL fluctuations are deduced from 48 14C-AMS dated sedimentological sea level markers from 27 vibracores drilled in near-coast geological archives as well as from six geoarchaeological sea level indicators of known ages. Seven palaeo sea level curves including uncertainty bands are reconstructed for a coastal zone spanning a distance of 150 km. Considerable intra-regional differences in sea level evolution exist. These differences are mainly due to tectonic reasons. In general, RSL in northwestern Greece has never been higher than today. Rates of local sea level rise were highest until 5500–5000 cal BC (up to 12.3 m/ka) and lowest during 4000–500 cal BC (0.2–1.4 m/ka). During the past 2500 or so years, RSL has accelerated anew (0.7–2.7 m/ka). Calculating differences between local mean sea level curves provides quantitative information on intra-regional differences of tectonic activity. The coastal plains of Palairos and Elis show signs of uplift, whereas the Mytikas and Boukka plains are strongly subsiding. Compared to other areas of the eastern Mediterranean, northwestern Greece has been subject to significant net long-term subsidence. Regional tectonic events (RTEs) were detected for the time around 4000, 2500, 500 and 250 cal BC as well as around 250 and 1250 cal AD. RTEs are characterized by changes of uplift/subsidence rates or by the redirection of local tectonic movements. The question if some of the RTEs were of a supra-regional nature is still open. From a geodynamic point of view, the results presented show that Akarnania's southwestern fringe is being downwarped while the tectonic block as a whole is moving towards the southwest. Strongest subsidence rates are observed for central Akarnania. At Akarnania's fringes, subsidence is reduced by the influence of strong uplift of adjacent areas such as around Preveza and the northern Peloponnese.

This paper presents geomorphological, sedimentological and geoarchaeological evidence of multiple tsunami impacts on the Aktio headland (NW Greece). Numerous vibracores revealed high energy event deposits most of which were accumulated on terrestrial sites on top of erosional unconformities. The tsunami sediments, up to 3 m thick, mostly consist of middle to coarse sand and include gravel and marine shell fragments. Both badly sorted and well sorted, laminated event deposits were observed. In several places, an intersecting palaeosol unit documents repeated tsunamigenic influence after a phase of weathering and soil formation. Underwater studies offshore Aktio headland showed that the Plaka palaeo beach ridges, including its beachrock base, out of beachrock was destroyed by tsunamigenic wave activity. Dislocated beachrock fragments with a maximum diameter of 60 cm were encountered on Aktio headland up to 2.5 km to the west of the in-situ beachrock unit in elevations up to 3.15 m a.s.l.A series of 14C-AMS dates and diagnostic ceramic fragments found in vibracores allow to reconstruct several tsunami landfalls. Around 2870-2350 cal BC, a major event hit the entire headland. Parts of the study area were probably affected by further tsunamis around 1000 cal BC and 300 cal BC which are known to have hit the adjacent Lefkada coastal zone. A mega tsunami struck the Aktio headland around 840 cal AD. The minimum height of the tsunami surge is estimated at 6m. Further tsunami landfalls occurred during the last 700 or so years. The results document an extraordinarily high tsunami risk for the study area. Cet article présente les impacts géomorphologiques, sédimentologiques et géoarchéologiques de plusieurs tsunamis qui ont affecté le cap d’Aktio (golfe Ambracien, Grèce nord-occidentale). Nos carottages ont mis en évidence des dépôts marins transgressifs, d’une épaisseur maximale de trois mètres, caractérisés par des sables grossiers, des graviers et des coquilles marines remaniées. Par endroit, un paléosol témoigne de deux évènements de haute énergie différents. Des prospections sous-marines ont aussi mis en évidence le démantèlement de dalles de beachrock. Ces blocs, d’un diamètre maximal de 60 cm, ont été retrouvés jusqu’à 2,5 km de la ligne de rivage actuelle et jusqu’à plus de 3mètres au-dessus du niveau marin actuel. Par datation radiocarbone, nous mettons en évidence un tsunami important vers 2870-2350 cal BC et plusieurs autres évènements entre 1000 et 300 cal BC. Un tsunami exceptionnel a frappé le cap d’Aktio vers 840 cal. AD. La hauteur atteinte par le tsunami est estimée à 6 m au dessus du niveau marin actuel. Ces résultats mettent en évidence l’importance des risques liés aux tsunamis dans ce secteur littoral.

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 5500 cal BC reaching approx. 1.1 km inland. The lagoon as well as the coastal lake had their largest dimensions around 4500 cal BC indicating a more humid climatic period. In the course of a long-lasting regression, an asymmetric sedimentation pattern developed. Around 2500 cal 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 500 cal BC the coastline lay about 200 m 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 12.50 m b.s.l. at 6200 cal BC via 2.20 m b.s.l. at 500 cal 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.

