Search results for "Present day"
showing 10 items of 12 documents
Palaeobiogeography of Austral echinoid faunas: a first quantitative approach
2013
Few studies have been devoted to the palaeobiogeography of Antarctic echinoids, all of them analysing and discussing distribution patterns in a qualitative way. The present work aims at exploring the evolution of palaeobiogeographic relationships of Austral echinoid faunas through four time intervals, from the Maastrichtian to the present day, using a quantitative approach: the Bootstrapped Spanning Network procedure. Analyses were successfully performed and improve our knowledge of biogeographic relationships between the different Austral regions. Biogeographic maps were produced that can be easily and intuitively discussed. Our results mostly agree with palaeobiogeographic studies perform…
The Distribution and Chronology of Trading Equipment in Present-Day Latvia in the Tenth to Thirteenth Centuries
2017
This article brings together the main research findings of recent years relating to tenth to thirteenth-century trading equipment from present-day Latvia. Finds of collapsible scales and weights from all regions of Latvia have been mapped and investigated. These include finds from archaeological sites in the Zemgale and Kurzeme regions that have previously not been extensively analysed. Issues relating to the chronology of the scales and weights are discussed. The main trade routes and the dynamics of trade contacts are determined, based on the distribution of the material in different regions. Key words: trade routes, chronology, scales, weights. DOI: http://dx.doi.org/10.15181/ab.v24i0.15…
Millstone coastal quarries of the Mediterranean: A new class of sea level indicator
2014
The coasts of Italy still preserve several remnants of coastal quarries built in antiquity, that now provide insights into the intervening sea-level changes occurred during the last millennia. In this paper, we show and discuss a new class of sea level indicator consisting of millstones carved along the rocky coast of southern Italy since 2500 BP, that are currently submerged. They were extracted from beachrocks, sandstones or similar sedimentary rocks, easier for carving by ancient carving tools. Our study focuses on 10 coastal sites located at Capo d'Orlando, Avola, and Letojanni, in Sicily; Soverato, Tropea, and Capo dell'Armi, in Calabria; Castellabate, Palinuro, and Scario, in Campania…
Present-day uplift of the European Alps: Evaluating mechanisms and models of their relative contributions
2019
Abstract Recent measurements of surface vertical displacements of the European Alps show a correlation between vertical velocities and topographic features, with widespread uplift at rates of up to ~2–2.5 mm/a in the North-Western and Central Alps, and ~1 mm/a across a continuous region from the Eastern to the South-Western Alps. Such a rock uplift rate pattern is at odds with the horizontal velocity field, characterized by shortening and crustal thickening in the Eastern Alps and very limited deformation in the Central and Western Alps. Proposed mechanisms of rock uplift rate include isostatic response to the last deglaciation, long-term erosion, detachment of the Western Alpine slab, as w…
Back to Gondwanaland: can ancient vicariance explain (some) Indian Ocean disjunct plant distributions?
2015
Oceans, or other wide expanses of inhospitable environment, interrupt present day distributions of many plant groups. Using molecular dating techniques, generally incorporating fossil evidence, we can estimate when such distributions originated. Numerous dating analyses have recently precipitated a paradigm shift in the general explanations for the phenomenon, away from older geological causes, such as continental drift, in favour of more recent, long-distance dispersal (LDD). For example, the ‘Gondwanan vicariance’ scenario has been dismissed in various studies of Indian Ocean disjunct distributions. We used the gentian tribe Exaceae to reassess this scenario using molecular dating with mi…
Geobotanical approach to detect land-use change of a Mediterranean landscape: a case study in Central-Western Sicily
2018
A landscape is a palimpsest of the interactions between human activities and ecological dynamics. In an interdisciplinary perspective of dialogue between the ‘Two Cultures’ (Natural Sciences and Humanities), a study of a rural area has been carried out through a reading of plant ecosystems as signs of human impact. The purpose of this paper—as part of the project ‘Harvesting Memories’: Ecology and landscape archaeology of Castro/Giardinallo Valley and Mt. Barrau district (Corleone, Palermo, Sicily)—is to analyse the formative-processes of a Sicilian rural landscape and its changes in the last century. A key element in the reconstruction of the formation of the present landscape is the serie…
Ancient human genomes suggest three ancestral populations for present-day Europeans
2014
We sequenced the genomes of a ∼7,000-year-old farmer from Germany and eight ∼8,000-year-old hunter-gatherers from Luxembourg and Sweden. We analysed these and other ancient genomes1,2,3,4 with 2,345 contemporary humans to show that most present-day Europeans derive from at least three highly differentiated populations: west European hunter-gatherers, who contributed ancestry to all Europeans but not to Near Easterners; ancient north Eurasians related to Upper Palaeolithic Siberians3, who contributed to both Europeans and Near Easterners; and early European farmers, who were mainly of Near Eastern origin but also harboured west European hunter-gatherer related ancestry. We model these popula…
La dimensione tecnologica del museo: forme, tecniche, "identità mutanti" tra storia e contemporaneità
2005
Nella cultura contemporanea il tema della conservazione dell’eredità storica, della rappresentazione e della trasmissibilità dell’arte è argomento ampiamente dibattuto. La forza culturale del museo, detentore dell’eredità, può essere interpretata secondo diverse traiettorie di forme. La memoria intende esprimersi sulle origini e sul significato della "macchina museale" attraverso l’analisi critica dell’oggetto, sia esso contenitore, palco di rappresentazione o scena interattiva. Sonda i processi di comunicazione relativamente alla forma architettonica, alla funzione ed alla fruizione del prodotto espositivo. Tenendo conto delle diverse scuole di pensiero sulla spettacolarizzazione dell’arte…
Expected number of massive galaxy relics in the present-day Universe
2013
The number of present-day massive galaxies that has survived untouched since their formation at high-z is an important observational constraint to the hierarchical galaxy formation models. Using three different semianalytical models based on the Millenium simulation, we quantify the expected fraction and number densities of the massive galaxies form at z>2 which have evolved in stellar mass less than 10% and 30%. We find that only a small fraction of the massive galaxies already form at z~2 have remained almost unaltered since their formation (<2% with Delta_M*/M*<0.1 and <8% with Delta_M*/M*<0.3). These fractions correspond to the following number densities of massive relics…
Modeling evolution of the San Andreas Fault system in northern and central California
2012
[1] We present a three-dimensional finite element thermomechanical model idealizing the complex deformation processes associated with evolution of the San Andreas Fault system (SAFS) in northern and central California over the past 20 Myr. More specifically, we investigate the mechanisms responsible for the eastward (landward) migrationof the San Andreas plate boundary over time, a process thathas largely determined the evolution and present structure of SAFS. Two possible mechanisms had been previously suggested. One mechanism suggests that the Pacific plate first cools and captures uprising mantle in the slab window, subsequently causing accretion of the continental crustal blocks. An alt…