PRELIMINARY RESULTS REGARDING THE ROCK FALLS OF DECEMBER 17, 2009 AT TEMPI, GREECE

On December 17, 2009, a large size rock fall generated at the area of Tempi, Central Greece causing one casualty. In particular, a large block was detached from a high of 70 meters and started to roll downslope and gradually became a rock slide. About 120 tones of rock material moved downward to the road resulting to the close of the national road. Few days after the slope failure, a field survey organized by the Department of Geology, AUTH took place in order to evaluate the rock fall hazard in the area and to define the triggering causal factors. As an outcome, we concluded that the heavily broken rock mass and the heavy rain-falls, of the previous days, contribute significantly to the generation of the slope failure. The rocky slope was limited stable and the high joint water pressure caused the failure of the slope

Yria (western Naxos island, Greece): Sea level changes in upper holocene and palaeogeographical reconstruction

The Saint Georgios coastal zone, located at the W coast of Naxos, the largest island of the Central Aegean Sea, was investigated in order to determine the palaeo-geography, sea level changes and their effect to the palaeo-environment of western Naxos island and to human activity. Detailed geomorphological mapping, study of micropaleontological and sedimentological characteristics and dating analyses of the Late Holocene of St. Georgios coastal zone were conducted. To obtain information about the Holocene stratigraphy under the recent alluvial cover, three boreholes followed the detailed geomorphological mapping. Microfaunal analysis took place and five samples of plants, shells, peat and charred material were also collected from several layers of the sedimentary sequence and were dated using AMS and conventional radiocarbon techniques providing temporal control of the sediments. The sea-land interactions during Upper Holocene, in relation to the eustatic sea level oscillations, as well as the géomorphologie observations and analysis on deposited sediments, aims to reveal the palaeo-geographic evolution of the landscape and its impact on the archaeological sites. Sea level rise along with sea-land interactions to the landscape evolution and the transgression of sea in 6144 BP have been verified. © 2010 Lavoisier SAS. All rights reserved

A multi-proxy approach for reconstructing environmental dynamics since the mid Holocene in Lake Ismarida (Thrace, N. Greece)

The paleoenvironmental evolution of Lake Ismarida in Thrace (Northern Greece) is revealed by the combined lithological, micropaleontological (benthic foraminifera, pollen and NPPS), molluscan analyses, magnetic susceptibility measurement and radiocarbon dating of a 5.8-m long sediment core. The mid Holocene evolution of the lake area is evidenced by the documentation of four sedimentary Units in the core ISMR-2, corresponding to four distinct evolutionary stages: (1) during ∼5500-3500 cal yr BP the lake area was a shallow marine environment characterized by an Ammonia beccarii, small rotaliids, miliolids, Bittium reticulatum and Veneridae spp. assemblage, marine dinoflagellate cysts, and low magnetic susceptibility values; (2) during ∼3500-3000 cal BP the environment is gradually tending to more isolated conditions forming an open lagoon, characterized by marine and euryhaline fauna and low magnetic susceptibility values; (3) during 3000 cal yr BP, the open lagoon presented a transition to an oligohaline inner lagoon, characterized by an Ammonia tepida, Haynesina germanica, Aubignyna perlucida, Pirenella conica, Cerastoderma glaucum and Abra spp. assemblage, sedges and aquatic vegetation. This restricted, entirely isolated from the sea inner lagoon could be definitely used as the landmark of the Lake Ismaris from Heorodotus, while describing the march of Xerxes through Thrace in 480 B.C.; (4) since ∼2000 cal yr BP to the present, the Lake Ismarida is formed, characterized by fresh-water indicators and aquatic pollen, Pseudoschizaea and high magnetic susceptibility values. Finally, the progradation of the Filiouris River deltaic deposits resulted to a 4 km wide deltaic plain between Lake Ismarida and the nowadays coastline. Pollen assemblages record the dominance of a rather rich deciduous forest in the area with traces of human presence in the lower part of the sequence, whereas the opening of the plant landscape under the increasing human pressure is evidenced after ∼ 3000 cal yr BP. Finally, an open vegetation pattern, contemporaneous with the retreat of forest vegetation, is evidenced in the area already before 2000 cal yr BP. © 2020 Elsevier Masson SA

Holocene palaeogeographical reconstruction of the western part of Naxos island (Greece)

Naxos Island is situated in the Cycladic plateau (middle Aegean Sea) and consists of concaved beach zones separated by small headlands. This study investigates the diachronic palaeo-shoreline shift due to the sea level change and its effect to the palaeo-environmental evolution of the western coastal part of Naxos Island during the Late Holocene. For this purpose, six boreholes were drilled and dated using radiocarbon techniques. The associated geomorphological, sedimentological and paleontological investigation concluded that during Late Holocene, the embayments of Naxos western coastal part were frequently exposed, and their communication with the sea was not perennial. The coastal area was wider with many active lagoons and embayment changing from shallow marine environment to coastal environment frequently alternating to brackish mesohaline one. The former sea-level position in western Naxos island should be between -1.5 m and -2 m during the last 2000 years, which may partly reflect eustatic processes and partly a gradual or coseismic land subsidence. © 2011

Benthic foraminiferal evidence and paleoenvironmental evolution of Holocene coastal plains in the Aegean Sea (Greece)

