CONTRIBUTIONS OF TUNNEL EROSION TO SEDIMENT YIELD IN A SEMI-ARID BASIN IN THE LOESS PLATEAU OF CHINA     

T.X. ZHU  Q.G. CAI  S.H.LUK Dr.  Department of Geography  University of Minnesota-Duluth  Duluth  MN  USA. Tel: --. Fax: --. Email: tzhu@d.umn.edu Researcher  Institute of Geography  Chinese Academy of Sciences  Beijing   《国际泥沙研究》2000,(4)

1 INTRODUCTIONSubsurface erosion has been increasingly recognized as a significant hillslope geomorphologic process(Carson and ~y, 1972; McCaig, 1983;, Harvey, 1982;Bryan and Harvey, 1985; Crouch andMcGarrity, 1986; Walsh and Howeds, 1988). However, most of the studies were conducted in hubedareas, especially in Britain (e.g. Gilman and Newson, 1980; Jones, 1981; Wilson and Small, 1984; Jones,1987; Jones et al, 1997). Jones and Crane (1984) found that soil piping contributes about …  相似文献   

History of the reindeer (Rangifer tarandus) in the eastern Baltic region and its implications for the origin and immigration routes of the recent northern European wild reindeer populations     

PIRKKO UKKONEN  LEMBI LÕUGAS  ILGA ZAGORSKA  LIGITA LUK&#;EVICA  ERVINS LUK&#;EVICS  LINAS DAUGNORA  HÖGNE JUNGNER 《Boreas: An International Journal of Quaternary Research》2006,35(2):222-230

A total of 45 subfossil reindeer (Rangifer tarandus) antlers and bones - artefacts excluded - have been found over the years in the Baltic countries of Estonia, Latvia and Lithuania. The relatively high number of specimens suggests a stable residence of the species in the eastern Baltic region. For the first time, 12 of these finds were radiocarbon-dated. The ages of the samples range between 12 085 and 9970 ¹⁴C yr BP (14 180-11 280 cal. yr BP), and cover the Lateglacial and early Holocene, a time period during which climatic conditions shifted from periglacial to temperate. The dates suggest a rapid colonization of the area during the deglaciation period and a local extinction around the Pleistocene-Holocene boundary. The results of the study do not support the theory that the recent wild reindeer populations of northern Europe had their origin in the Late Weichselian reindeer populations of the eastern Baltic region.  相似文献