Matthieu Ghilardi

Contribution on the Holocene Reconstruction of Thessaloniki Coastal Plain, Greece

Abstract 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 sealevel 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.

Geomorphologic and paleoclimatic evidence of Holocene glaciation on Mount Olympus, Greece

This study investigates the possibility of Holocene glaciation on Mount Olympus (Greece) with a respective local temperature–precipitation equilibrium line altitude (TP-ELA) at c. 2200 m a.s.l., based on geomorphologic and paleoclimatic evidence. At present, the local TP-ELA is situated above the mountain’s summit (c. 2918 m a.s.l.), but permanent snowfields and ice bodies survive within Megala Kazania cirque between c. 2400 and c. 2300 m a.s.l., because of the cirque’s maritime setting that results from its close proximity (c. 18 km) to the Aegean Sea and of the local topographical controls. The snow and ice bodies occupied a considerably larger area and attained a stabilization phase between AD 1960 and 1980, also manifested from aerial photographs, a period characterized by increased winter precipitation (Pw) with subsequent TP-ELA depression to c. 2410 m a.s.l. Mid- to late-20th-century Pw and TP-ELA variations exhibit negative correlations with the winter North Atlantic Oscillation index (NAOw) at annual and multidecadal (30 years) timescales. Late Holocene (AD 1680–1860) reconstructed summer mean temperatures were lower by Ts < 1.1°C in relation to the reference period between AD 1960 and 1980 and were also superimposed to negative NAOw phases, thus bracketing this time interval as a favorable one to glacial formation and/or advance. Millennial-scale annual precipitation reconstructions at the hypothesized TP-ELA (c. 2200 m a.s.l.) point the period between 8 and 4 kyr BP as another glacier-friendly candidate. The mid-Holocene rather simplistic sequence of potential glacial advance phase was disturbed by short-lived cold climatic deteriorations, well-documented over the northern Aegean region that may partly explain the multicrested shape of the highest (c. 2200 m a.s.l.) morainic complex of Megala Kazania cirque.

Late Pleistocene to Mid Holocene landscape reconstruction in the western part of the Thessaloniki Plain (Greece): evidence for environmental changes, and their consequences for the settlement history

This study presents new data from four boreholes in order to investigate the palaeoenvironmental changes and landscape configuration from the Late Pleistocene to the Mid-Holocene in the western part of the Thessaloniki plain. Palaeoenvironmental and archaeological records from northern Greece document the occurrence of significant landscape changes during the Holocene. While traces of human occupation are scarce in the western Thessaloniki plain during the transition from the Late Pleistocene (Lateglacial) to the Holocene (Mesolithic period), the climatic and environmental changes involved significant and abrupt impacts on surface processes. Recently published results indicated that palaeoenvironmental transitions in the area influenced the human occupation from the early Holocene (8000/7800 cal. BP) to recent times. However, the Late Pleistocene landscape configuration has not been clearly established. A new sequence is used for analyses of grain size, loss-on-ignition, carbonate content and rock magnetic properties. In addition, a series of 6 new AMS dates from the area provide a precise chronostratigraphy. The synthesis of the environmental proxies reveals distinct palaeoenvironmental changes within a well-constructed chronostratigraphic framework of more than 10k years, which is the longest sedimentary sequence reported for central Macedonia. The Late Pleistocene subsurface occurs at ~9 m depth and clearly indicates the presence of a large alluvial fan deposited by the Aliakmon River during the Younger Dryas (12.7k-11.7kyr BP). The abrupt transition to Early Holocene sediments reveals that a significant influx of fresh water generated a limnic sedimentary environment under detrital and human stress, from pre- to post-reforestation period in the area. Anthropogenic influence is also significantly recorded mainly by the magnetic properties of the lacustrine sediments after 9000 cal. BP. From Neolithic times to the present day, the study area was periodically occupied by a freshwater lake while palaeo-soils are clearly identified by anthropogenic activities and are dated from the Early Neolithic period.

Environmental imprints of landscape evolution and human activities during the Holocene in a small catchment of the Calanques Massif (Cassis, southern France)

This paper is based on a multidisciplinary study using both paleoenvironmental methods (biological, sedimentological, magnetic and geochemical) and archaeological data in order to characterize landscape and hydrological network changes as well as human impact on a littoral catchment in the Western Mediterranean area. Sedimentary records obtained around a coastal alluvial plain (Cassis, Southeastern France) reveal local environmental changes and human activities since the Neolithic (ca. 6000 cal. BP). Anthropogenic impact is already noticeable in the earliest record, and we follow its evolution through time. According to biological markers, the Holocene landscape of the Calanques is dominated by a mosaic of open herbaceous formations partly generated by human activity. The prevalence of Cernuella virgata in malacofauna successions and of coprophilous fungal spores in the pollen record testifies to the spread of agro-pastoral activities. Two increases of anthropogenic impact are highlighted during the Roman (ca. 2000 cal. BP) and Modern (from ca. 1450 to today) periods. Lead isotope analyses indicate an anthropogenic release of lead, possibly originating from the Greek Cyclades (ca. 2000 cal. BP). Hydrographic and agricultural work is also enhanced during the Roman period. Magnetic parameters and lead isotopes indicate that the Modern anthropogenic impact may be associated with high temperature activities (e.g. lime kiln, fossil fuel).