Sediments from the Palairos coastal plain (Akarnania, northwest Greece) were studied to establish paleogeographical scenarios of Holocene landscape evolution. Near coast vibracore profiles revealed regressive sedimentary sequences, the base of which is dominated by marine sand and/or lagoonal mud. The middle and upper parts of the sequences are made up of lacustrine mud and fine- to coarse-grained alluvial deposits reflecting the increased activity of torrential river systems. In the southern plain, marine sediments of the maximum incursion of the Ionian Sea were found 1 km inland and date from the seventh millennium B.C. This proves that the Lake Voulkaria in the northern plain does not represent the remains of a former marine embayment. Subsequently, a large lagoon developed and existed until the fourth millennium B.C. The central plain was mainly exposed to subaerial conditions when man started to colonize the area in the seventh millennium B.C. In the fifth millennium B.C., the Palairos lagoon turned into a freshwater lake. When ancient Palairos was founded in the 6th century B.C., shallow lakes and swamps dominated the southern and central parts of the plain. At that time, a narrow canal-like connection between the Bay of Palairos-Pogonia and the Lake Voulkaria existed and was possibly used as a slipway for ships. During the last 4000 years, the Palairos plain experienced strong input of fluvial sediments which finally filled up the coastal lake as well as the swampy grounds.

This paper presents evidence of multiple tsunami impact on the Bay of Palairos-Pogonia, NW Greece, during the Holocene based on detailed geo-scientific studies. Altogether, 41 vibracores were drilled to detect high-energy influence in the stratigraphical record. Layers of coarse-grained allochthonous marine deposits were found intersecting autochthonous fine-grained back beach sediments in the Palairos coastal plain, on top of beach or marly bedrock units at Pogonia beach and along the Pogonia cliff section. High-energy deposits are associated with specific sedimentary structures such as fining upward sequences, rip up-clasts, basal erosional contact, bi- to multimodal grain size distribution, lamination, and co-existence of both well rounded and angular, sharply edged components, all of them typical of tsunami impact. Macro- and microfaunal analyses revealed tsunami-related input of numerous ex situ marine species and mostly angular shell debris into quiescent fresh- to brackish water environments by high-energy and long-distance transport. Geophysical methods helped to find subsurface structures and to seize the lateral extent of tsunami layers. Ca–Fe ratios derived from XRF measurements were used to trace tsunami influence inland. Most important is the widespread spatial distribution of the tsunamites with a lateral extent between 70 m at the Pogonia cliff section, 200 m at Pogonia beach, and 1 km in the central Palairos plain, and overall tendencies of fining and thinning towards inland. Highest elevations of tsunamites were found around Pogonia village at ca. 7.5 m a.s.l. Vibracore data give evidence that the overall coastal evolution has been strongly affected, locally even controlled by multiple high-energy impact. A conspicuous geoarchaeological tsunamite, up to 1.5 m thick, was found at Pogonia cliff consisting of mixed marine (sand, pebbles, bio-erosively altered stones, shell debris, foraminifers) and terrigenous material (abundant ceramic fragments, bones, building material). It is directly associated with the submerged remains of an ancient mole which was destroyed and its building material partly dislocated by the same event. Dating of tsunamites was accomplished by archaeological age determination of diagnostic sherds and by radiocarbon and luminescence dating techniques. Strong tsunami events were dated to the beginning of the 6th, the mid-5th, the 4th/3rd and the late 2nd millennia BC as well as to the 4th/3rd century BC. On a regional scale, the recurrence interval for large events is ca. 500–1000 years. At least twice during the late Holocene, the Palairos coastal plain was flooded quasi-contemporaneously from both the northern and southern side.

