Search results for "HOLOCENE"
showing 10 items of 330 documents
The far south: the Pleistocene–Holocene transition in Nerja Cave (Andalucı́a, Spain)
2002
Abstract The archaeological site of Cueva de Nerja (Malaga, Spain) provides significant data about the bioclimatic conditions of one of the most southern European temperate regions. The bioclimatic and palaeogeographic changes that have occurred during the 20,000 years of human occupation of the site can be analysed by relating the geodynamic processes, the palaeobotany and the palaeofauna recovered from its archaeological deposits.
A HYDRAULIC CONDUCTIVITY MODEL POINTS TO POST-NEOGENE SURVIVAL OF THE MEDITERRANEAN OLIVE
2004
Research on the subfossil record and paleoecology of Olea europaea suggests a new interpretation of its history and ecology with reference to the Mediterranean climate since the Neogene. New results are based on the wood anatomy of ancient and extant Olea and a model estimating hydraulic conductance established for wild forms belonging to Olea europaea subsp. europaea. These suggest that during glacial periods wild olive populations survived in protected microenvironments, particularly riparian habitats. Thereafter, the postglacial expansion of olive associated with climatic warming took place from these refuge areas. This new evidence suggests that the continued existence of Olea in Medite…
Fire frequency during the Holocene in central Latvia, northeastern Europe
2021
Fire is today a pan-European issue and is expected to be more salient because of climate and land use changes. Even though natural and anthropogenic fires have shaped forest composition and landscape characteristics since the last glacial retreat from northeastern Europe, fire frequency is an understudied topic. To address this issue, we analysed macroscopic charcoal (>160 μm) from two sediment sequences located in the central and littoral parts of Lake Bricu (central Latvia) revealing the fire frequency during the Holocene. The chronology of the analysed sediment sequences is based on spheroidal fly-ash carbonaceous particles and accelerator mass spectrometry radiocarbon dating. Macroscop…
The arid–humid transition in the Sahara and the Sahel during the last deglaciation
1990
At the time of the Last Glacial Maximum, the Sahara and Sahel regions of North Africa were extremely dry. New records of rainfall show that during the subsequent deglaciation, the transition from arid to humid conditions in these regions occurred synchronously in two main steps. Comparison with other records of palaeoclimate in Europe and the North Atlantic Ocean shows that certain common factors controlled changes in ocean and atmosphere dynamics during the deglaciation.
Biochronological and paleoenvironmental interest of foraminifera lived in restricted environments: application to the study of the western Mediterran…
2002
As a consequence ofthe Flandrian transgression, numerous littoral lakes were f since roughly 6000 BP in the western Mediterranean coast. This kind of environment is colonized, among other groups, by specialized forms of foraminifera. Some species arose in the Upper Tertiary, some others in the Pleistocene and others are exclusively Holocene. Two kinds ofenvironment are proposed in the colonization: one with very low salinity waters where agglutinated test species prevail and another one with brackish waters, dominated by calcareous test species. In addition, Trichohyalus aguayoi can be considered as an acmezone within the Holocene. We propose a cenozone formed by the following assemblage: A…
Pleistocene and Holocene aeolian sediments of different location and geological history: A new insight from rounding and frosting of quartz grains
2014
Abstract Rounding and frosting of quartz grains in aeolian sediments of the known stratigraphic position and unique geological setting was explored in Finnish, Estonian, Latvian, and Polish localities and in Fuerteventura Island. The aim of the study is to characterize the variability of the spatial pattern of rounding and frosting of quartz grains in the sandy (0.5–0.8 mm) fraction and to evaluate the factors influencing it. The relationships between rounded and non-abraded, as well as matt- and shiny-type quartz grains were calculated for 159 samples and evaluated against the aeolian subenvironment, substratum and presumed age of the locations. The obtained relations do not confirm meridi…
Active tectonics along the south east offshore margin of Mt. Etna: New insights from high-resolution seismic profiles
2018
The offshore margin of Mt. Etna has been shaped by Middle Pleistocene to Holocene shortening and extension and, more recently, by gravity-related sliding of the volcanic edifice. These processes have acted contemporaneously although the gravitational component largely prevails over the tectonic one. In order to investigate this issue, we focused on the main role of active tectonics along the south-eastern offshore of Mt. Etna by means of marine high-resolution seismic data. Seismic profiles revealed post-220 ka sedimentary deposits unconformably overlaying the Lower-Middle Pleistocene Etnean clayey substratum and volcanics of the Basal Tholeiitic phase and the Timpe phase. Offshore Aci Trez…
Neolithic Human Societies and Woodlands in the North-Western Mediterranean Region: Wood and Charcoal Analysis
2017
An overview of woodland history in the north-western Mediterranean region, based on charcoal analysis (Anthracology) from Mesolithic and Neolithic sites, is proposed for the Mediterranean areas of France, Spain and Portugal. The taxonomic identification of charcoal fragments and the diachronic variations of taxa frequencies provide, for each settlement, an accurate image of the local vegetal cover. During the end of the last glaciation, beginning of the Holocene, vegetation dynamics reflects the evolution of climatic and geographic conditions. Any potential ecological impact by hunter-fisher-gatherer communities (Mesolithic) remains invisible; the same comment applies to the farming-herding…
Biogeography of the Pleistocene pleniglacial malacofaunas in Europe. Stratigraphic and climatic implications
1990
Abstract As determined by Lozek, malacological associations are significant of a particular vegetal environment. In Quaternary sequences, different types of associations are recognized which can be assimilated to the present types of malacofaunas. There are associations of grass group, of forest group and of the ecotone of these two biogeographical entities. On the European scale, in Pleistocene sequences, the interglacial faunas indicate similarly the same differences as today, being of stratigraphic interest. On the contrary, pleniglacial faunas, which are mainly preserved in the loess belt, seemed not interesting for stratigraphy since they indicate more generalized and more homogeneous …
Long-term decrease in Asian monsoon rainfall and abrupt climate change events over the past 6,700 years
2021
Significance The variability of the Asian summer monsoon (ASM) is important for the functioning of ecological and societal systems at regional to continental scales, but the long-term evolution and interannual variability of this system is not well understood. Here, we present a stable isotope–based reconstruction of ASM variability covering 4680 BCE to 2011 CE. Superimposed on a gradual drying trend, a rapid drop in mean annual precipitation (>40%) toward persistently drier conditions occurred in ∼1675 BCE. This megadrought caused regional forest deterioration and enhanced aeolian activity affecting Chinese ecosystems. We argue that this abrupt aridification starting ∼2000 BCE triggered wa…