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Luis Gómez‐Orellana Pablo Ramil‐Rego Ernestina Badal Yolanda Carrión Marco Castor Muñoz Sobrino 《Boreas: An International Journal of Quaternary Research》2014,43(4):792-806
This paper presents the results of pollen and charcoal analyses carried out in the sedimentary formation of Ponta da Passadeira, south of the Tejo River estuary, Portugal. The data provide information regarding the evolution of the coastline and ecosystem of the estuary during the mid and late Holocene. The study focuses on a group of upright woody fossilized tree remains that, together with those identified earlier by García‐Amorena et al. (2007), form part of the fossil forest of Ponta da Passadeira. Eight remains were identified as Pinus pinaster, four as Pinus pinea and one as Pinus sp. Two specimens of these species were dated to 6523 and 5805 cal. a BP. Pollen analysis was undertaken in a clay layer located at the same point as the fossil forest, which is currently below sea level; the base of the clay layer was dated to 4906 cal. a BP. The pollen spectra reflect the dynamics of the vegetation that grew on this deposit, whereas the sporopollinic input masks the contribution of the regional vegetation. Wood charcoal remains recovered at an adjacent Final Neolithic settlement were also analysed, and a Pinus sp. specimen was radiocarbon dated to 5050 cal. a BP. The correlation amongst the three records provides key ecological markers for the understanding of the evolution of coastline ecosystems, and helps to clarify and understand the Holocene sea rise on the Atlantic seaboard of Iberia. The geographical location of Ponta da Passadeira is strategic because it enables a more clear definition of the configuration of landscapes that show an inflection point in this area of central Portugal. 相似文献
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This paper explores the activities and problems of indigenous women's organisations in Ghana. The survey data that form the basis of the analysis were collected in 1998 from a sample of 66 women's organisations in the districts of Atebubu and Techiman of Brong Ahafo Region in Ghana. The results suggest that despite the debilitating impacts of patriarchy, poverty and illiteracy, the women in both districts have managed to use their grassroots organisations to improve the socioeconomic circumstances of their members in particular and their communities in general. Given the dearth of theoretical and empirical analyses on grassroots mobilisation of women in sub‐Saharan Africa, the results presented here are intended to stimulate further research and discussion on the subject. 相似文献
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Sergey Sedov Elizabeth Solleiro‐Rebolledo Jorge E. Gama‐Castro Ernestina Vallejo‐Gmez Arelia Gonzlez‐Velzquez 《第四纪科学杂志》2001,16(4):375-389
Buried palaeosols of central Mexico, not previously analysed from a palaeopedological standpoint, have helped to develop a reliable regional model of Late Quaternary climatic change. This paper focuses upon morphological and micromorphological properties, particle‐size distribution, and extractable Fe, Al and Si of seven palaeosols (named PT1–PT7) in the vicinity of the Nevado de Toluca volcano. The characteristics of Andic Cambisol PT1, similar to those of modern soils in semi‐arid environments, indicate a drier climate in the first half of the Holocene. Humic Andosols PT2–PT4 are analogous to modern volcanic soils of humid forest environments. They show evidence that a moist palaeoclimate prevailed during marine oxygen isotope stages (OIS) 2 and 3. Luvisols PT5 and PT6, which are assumed to have formed at the end of marine OIS 5 to marine OIS 4, also indicate humid conditions. We attribute the differences between Andosols PT2–PT4 and Luvisols PT5–PT7 to variations in the duration in the pedogenesis rather than to changes in palaeoclimate. Micromorphological features of Andosol to Luvisol transition confirm that these soils form an evolutionary sequence. Being for the most part consistent with lacustrine records, the palaeosol properties do not reflect the episodes of ‘drier climate’ during the Last Glacial Maximum, however, as shown by diatom and palynological data from lake sediments. Mesoclimate variations and/or incompleteness of ‘soil memory’, reflecting mostly periods of humid pedogenesis, probably provide the reason for this disagreement. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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