Search results for "Aridification"
showing 7 items of 17 documents
The phylogeny of the Papaveraceae sensu lato: morphological, geographical and ecological implications
1995
On the background of the phylogeny of the Papaveraceae s.l., the evolution of the androecium and gynoecium, the geographical distribution, and the ecological differentiation of the family is discussed. An effort is made to homologize the diverse androecia of Pteridophyllum, Hypecoum, Fumariaceae and Papaveraceae s.str., and it is concluded that both the polyandrous androecium as found in the Papaveraceae s.str. and the polycarpellate gynoecium as found in Papaveraceae s. str. subfam. Papaveroideae incl. Platystemonoideae are secondary and derived from whorled oligomerous androecia and bicarpellate gynoecia, respectively. The comparative consideration of the geographical distribution, ecolog…
Climate change and the collapse of the Akkadian empire: Evidence from the deep sea
2000
The Akkadian empire ruled Mesopotamia from the headwaters of the Tigris-Euphrates Rivers to the Persian Gulf during the late third millennium B.C. Archeological evidence has shown that this highly developed civilization collapsed abruptly near 4170 ± 150 calendar yr B.P., perhaps related to a shift to more arid conditions. Detailed paleoclimate records to test this assertion from Mesopotamia are rare, but changes in regional aridity are preserved in adjacent ocean basins. We document Holocene changes in regional aridity using mineralogic and geochemical analyses of a marine sediment core from the Gulf of Oman, which is directly downwind of Mesopotamian dust source areas and archeological si…
Early pastoral communities in the mountains of Sicily. Prehistoric evidence from Vallone Inferno (Scillato) in the palaeoenvironmental framework of t…
2021
Abstract This paper discusses the Middle Neolithic and the Early Bronze Age phases of the occupation of a rock shelter at Vallone Inferno (Scillato, Palermo) in Sicily. Vallone Inferno is a key site for studying the early establishment and development of pastoralism in the prehistoric mountainous environments of Sicily. Seasonal use of the site as a shelter is documented for the earliest pastoral communities that exploited the Madonie mountain range. The results of the analysis of pottery and lithic assemblages contribute to the definition of two chronocultural frameworks that were linked by the same economic subsistence base. The special role of obsidian emerges, while the mobility pattern…
New data on Sicilian prehistoric and historic evolution in a mountain context, Vallone Inferno (Scillato, Italy)
2013
Vallone Inferno rock-shelter is an archaeological site located in the Madonie mountain range in Sicily. Archaeological excavation and research have provided a long prehistoric and historic sequence from the Neolithic to the medieval period, this being the most complete work in this area at present. In this paper we present the preliminary data provided by a multidisciplinary study based on pottery, lithic, human, faunal and plant remains. Stratigraphic studies have identified four complexes, of which complex 3 has provided almost all the archaeological remains. 14C AMS dates, obtained from four samples, place the human activities between 2601 cal BC and 644 cal AD. These dates are coherent …
Holocene vegetation and fire dynamics in the supra-mediterranean belt of the Nebrodi Mountains (Sicily, Italy)
2012
High-resolution pollen, macrofossil and charcoal data, combined with accelerator mass spectrometry 14C dating and multivariate analysis, were used to reconstruct Holocene vegetation and fire dynamics at Urio Quattrocchi, a small lake in the supra-mediterranean belt in the Nebrodi Mountains of Sicily (Italy). The data suggest that after 10 000 cal a BP increasing moisture availability supported closed forests with deciduous (Quercus cerris, Fagus sylvatica and Fraxinus spp.) and evergreen (Quercus ilex) species. Species-rich closed forest persisted until 6850 cal a BP, when Neolithic activities caused a forest decline and affected plant diversity. Secondary forest with abundant Ilex aquifoli…
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…
A multidisciplinary approach to reveal the Sicily Climate and Environment over the last 20 000 years
2010
Abstract We present a thorough review of the knowledge on the climate and environment in Sicily over the last 20 000 years, taking into account results of several studies carried using terrestrial and marine records. We obtain a coherent framework of the most important changes succeeded in the island, even if some points need further investigation. All the reconstructions of surface temperatures of the seas and the air surrounding Sicily point out severe climatic conditions during the last glacial period. The steppe- and semisteppe-like vegetation pattern testifies, together with additional evidence from geochemical data of lacustrine evidence, markedly arid conditions. Fi-nally, significan…