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This paper provides the first systematic assessment of blanket mire degradation in the east Cheviot Hills, Northumberland. The extent of erosion is mapped over a 32 km2 area of peat. Erosion affects 37% of the blanket peat. Erosion forms consist of anastomosing (7%), linear (21%) and dendritic (9%) gully systems together with peat slides (<1%). Topography is the primary influence on gully system pattern. Spatial variations in gully form can be partly explained by position in the stream network (stream order) and local variations in the depth of peat. A sequential scheme of gully development is described. Gullies evolve initially through a phase of rapid downcutting to the peat base, followed by lateral erosion and gully widening becoming dominant through a process of roughly parallel wall retreat. As gully width increases re‐deposition of peat occurs and re‐vegetation occurs on the gully floor. Comparative photography reveals that gully patterns have been stable over the past 32 years and in some areas for over 70 years. It is possible that gully systems in places are in excess of 500 years old. 相似文献
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Oral historians have begun to use interviews in significantways to supplement what may be described as the more traditionalinstitutional "bricks and mortar" histories of colleges anduniversities. Many large public universities in the Americaswere founded after 1850 and first published their historiesat the half-century mark following the beginning of the twentiethcentury. In many instances, these college histories focusedon firsts and founders and gave particular attention to thephysical development of the campus and especially the constructionof buildings. These two books, one from the University of Floridain Gainesville, and the other from the University of Albertain Edmonton, Alberta, Canada, present an interesting contrastin the use of oral history in tracing the histories of thesetwo universities from 1906 to 2006. In the 相似文献
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Jeff T. Williams 《International Journal of Osteoarchaeology》1992,2(2):131-138
Several errors in the early literature discussing life-table analysis of skeletal populations are potentially misleading to the researcher unacquainted with the mathematical methods of palaeodemography. Additional errors document the hazards of borrowing life-table methods and equations from other applications without fully realizing their context, interpretation, and the potential restrictions on their use. A simple generalization of the life-table equations explicitly to reveal their dependence on the entry age and width of the age intervals used will facilitate the correct computation of life tables and readily accommodate the use of unconventional or otherwise non-standard cohorts. A general procedure for computing a life table for a skeletal population is presented, and a numerical example is included to illustrate the method. 相似文献
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