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The degradation of the Jobourg fault-scarp occurred by cryoclastic processes in a periglacial environment during a part of Quaternary time. An attempt of quantification indicates a bulk scarp erosion of about 39 m3 m?2, while the head accumulated at the bottom of the fault scarp only represents 4.6 m3 m?2. To cite this article: M. Font et al., C. R. Geoscience 334 (2002) 171–178.  相似文献   
2.
Two climate simulations of 150 years, performed with a coupled ocean/sea-ice/atmosphere model including stratospheric ozone, respectively with and without heterogeneous chemistry, simulate the tropospheric warming associated with an increase of the greenhouse effect of carbon dioxide and other trace gases since 1950 and their impact on sea–ice extent, as well as the stratospheric cooling and its impact on ozone concentration. The scenario with heterogeneous chemistry reproduces the formation of the ozone hole over the South Pole from the 1970s and its deepening until the present time, and shows that the ozone hole should progressively fill during the coming decades. To cite this article: J.-F. Royer et al., C. R. Geoscience 334 (2002) 147–154.  相似文献   
3.
The Messinian sediments of northeastern Tunisia were deposited under an active tectonic setting. They are organized in sequences indicating a transitional deposit from margin – littoral to lacustrine – continental facies. These series unconformably overlie the Serravallian–Tortonian silty clays packages, and are overlain by the transgressive Early Pliocene marl (Zanclean). The presence of evaporitic strata points out to the Messinian Salinity Crisis described in the peripheral basins of the western Mediterranean. The Messinian sedimentation was found to have been closely controlled by transtensive tectonics and differential subsidence at a large spatio-temporal scale. It is organized in sequences typical of a depositional environment controlled by eustatism, tectonic and maybe by climate changes. Despite the existence of some local specific sedimentological characteristics, our results corroborate previous findings that pointed out to the Messinian times as a singular period all around the Mediterranean Basin. Field and subsurface seismic profile data helped reconstructing either the sedimentary or tectonic unconformities existing between the studied Messinian series and older Neogene successions.  相似文献   
4.
This survey of the coastal dunes of northern France is based on stratigraphy, 14C dating, sedimentology and morphology applied for palaeoclimatic and palaeodynamic purpose. The dunes rest on a Flandrian prism sealed by Atlantic peats grown backward from a subboreal dune ridge. Two historical building phases are recorded: the late Roman dunes and the 13th century dunes. These events are separated by pedogenesis. Contribution of reworked fluvial sands also records the recent climatic degradation, with an increased storminess (Little Ice Age) associated with more efficient erosion (soil erosion and floods). The dunes of Picardy also record the Global Warming: their morphologies attest a shift from parabolic into longitudinal, by coupling storminess and sea-level rise. To cite this article: M. Meurisse et al., C. R. Geoscience 337 (2005).  相似文献   
5.
瑯琊山森林进展演替的结果,亦即其顶极植物群落,将是以青檀、榉树、化香、五角枫、铜钱树等为优势树种的森林类型.苏皖江淮地区的地带性植被为落叶阔叶林,在中国植被区划系统中应属于暖温带落叶阔叶林区.  相似文献   
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A sediment sequence (SP05, 12.5 m long) was taken from the deep zone of Lake Saint-Point (850 m a.s.l.). Sedimentological analyses highlight two main contrasted periods of sedimentation: the Last Glacial Maximum (LGM)/Late Glacial characterized by high silicates and quartz contents the Holocene dominated by the carbonated fraction. At the beginning of the Holocene (11 400 years cal. BP), silicates fraction flux abruptly decreased. The shift between the Late Glacial and the Holocene periods may be explained by forest development in the catchment. From 10 200 to 6800 years cal. BP, silicates and detrital carbonate fractions remained stable before they progressively increased steady till 5000 years cal. BP. Both increases cannot be totally attributed to an anthropic impact since pollen data indicate continuous anthropic activities only dated back from 3000 years cal. BP. They thus resulted from a dominant climatic control. From 5000 years cal. BP, silicates content still increased while detrital carbonates input became steady due to a change in pedogenetic processes affecting the catchment. During the last millennium, silicates and detrital carbonate decreased, probably due to pastureland development.  相似文献   
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