926 resultados para History in Ceará


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Analyses of pollen, macrofossils and microscopic charcoal in the sediment of a small sub-alpine lake (Karakol, Kyrgyzstan) provide new data to reconstruct the vegetation history of the Kungey Alatau spruce forest during the late-Holocene, i.e. the past 4,000 years. The pollen data suggest that Picea schrenkiana F. and M. was the dominant tree in this region from the beginning of the record. The pollen record of pronounced die-backs of the forests, along with lithostratigraphical evidence, points to possible climatic cooling (and/or drying) around 3,800 cal year B.P., and between 3,350 and 2,520 cal year B.P., with a culmination at 2,800-2,600 cal B.P., although stable climatic conditions are reported for this region for the past 3,000-4,000 years in previous studies. From 2,500 to 190 cal year B.P. high pollen values of P. schrenkiana suggest rather closed and dense forests under the environmental conditions of that time. A marked decline in spruce forests occurred with the onset of modern human activities in the region from 190 cal year B.P. These results show that the present forests are anthropogenically reduced and represent only about half of their potential natural extent. As P. schrenkiana is a species endemic to the western Tien Shan, it is most likely that its refugium was confined to this region. However, our palaeoecological record is too recent to address this hypothesis thoroughly.

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Der erste Universitätskurs in Norwegen, der komplett via Internet unterrichtet wird, wird in Kunstgeschichte angeboten. Dieses Projekt wurde im März 2000 mit einem Einführungskurs in die Kunstgeschichte gestartet. Aufgrund seiner modularen Struktur, visuell ansprechender Präsentationen, fachbezogener Ansätze sowie Möglichkeiten eines zweiseitigen Kommunikationsaustausches, kann das Interesse und der Einbezug der Studenten während der zweijährigen Dauer des Kurses aufrecht erhalten werden.

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History and Identity in the Late Antique Near East gathers together the work of distinguished historians and early career scholars with a broad range of expertise to investigate the significance of newly emerged, or recently resurrected, ethnic identities on the borders of the eastern Mediterranean world. It focuses on the "long late antiquity" from the eve of the Arab conquest of the Roman East to the formation of the Abbasid caliphate. The first half of the book offers papers on the Christian Orient on the cusp of the Islamic invasions. These papers discuss how Christians negotiated the end of Roman power, whether in the selective use of the patristic past to create confessional divisions or the emphasis of the shared philosophical legacy of the Greco-Roman world. The second half of the book considers Muslim attempts to negotiate the pasts of the conquered lands of the Near East, where the Christian histories of Hira or Egypt were used to create distinctive regional identities for Arab settlers. Like the first half, this section investigates the redeployment of a shared history, this time the historical imagination of the Qu'ran and the era of the first caliphs. All the papers in the volume bring together studies of the invention of the past across traditional divides between disciplines, placing the re-assessment of the past as a central feature of the long late antiquity. As a whole, History and Identity in the Late Antique Near East represents a distinctive contribution to recent writing on late antiquity, due to its cultural breadth, its interdisciplinary focus, and its novel definition of late antiquity itself.

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Vegetation changes in the Maya Lowlands during the Holocene are a result of changing climate conditions, solely anthropogenic activities, or interactions of both factors. As a consequence, it is difficult to assess how tropical ecosystems will cope with projected changes in precipitation and land-use intensification over the next decades. We investigated the role offire during the Holocene by combining macroscopic charcoal and the molecular fire proxies levoglucosan, mannosan and galactosan. Combining these two different fire proxies allows a more robust understanding of the complex history of fire re- gimes at different spatial scales during the Holocene. In order to infer changes in past biomass burning, we analysed a lake sediment core from Lake Peten Itza, Guatemala, and compared our results with millennial-scale vegetation and climate change available in the area. We detected three periods of high fire activity during the Holocene: 9500 e 6000 cal yr BP, 3700 cal yr BP and 2700 cal yr BP. We attribute the first maximum mostly to climate conditions and the last maximum to human activities. The rapid change between burned vegetation types at the 3700 cal yr BP fire maximum may result from human activity.

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The study of mass movements in lake sediments provides insights into past natural hazards at historic and prehistoric timescales. Sediments from the deep basin of Lake Geneva reveal a succession of six large-scale (volumes of 22 × 106 to 250 × 106 m3) mass-transport deposits, associated with five mass-movement events within 2600 years (4000 cal bp to 563 ad). The mass-transport deposits result from: (i) lateral slope failures (mass-transport deposit B at 3895 ± 225 cal bp and mass-transport deposits A and C at 3683 ± 128 cal bp); and (ii) Rhône delta collapses (mass-transport deposits D to G dated at 2650 ± 150 cal bp, 2185 ± 85 cal bp, 1920 ± 120 cal bp and 563 ad, respectively). Mass-transport deposits A and C were most probably triggered by an earthquake, whereas the Rhône delta collapses were likely to be due to sediment overload with a rockfall as the external trigger (mass-transport deposit G, the Tauredunum event in 563 ad known from historical records), an earthquake (mass-transport deposit E) or unknown external triggers (mass-transport deposits D and F). Independent of their origin and trigger mechanisms, numerical simulations show that all of these recorded mass-transport deposits are large enough to have generated at least metre-scale tsunamis during mass movement initiation. Since the Tauredunum event in 563 ad, two small-scale (volumes of 1 to 2 × 106 m3) mass-transport deposits (H and I) are present in the seismic record, both of which are associated with small lateral slope failures. Mass-transport deposits H and I might be related to earthquakes in Lausanne/Geneva (possibly) 1322 ad and Aigle 1584 ad, respectively. The sedimentary record of the deep basin of Lake Geneva, in combination with the historical record, show that during the past 3695 years, at least six tsunamis were generated by mass movements, indicating that the tsunami hazard in the Lake Geneva region should not be neglected, although such events are not frequent with a recurrence time of 0·0016 yr−1.