Fossil hyrax dung and evidence of Late Pleistocene and Holocene vegetation types in the Namib Desert

Pollen was derived from fossil dung of herbivorous hyraxes, deposited in a rock shelter on the highest mountain in Namibia, Dâures or Brandberg, situated on the Namib Desert margin. Radiocarbon dating ranging in age between modern times and 30 000 yr BP showed it represents the first empirical pollen evidence of continental palaeovegetation during the Late Pleistocene along the western escarpment of southern Africa. The initial results indicate Last Glacial Maximum vegetation differed totally from the current pattern as vegetation types were dominated by small Asteraceae shrubs, in contrast to those of the Holocene and modern times which show more succulents, grass and woody elements (arboreal pollen). The results suggest that Cape floral communities did not reach into the tropics along the western escarpment of Africa, despite such pollen types occurring in marine cores. Copyright © 2004 John Wiley & Sons, Ltd.     

Magnetic carriers and remanence mechanisms in magnetite‐poor sediments of Pleistocene age,southern North Sea margin

Pleistocene sedimentary sequences in the East Anglian region of Britain record both major and minor climatic oscillations, and the impact of isostatic and eustatic variations. Intensively studied in terms of their lithology and biostratigraphy, the sequences have been difficult to place in an absolute timeframe. Dating and correlation by magnetostratigraphy has been attempted over a number of years. However, these sediments are difficult to date by palaeomagnetic means because they are poor in detrital magnetite, are subject to post‐depositional deformation and diagenesis, and have unknown rates of sedimentation. Determining whether their natural remanence magnetisation (NRM) directions are reliable thus requires information on the mode and timing of remanence acquisition. Here, we apply palaeomagnetic, rock magnetic and mineralogical analyses to identify the NRM carriers in these sediments and hence their palaeomagnetic reliability. Within oxidised fluvial sediments (the Kesgrave Formation), the magnetic carriers appear to be relict magnetic minerals (ferrian ilmenites, chromites, haematite and goethite), which sometimes carry a reliable primary depositional remanence (DRM) but often an overprinting viscous (time‐varying) remanence (VRM). Within some reduced marine and intertidal sediments (within the Crag basin), the iron sulphide, greigite, has been found to carry a reliable, ‘syn’‐depositional chemical remanence (CRM). In all the sediments, magnetic inclusions within silicates are abundant, are significant for the mineral magnetic signal but contribute little to any recoverable palaeomagnetic information. Copyright © 2005 John Wiley & Sons, Ltd.     

QUANTITATIVE MODELING OF SUSPENDED SEDIMENT IN MIDDLE CHANGJIANG RIVER FROM MODIS

1INTRODUCTIONThe quality of water is traditionally determined by col-lectingwatersamplesandanalyzingthesamplesin a lab-oratory. However, sampling is very much hard sledding,time-consuming, slow and expensive, and easily in thecontrol of weather conditions, and does not include allwater areas. Satellite estimates of water quality havefound widespread application. Remote sensing instru-ments have been applied in water quality monitoringwith varying success (DANA and RICHARD, 1999;RUDD…     

A middle surface concept (MSC) model for saturated sands in general stress space

An elastoplastic constitutive model is proposed for saturated sands in general stress space using the middle surface concept (MSC). In MSC, different features of stress–strain response of a material are divided into different pseudo‐yield surfaces. The true‐yield surface representing the true response is established by using various links between the yield surfaces. In this MSC sand model, several well‐known features of sand response are represented by three different pseudo‐yield surfaces, which are developed in a simple and straightforward way. These features include the critical state behaviour, the effects of state parameter, unloading and reloading plastic deformation, the influence of fabric anisotropy, and phase transformation line related behaviour. Finally, the model predictions and test results are compared for two different types of sands under a variety of loading conditions and good comparisons are obtained. The application of MSC to saturated sand modelling shows the versatility of MSC as a general concept for modelling stress–strain response of materials. Copyright © 2006 John Wiley & Sons, Ltd.     

