Late Holocene debris cone development and vegetation and land-use history in the Pasture Beck valley, Lake District, NW England
Late Holocene debris cone development and vegetation and land-use history in the Pasture Beck valley, Lake District, NW England
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英格兰西北部湖区牧场贝克谷的全新世晚期碎片锥发育以及植被和土地利用历史
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
P. Wilson
中科院分区：
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作者：
R. Clark;A. Parker;D. E. Anderson;P. Wilson
对东湖区牧场贝克谷地一个小型碎屑锥远端边缘的沉积层序进行了调查，获得了有关锥体沉积阶段的时间和性质以及当地植被和土地利用历史的详细信息。两个埋藏的泥炭层的放射性碳测年表明，从公元8世纪末到13世纪初(1165-736卡)，圆锥体表面总体上是稳定的。BP)。堆积砾石沉积的间歇期中断了泥炭的堆积，可能是单一的短暂事件的结果。砾石为主的床代表了无粘性泥石流重新塑造的落石碎屑和冰川漂流的沉积，而细粒床可能是泥石流沉积的细粉冲刷形成的席状流的结果。地层证据表明，成矿沉积是快速连续堆积的。泥炭样品的花粉和木炭数据显示，在泥炭埋藏之前，成矿沉积物强化了土地利用。有人提出，景观不稳定首先与北欧-爱尔兰人定居和林地开垦有关，后来可能与公元13世纪高地牧场的扩张和更密集的放牧有关。当牧场贝克的数据与来自不列颠群岛其他地方的信息一起考虑时，很明显，并非所有全新世晚期高地地区的景观变化模式都可以归因于单一的原因。
Investigations of a sedimentary sequence exposed in the distal margin of a small debris cone in the valley of Pasture Beck, eastern Lake District, have yielded detailed information concerning the time and nature of cone aggradation phases and the local vegetation and land-use history. Radiocarbon dates from two buried peat beds indicate that the cone surface was generally stable from the late 8th to the early 13th centuries AD (1165–736 cal. BP). An interlude of colluvial gravel deposition interrupted peat accumulation and was probably the result of a single short-lived event. Gravel-dominated beds represent deposition of reworked rockfall debris and glacial drift by cohesionless debris flows, whereas finer-grain beds are probably the result of sheet-flows derived by washout of fines from debris-flow deposits. The stratigraphic evidence indicates that the minerogenic sediments accumulated in quick succession. Pollen and charcoal data from peat samples reveal intensification of land-use before burial of the peats by minerogenic sediments. It is proposed that landscape instability was associated first with Norse-Irish settlement and woodland clearance, and later, probably, to the expansion of upland pastures and more intensive grazing in the 13th century AD. When the Pasture Beck data is considered along with information from elsewhere in the British Isles, it is apparent that not all patterns of Late Holocene landscape change in upland areas can be ascribed to a single cause.