Benthic foraminiferal composition of sedimentary successions during the last 7500 years, was investigated from boreholes drilled in three rather tectonically stable coastal areas of the Aegean Sea (Alykes Kitros, Lafrouda Thrace and Vravron Attica). The quantitative analysis of foraminiferal fauna enabled separation into two different groups that are supported by the analysis of modern benthic foraminiferal communities in the studied sites. Group A consists of Ammonia tepida and Haynesina germanica (closed lagoon assemblage), whereas the most common species of Group B (open lagoon assemblage) are Aubignyna perlucida, miliolids, Elphidium spp. and Ammonia spp. The foraminiferal composition integrated with radiometric dating provides information on Holocene paleoenvironmental changes in the studied coastal plains, related to sea-land interaction. Alykes Kitros and Lafrouda Thrace boreholes show a similar trend, with an open lagoonal fauna in the lower part, transitional upwards to closed lagoonal conditions. This environmental change has taken place after 6500 cal BP in Alykes Kitros and around 3000 cal BP at Lafrouda Thrace. The benthic communities of Vravron Attica borehole sediments seem to represent continuously an open lagoon/shallow marine environment from 4700 to 400 cal BP. © 2011 Elsevier Ltd and INQUA

Holocene palaeogeographical reconstruction and relative sea-level changes in the southeastern part of the island of Samos (Greece)

In this paper, we focus on the southeastern coastal zone of the island of Samos (east-central Aegean Sea), in order to reconstruct the evolution of coastal landscapes and the relative sea-level changes during the late Holocene. We use geomorphological mapping, sedimentological and palaeontological proxies of late Holocene coastal deposits from two lagoon environments. We further compare our results with previously published sea-level data and we show that the southeastern part of Samos was characterized by a subsidence trend at least during the late Holocene, with RSL rise rates of ∼0.8 mm/yr. Our study additionally highlights that local-scale tectonics is responsible for the evolution of the coastal zone of Samos. © 2019 Académie des science

Morphotectonic control on drainage network evolution in the Perachora Peninsula, Greece

In tectonically active areas drainage systems are often influenced by the type, geometry, and recent activity of regional and local faults. In the Perachora peninsula, eastern Gulf of Corinth (Greece), most drainage networks are influenced by neotectonic processes and eustasy. Two major east-west trending fluvial systems (Perachora and Pissia) in the southwestern part of the peninsula are affected by faults of similar orientation. Detailed geomorphological mapping was performed focusing on knickpoints, gorges, planation and depositional surfaces, alluvial fans and talus cones. Longitudinal river profiles and hypsometric curves of their basins were constructed utilizing GIS technology. The two drainage systems exhibit opposite network asymmetries. The Pissia network is well developed south of the main channel while the Perachora extends to the north. The analysis of the longitudinal profiles of the main stream channels denotes that they exhibit different evolutionary trends. The Pissia stream has a "transverse" drainage crossing the active Loutraki fault, while the Perachora stream has a "parallel" evolution as it has the same orientation as the Loutraki fault. The drainage system of Pissia is much older than the Perachora as a large part of the latter was underwater in Late Pleistocene times. The combination of eustacy and vertical tectonic movements has led to the development of four marine terraces corresponding to previous high sea-level stands during Oxygen Isotope Stages (OIS) 5e, 7e, 9c and 11c. Following the analysis of the longitudinal profiles and the hypsometric curves two depositional surfaces were verified at Perachora village. The first surface at 280-360 m and the second one between 120 and 160 m are probably related to marine terraces 11c and 7e respectively. The development of the present drainage systems of Perachora and Pissia in the Late Quaternary depends mostly on the fault tectonism of the two main offshore fault systems of Xylokastro and Loutraki resulting in the uplift of marine terraces to heights of more than 300 m, but also due to the inland faults (Pissia and Alepochori) which created depositional surfaces and knickpoints. Sea-level changes have played a secondary role in the development of the drainage systems. © 2008 Elsevier B.V. All rights reserved

Paleoenvironmental evolution and prehistoric human environment, in the embayment of Palamari (Skyros Island, Greece) during Middle-Late Holocene

Palamari Bay is located on the northeastern coast of Skyros Island (Sporades Islands, Aegean Sea). At the northern edge of the bay a fortified prehistoric settlement is found, dated between 2800 and 1700 BC (Early Bronze Age II-Middle Bronze Age I). Detailed geomorphological mapping of the coastal alluvial plain and paleontological, micropaleontological, palynological, sedimentological and micromorphological studies of the Holocene coastal deposits have been conducted in order to reconstruct the palaeoenvironment and the landscape evolution of the broader area of Palamari Bay. Three main sedimentary units were recognized (A, B and C, from oldest to youngest). The lowermost sedimentary unit A, deposited between before 7500 and 3500 cal BP, consists of sediment deposited from high to moderate energy fresh water flows with some suspended load fallout in established water bodies. The microfauna indicates a shallow fresh water environment. However, a tendency to oligohaline conditions was established gradually. During the same period, the Palamari area was characterized by open mixed deciduous forests that gradually retreated as a possible consequence of the intensification of anthropic activity, associated with the settlement of Palamari. Indications of cultivating and grazing activities in the vicinity of the lagoon were identified, pointing to a strong human presence since the Neolithic. Between about 6000 and 3500 cal BP, the embayment was a lagoon southeasterly connected to the sea, therefore sheltered and protected from northeastern winds. The overlying unit B (ca. 3500-800 cal BP) is characterized by the dominance of brackish water microfauna, indicating a brackish stagnant shallow water depositional environment, which was periodically supplied with fresh water from the surrounding springs. As the result of the continuous sea-level rise during the Late Holocene, part of the northern headland was submerged. The decline of the Palamari settlement at the time of the establishment of Unit B might be related to the observed changes that rendered the embayment a restricted body of water. The uppermost sedimentary unit C corresponds to a backshore environment dominated by aeolian activity modified by fluvial processes. © 2009 Elsevier Ltd and INQUA