Search results for "PROCESSES"
showing 10 items of 3831 documents
Meteorological validation of chironomids as a paleotemperature proxy using varved lake sediments
2016
In order to improve the reliability of climate models in their projections for the future, spatially and temporally detailed paleoclimate proxy data are needed. In this study, we examined annually laminated sediments from Lake Nurmijärvi (Finland) for their fossil Chironomidae assemblages over a time period with available meteorological observational data (since 1830s). In doing so, we correlated chironomid-based inferences of summer air temperatures against instrumentally measured values using two different reconstruction approaches, namely, calibration-in-space (CiS, multilake training set) and calibration-in-time (CiT, calibration of time series data against meteorological data). The re…
Palaeoenvironmental evidence for the impact of the crusades on the local and regional environment of medieval (13th–16th century) northern Latvia, ea…
2015
This paper evaluates the impact of the crusades on the landscape and environment of northern Latvia between the 13th–16th centuries (medieval Livonia). The crusades replaced tribal societies in the eastern Baltic with a religious state (Ordenstaat) run by the military orders and their allies, accompanied by significant social, cultural and economic developments. These changes have previously received little consideration in palaeoenvironmental studies of past land use in the eastern Baltic region, but are fundamental to understanding the development and expansion of a European Christian identity. Sediment cores from Lake Trikāta, located adjacent to a medieval castle and settlement, were s…
Rapid climate change during the early Holocene in western Europe and Greenland
2006
Based on microfacies analyses of seasonally laminated varved sediments from lake Holzmaar, Germany, we report evidence of decadal-to century-scale climate variability during the early Holocene. The shifts in climate are documented in the thickness variations and changes in the composition of the varves in response to subtle shifts in limnological conditions. The close similarity between the Holzmaar varve record and the GRIP oxygen isotope record during 7.4-9.0 calendar (cal.) ka suggests that the high frequency climatic variations in both regions were controlled by the same mechanism. Our more detailed studies covering the central 409-yr period (∼7.846-8.255 cal. ka, encompassing the 8.2 …
Luminescence dating of aeolian–coastal events on the Kristianstad plain, SE Sweden
2016
Aeolian–coastal sediments and landforms are excellent palaeoenvironmental archives, but chronological studies of coastal records are scarce in Sweden. In this study, we provide luminescence and radiocarbon ages of aeolian activity and coastal landscape evolution on the Kristianstad plain, SE Sweden, based on the investigations of two foredunes and two inland dunes at Åhus and Vittskövle. Additionally, we do a laboratory intercomparison of five young luminescence samples. The comparison shows a significant age difference most likely due to an instrumental difference. The equivalent dose cannot be determined accurately with the low irradiation times, and therefore, the results obtained from …
Ceramic productions and human interactions during the Early Bronze Age in northern Iberia
2021
The Early Bronze Age ceramic collection found into the caves of La Llana and El Toral III in Asturias (Spain) presents common decoration such as that found in the centre of Cantabrian Spain from the same period, which resembles others found in the Ebro Valley and Atlantic Europe. Therefore, the main objective of this study it is to identify the raw material origin and understand the pottery production process during the Early Bronze Age in the Cantabrian region. A methodological approach based on the chemical and mineralogical analysis of vessels and experimentally fired clay samples collected all over the centre of this region was developed. Furthermore, the post-depositional processes aff…
Late Quaternary coastal uplift of southwestern Sicily, central Mediterranean sea
2021
Abstract Mapping and luminescence aging of raised marine terraces and aeolian ridges along an ∼90 km coastal stretch in southwestern Sicily provide the first quantitative assessment of vertical tectonic deformation in this region, which spans the frontal part of an active thrust belt. We recognized a staircase of eleven terraces and nine related aeolian ridges. The elevation profile of terraces parallel to the coast shows a >90 km long bell-shaped pattern, onto which shorter-wavelength (∼10 km long) undulations are superimposed. Luminescence ages from terraced beach deposits and aeolian sediments constrain the position of paleoshorelines formed during MIS 5e, 7a and 7c, with a maximum uplif…
Prehistoric palaeodemographics and regional land cover change in eastern Iberia
2019
Much attention has been placed on the drivers of vegetation change on the Iberian Peninsula. While climate plays a key role in determining the species pools within different regions and exerts a strong influence on broad vegetation patterning, the role of humans, particularly during prehistory, is less clear. The aim of this paper is to assess the influence of prehistoric population change on shaping vegetation patterns in eastern Iberia and the Balearic Islands between the start of the Neolithic and the late Bronze Age. In all, 3385 radiocarbon dates have been compiled across the study area to provide a palaeodemographic proxy (radiocarbon summed probability distributions (SPDs)). Modelled…
Environmental responses of past and recent agropastoral activities on south Greenlandic ecosystems through molecular biomarkers
2016
Paleoenvironmental studies previously performed on Lake Igaliku revealed two agropastoral phases in south Greenland: the Norse settlement from AD 986 to ca. AD 1450 and the recent installation of sheep farmers, since the 1920s. To improve the knowledge of the timing and magnitude of the Greenlandic agropastoral activities, a lipid inventory was realized and compared with biological and geochemical data. During the 12th century, a major increase in deoxycholic acid (DOC) and coprophilous fungal spores revealed a maximum of herbivores. Synchronously, a minimum of the n-C29/ n-C31 alkane ratio and tree and shrub pollen and a maximum of triterpenyl acetates showed a reduction in the tree and s…
Patch-based survey methods for studying prehistoric human land-use in agriculturally modified landscapes: A case study from the Canal de Navarrés, ea…
2018
Abstract In landscapes whose surface has been modified by terracing and other agricultural land-use, the spatial and temporal patterning of prehistoric settlement can be difficult to detect using traditional, site-orientated archaeological survey methods, especially for small-scale societies. In these contexts, methods that can reveal occupational patterns at landscape scales, without the need to pinpoint specific sites of human occupation, can be especially useful. We employ a stratified, randomly selected patch-based survey strategy to examine socio-ecological dynamics from the Middle Paleolithic through Bell Beaker (Chalcolithic) periods within the Canal de Navarres, eastern Spain. We di…
Astrochronology of the Valanginian Stage from reference sections (Vocontian Basin, France) and palaeoenvironmental implications for the Weissert Even…
2013
12 pages; International audience; High-resolution gamma-ray measurements performed on five biostratigraphically well-dated reference sections from the Vocontian Basin (south-eastern France) are used to develop a new astrochronology of the Valanginian Stage and its subdivisions (i.e. ammonite and calcareous nannofossil zones and subzones). Spectral analyses show a pervasive dominance of 405-kyr eccentricity cycles with the expression of 100-kyr eccentricity, obliquity and precession. Previous rough estimates of Valanginian Stage duration ranged from 3.9 to 6.5 myr but were generally based on less reliable or indirect methods. This study provides a precise duration of 5.08 myr, tuning the ser…