L’ancienne cité d’Oiniadai se localise au sommet des collines de Trikardo au cœur du delta de l’Acheloos au nord-ouest de la Grèce (Bousquet, 1976). Ce site est de nos jours éloigné de neuf kilomètres du rivage actuel, alors que la présence de cales de halage, datées entre le cinquième et le troisième siècle avant Jésus-Christ témoignent d’une relation avec la mer Ionienne durant l’Antiquité (Philippson, 1958 ; Villas, 1984 ; Bousquet et al., 1987 ; Kolonas, 1992 ; Fouache et al., 2005 ; Vött et al., 2004). Cet article analyse la localisation successive des ports antiques de cette ancienne île ainsi que les principaux changements environnementaux qui ont affecté le delta de l’Acheloos depuis environ 6 000 ans. Les échantillons de quinze carottages ont été analysés du point de vue sédimentologique, géochimique, faunistique, palynologique et géo-chronologique (23 datations au radiocarbone et détermination des céramiques). Ces analyses à haute résolution ont aussi été croisées avec l’étude tomographique du sous-sol. Nos données montrent que, à partir de 3 000 ans avant Jésus-Christ (période helladique ancienne), un port était présent dans le secteur lagunaire au sud-est de l’ancienne île. Par comparaison, des flux hydriques importants à partir de 1 300-1 000 avant Jésus-Christ (période mycénienne, âge du bronze) ont favorisé un ralentissement du colmatage du port nord et de la baie de la nécropole. Cette phase a été la plus favorable à l’établissement d’un port protégé et en eau douce entre 1 000 et 100 avant Jésus-Christ. Durant les périodes classique, hellénistique et romaine, quand les cales de halages étaient fonctionnelles, le bassin nord communiquait donc avec la mer par l’intermédiaire d’une lagune. La baie de la nécropole était aussi un abri côtier favorable. Aux époques romaine et byzantine, un port fluvial était localisé le long d’un méandre de l’Acheloos. Dans l’état actuel de nos connaissances, nous n’avons pas pu démontrer la présence d’un port maritime le long des rivages de l’ancienne île de Trikardo. Ce site représente ainsi l’archétype d’un avant-port fluvial au cœur d’un système deltaïque, milieu paralique à la fois protégé par les lagunes et en relation rapide avec le plan d’eau marin. Ancient Oiniadai lies on top of the Trikardo hills in the centre of the Acheloos River delta (NW Greece) at a distance of 9 km from the present coast. Its shipsheds testify to a former connection with the Ionian Sea. This paper focuses on the harbours of the former island and their palaeoenvironmental changes during the past millennia. Sedimentological, geochemical, micro- and macrofaunal and palynological analyses of sediment samples from 15 vibracores as well as detailed earth resistivity tomography were carried out. A geochronology of environmental changes was established using 23 14C AMS dates and relative age determinations of ceramic fragments. Based on sedimentary and archaeological evidence, it was found that around 3000 cal yr BC, during early Helladic times, a harbour existed on the swampy lagoonal shore in the southeast. High river water inflow into the northern embayment and the necropolis bay started at 1300–1000 cal yr BC, during Mycenaean times, resulting in a decrease of the siltation of the lagoon rates and inducing ideal anchoring conditions. During Classical-Hellenistic to Roman times – when the shipsheds were in use – the northern harbour experienced ongoing water inflow from the Acheloos River and communicated with the sea via a lagoon. The necropolis bay was also a favourable harbour site. During Roman to Byzantine times, a river harbour existed near a palaeo-Acheloos meander flowing by the southeastern fringe of Trikardo. No sedimentary evidence was found that the island ever had a harbour at the seafront. Trikardo, throughout the millennia, represented an excellent terrestrial outpost amidst a low lying coastal zone, well protected by the almost impenetrable lagoonal and marshy grounds and, at the same time, providing rapid access to the sea.

This paper presents scenarios for the evolution of selected deltas in the eastern Mediterranean during the last millennia. New concepts of spatial and temporal evolution of deltas are presented based on three case studies and the use of a geoarchaeological approach – combining sedimentological facies studies and geomorphological evidence with information from written records and archaeological sources. The siltation of the seaport Ephesus (W Turkey) was associated with the progressive delta and floodplain growth of the Küçük Menderes (Kaystros) and its tributaries. Ancient Troia (W Turkey) faced the advancing Karamenderes (Scamander) and Dümrek (Simois) river deltas, and this worsened the city’s strategic position. For both case studies palaeogeographical maps are presented. They lead to new scenarios for delta and floodplain evolution which differ significantly from previous interpretations. The third case study deals with the progradation of the Acheloos delta and the location of the ancient Akarnanian seaport Oiniadai (NW Greece). For the first time, we show evidence for the younger phase of delta growth, based on geological and geochronological data. A detailed picture of the environment is developed for the time when the famous shipsheds of Oiniadai were used, whilst the model casts new light on the reasons for the final abandonment of the city. Nous présentons l’évolution paléogéographique de trois deltas de Méditerranée orientale, qui combine l’analyse des faciès sédimentologiques, des dynamiques géomorphologiques et des sources historiques et archéologiques. L’envasement du port antique d’Ephèse (W Turquie) s’explique par la progradation deltaïque du Menderes (Kaystros). Le site de Troie (W Turquie) a lui aussi subi un enclavement par avancé des deltas du Karamenderes (Scamander) et du Dümrek (Simois). Les reconstitutions paléogéographiques proposées diffèrent sensiblement des publications précédentes. La troisième étude de cas présente le port antique d’Oiniadai dans le delta de l’Acheloos (Grèce). Pour la première fois, nous avons pu dater la phase d’initiation de la progradation deltaïque et tenter d’expliquer les raisons du déclin et de l’abandon de la cité et du port.