The Holocene fluvial history of the Tremithos river (south central Cyprus) and its linkage to archaeological records

Abstract This study aims to reconstruct the Holocene fluvial history of the Tremithos river, south central Cyprus and examine linkages to regional and local archaeological records. Three stratigraphic profiles (Sp1, Sp2 and Sp3) located in the lower valley have been investigated using sedimentology and magnetic parameters. The 14C dating of 10 samples reveals mid-Holocene ages for Sp1 and Sp2, while the upper most part of Sp3 can be attributed to the early to mid-Holocene. Two main phases of vertical accretion have been recognised: the first, recorded in the lower most part of Sp3, could not be dated but might relate to the late Glacial period. It is not associated with any archaeological artefacts. The second, recorded in all profiles, dating from ca. 5000 to ca. cal 2800 BC, spans the Late Neolithic Sotira (cal 4800/4000 BC) and Late Chalcolithic (cal 2900–2500 BC) cultures. The sediments of Sp1 and Sp2 are up to 8–10 m thick and mainly composed of fine material. However, an intercalated phase of coarse sediment has been identified at the beginning of the third millennium BC, indicating a sudden change in river dynamics, potentially associated with the 5.2 ka rapid climate change regional event. Typical mid-Chalcolithic (ca. cal 3300–3050 BC) ceramics found in a palaeosol in Sp2 indicate for the first time human occupation of the Tremithos river terraces. Two other palaeosols have also been recognised in Sp3 and radiocarbon dated to ca. cal 5600–4100 BC and ca. cal 2900–2600 BC, respectively. These results make it possible to propose a palaeogeographic reconstruction of the Holocene evolution in the Tremithos valley and to make a preliminary assessment of the relative roles of tectonics, climate and anthropogenic forcing.

Clastic sedimentary features of beachrocks and their palaeo-environmental significance: comparison of past and modern coastal regimes

Clastic sedimentary features of beachrocks and unconsolidated deposits of parent beaches were investigated along the northern Aegean coastline (Greece) to assess their suitability in palaeo-environmental reconstruction. Twelve paired datasets were collected in the Thermaikos, Toroneos, Siggitikos and Ierissos gulfs of the Chalkidiki Peninsula, the adjoining Kavala Gulf and Thassos Island, comprising beachrock cores and companion beach subsurface sediments. Particle size analyses based on univariate and bivariate statistics suggest that, during the time period of beachrock formation, depositional conditions differed distinctly from those of the modern parent beaches. The results imply difference of maturity level of beach evolution from the time of cementation (coarser materials-early stage of beach formation) to modern situation (finer materials-reworked and ‘mature’ beach sediments). Furthermore, the findings indicate increasing coastal protection due to beachrock exposure in the modern swash zone. In conclusion, it is suggested that textural analysis of beachrocks in comparison with unconsolidated sediments of the parent beach might provide information regarding differences of coastal depositional regimes and future research could focus on specific-layer analysis and comparison.

Reconstructing Mid-to Recent Holocene palaeoenvironments in the vicinity of Ancient Amarynthos (Euboea Island, Greece)

This article examines the shoreline evolution and human occupation in the vicinity of the important archeological site of Amarynthos (Euboea Island, Greece) over the last six millennia. Archeological evidence indicates a continuous occupation of the site from the Bronze Age to the Roman period and the site is well-known, thanks to the existence of a sanctuary dedicated to the goddess Artemis. Based on the study of four boreholes, a paleogeographic reconstruction of the coastal landscape is proposed. Facies were determined based on mollusc identification, and sedimentology based on grain-size measurements (hand sieving for the fraction above 2 mm and LASER technique for particles below 2 mm) and loss-on-ignition. In addition, a series of 12 AMS radiocarbon dates define a reliable chronostratigraphy. Results suggest the presence of a fully marine environment from the early Holocene to ca. 2600–2400 cal. BC, which developed into a brackish environment from ca. 2600–2400 cal. BC to ca. 750 cal. BC due to the deltaic progradation of the nearby stream (Sarandapotamos River). From ca. 750 cal. BC onward, coastal swamps prevailed in the study area. Human-environmental interaction is discussed and particular attention is paid to the paleolandscape configuration of Amarynthos.

First evidence of a lake at Ancient Phaistos (Messara Plain, South-Central Crete, Greece): Reconstructing paleoenvironments and differentiating the roles of human land-use and paleoclimate from Minoan to Roman times

Phaistos was one of the most important Minoan palaces in Crete and previous studies have addressed its relationship with the paleo-seashore position during historical times. Here, we reconstruct the environmental evolution of Phaistos from Early Minoan to Roman times. Study of two stratigraphic sections and nine boreholes drilled in the westernmost part of the Messara Plain has revealed the stratigraphy of the Mid- to Late-Holocene sediments. Laboratory analyses comprise granulometry, magnetic susceptibility measurements and identification of mollusks, diatoms and pollen grains. Eighteen radiocarbon dates provide a robust chronostratigraphy. In addition, a geophysical survey (electric resistivity tomography (ERT) method) was conducted to reveal the sub-surface morphology in the coring area. The results reveal that a freshwater lake existed from ca. 2100–2000 BC to ca. 1200–1100 BC, which subsequently became swampland until ca. 700 BC. A lake retreat is identified at ca. 1200–1000 BC and can be interpreted as resulting from the 3.2 cal kyr BP rapid climate change (RCC) dry event, observed elsewhere in the Eastern Mediterranean. Subsequently, from the 7th to the 5th century BC, there was the input of detrital material and fluvial dynamics prevailed until at least Roman times. The origin of the lake and its disappearance are discussed in the context of regional climate change and local tectonic activity, without excluding possible human influences. We also reconstruct the vegetation history for the period from the Late Minoan to the Early Archaic period. Pollen analysis reveals a Mediterranean maquis landscape dominated by Olea, together with hygrophilous vegetation, and highlights a clear transition from limnic to swampy environmental conditions around 1100 BC. The pollen sequence is also important for assessing the impact of the 3.2 cal. kyr BP RCC event and for assessing the possibility of an abrupt discontinuity in human activity around Phaistos after the demise of the Minoan Civilization.