陕西首次发现南方象化石

在陕西省澄城县采集到一对保存相当完好的南方象第三上臼齿化石。我国关于南方象化石的报导不多,在陕西省则是首次发现。这一发现对了解更新世时期南方象在我国的分布提供了新资料。     

Climatic deterioration and the end of the Gortian Interglacial in sediments from Derrynadivva and Burren Townland,near Castlebar,County Mayo,Ireland

Pollen and macrofossil analyses of two sequences of organic sediment in western Ireland have allowed the recognition of the latter parts of the Gortian Interglacial, a Middle Pleistocene temperate stage. The palaeobotanical information from the two sites identifies the preservation of partial sequences from the Gortian Interglacial (believed to be the equivalent of the Hoxnian Stage of Britain and the Holsteinian of Europe). The pollen and macrofossil data from one of the sites, Derrynadivva, span the middle and latter parts of the temperate stage. The results show that fire influenced the vegetation throughout the middle part of the temperate stage, and the termination of the organic depositional sequence appears to have been due to environmental deterioration. The former is identified through the abundant occurrence of charcoal in the sediments, whereas the latter is apparent in the sediment sequence and in the reworking of thermophilous pollen types into the upper part of the deposit. The second site, Burren Townland, records only part of the later zones of the interglacial, but the ericaceous assemblages of the latter part of the Gortian Interglacial are well developed and well preserved. Macrofossil analyses and scanning electron microscopy work on the pollen at the latter site has allowed the recognition of Rhododendron ponticum, adding to previous records of this species, which now has a very disjunct European distribution.     

达来诺尔的变迁

达来诺尔是在汗克拉源水头两个新生代断陷盆地、古地貌、新构造运动的影响下,几经变迁发育而成.中更新世中期该湖出现在好鲁厍一带,末期湖面扩大;晚更新世中期湖水占据现代分水岭两侧宽广地带,末期湖水越过分水岭超复全区;全新世地壳上升,湖水退缩在区内景低位置.     

记黄海、渤海海底发现的原始牛新亚种

本文记述的渤海,黄海海底发现的原始牛角心化石(3件),根据形态特征将其定名为Bos primigenius dalianensis subsp.nov.(原始牛大连亚种)。时代屆新生代第四纪晚更新世。这是我国首次于海底发现的原始牛化石。它的发现为探讨晚更新世时期黄海、渤海古地理环境,古气候条件,海水进退,冰期与间冰期的更替,哺乳动物的演化和迁徙提供了新的资料。     

Thresholds of geographic environmental elements in sediment yield of drainage basins

Threshold of environmental elements in drainage basin sediment yield refers to, under effect of climate, underlying surface and human activity, a turning point of abrupt changes in drainage sediment yield related to environmental element characteristics. Previous studies on threshold of sediment yield of relevant drainage basins were mainly concentrated on impact of natural zones with a few researches on impact of other environmental elements. Particularly studies on compound environmental element threshold in drainage basin sediment yield remain blank today. Studies indicate that sediment yield in drainage basins is affected by compound interactions and complex actions. Based on single element analysis, the present paper gives quantitatively compound threshold of environmental elements affecting sediment yield of the drainage basin between Hekouzhen and Tongguan in the middle Yellow River by the method of multi-variant, polynomial formula regression analysis.     

中天山坡地冰缘地貌的若干问题

由 1985—1989年野外调查结果和定位重复观测资料可知,本区坡地冰缘地貌的分布特征为:1.各类坡地冰缘形态彼此具有成因联系;2.不同序次的冰缘地貌类型具有各自的时空分异;3.不同的坡地冰缘地貌类型在一定条件下可有所转化。再则,本区风化以寒冻剥裂和寒冻楔入为主,呈现在时空和状态上为不可逆过程的耗散结构。