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MARGOT BÖSE 《Boreas: An International Journal of Quaternary Research》1990,19(3):217-226
Till stratigraphical investigations in Berlin have been evaluated using the gravel counting method (4–12.5 mm). The results are compared with studies of several authors from the coastal area north of Berlin (Rügen and Stoltera Cliff near Warnemünde); the gravel counting results from Stoltera Cliff (Cepek 1973) are re-evaluated by means of cluster analysis, and a new stratigraphical interpretation of the sequence in the cliff is given. These results, together with a discussion of correlation problems of Weichselian and especially Saalian tills south of the Baltic Sea, lead to the following hypothesis: it is proposed that the ice margin of each glaciation has been nourished by several ice flows coming from different directions, for the most part turning from north-northeast at onset to east-northeast in later phases. Consequently, differences of composition are found in tills of the same age. 相似文献
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The declaration of a state of emergency in the South African linefishery in 2000 has had a positive impact on a few overexploited endemic seabreams (Family Sparidae). However, the population of the reef-dwelling dageraad Chrysoblephus cristiceps has been unresponsive to progressively stricter management regulations. After decades of unsustainable fishing mortality the species is in a critical state. In this paper, a method based on standardised probability of capture is used to develop an index of relative abundance for rare species, such as dageraad, which is more robust to changes in output control regulations than conventional methods. The results show a severe decline in dageraad capture probability in the south-west region of South Africa, from 8% in 1985 to <0.1% in 2011. The east region experienced a more rapid decline, from 24% in 1999 to <0.1% in 2011. A spatial comparison of the distribution of historical and recent dageraad probability of capture along the South African coastline indicates a range contraction commonly associated with the collapse of a population. The once-widespread species is now largely limited to a few locations in the Eastern Cape province and dageraad is mostly absent across its former western distribution. Although the historical decline has commonly been attributed to commercial overexploitation, the recreational sector had an estimated 3–5 times greater impact on the dageraad population than the commercial sector in recent years. Given that previous management regulations have been unsuccessful in arresting the decline of dageraad populations, assertive management is necessary to ensure the species’ sustainability. Rehabilitation of dageraad stocks will require a further decrease in fishing mortality, in conjunction with maintaining an appropriate marine protected area (MPA) network. 相似文献
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Stephen E. Ragone 《Environmental Geology》1986,8(3):129-132
In fiscal year 1982, the U S Geological Survey began an interdisciplinary research thrust entitled Toxic Waste-Groundwater
Contamination Program The objective of the thrust was to provide earth sciences information necessary to evaluate and mitigate
existing groundwater contamination problems resulting from the planned or inadvertant disposal of wastes and from certain
land-use practices, and to improve future waste disposal and land-use practices The program supports process-oriented and
interdisciplinary field research, and regional groundwater quality studies This article provides an overview of the current
(Fiscal Year 1985) activities of the Toxic Waste Program 相似文献
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Modelling palaeoglaciers in mountainous terrain is challenging due to the need for detailed ice flow computations in relatively narrow and steep valleys, high-resolution climate estimations, knowledge of pre-ice topography, and proxy-based palaeoclimate forcing. The Parallel Ice Sheet Model (PISM), a numerical model that approximates glacier sliding and deformation to simulate large ice sheets such as Greenland and Antarctica, was recently adapted to alpine environments. In an attempt to reconstruct the climate conditions during the Last Glacial Maximum (LGM) on Mount Dedegöl in SW Turkey, we used PISM and explored palaeoglacier dynamics at high spatial resolution (100 m) in a relatively small domain (225 km2). Palaeoice-flow fields were modelled as a function of present temperature and precipitation. Nine different palaeoclimate simulations were run to reach the steady-state glacier extents and the modelled glacial areas were compared with the field-based and chronologically well-established ice extents. Although our results provide a non-unique solution, best-fit scenarios indicate that the LGM climate on Mount Dedegöl was between 9.2 and 10.6 °C colder than today, while precipitation levels were the same as today. More humid (20% wetter) or arid (20% drier) conditions than today bring the palaeotemperature estimates to 7.7–8.8 or 11.5–13.2 °C lower than present, respectively. 相似文献
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