Size and shape characteristics of drumlins, derived from a large sample, and associated scaling laws
Size and shape characteristics of drumlins, derived from a large sample, and associated scaling laws
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DOI：
10.1016/j.quascirev.2008.08.035
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发表时间：
2009-04-01
影响因子：
4
通讯作者：
Ng, Felix S. L.
中科院分区：
文献类型：
--
作者：
Clark, Chris D.;Hughes, Anna L. C.;Ng, Felix S. L.
流过沉积床的冰盖通常会产生一种沿冰流方向呈流线型的水泡状地貌景观，每个凸起的长度约为10（2）至10（3）米，起伏约为10（1）米。对它们的形成有一个令人满意的解释，从而对它们的冰川学意义有一个评价。仍然难以捉摸最近的一项进展是在陆地形成过程的数值模拟方面。在未来的建模工作的预期，本文的动机是强大的数据drumlin的大小和形状模型testing.From数字高程模型和卫星图像的英国和爱尔兰的drumlin映射系统的程序的要求，我们使用的地理信息系统编译长度L的一系列统计数据。宽度W和伸长率E（其中E = L/W）。发现平均L为629 m（n = 58，983），平均W为209 m，平均E为2.9（n = 37，043）。大多数鼓鱼的长度在250到1000米之间;宽度在120到300米之间;长度是宽度的1.7到4.1倍。对这些数据和鼓林宽度对长度的曲线图的分析揭示了一些新的见解。所有的频率分布是单峰的，我们推断，“鼓林”的地貌标签是公平的，因为这是一个真正的单一人口的地貌，而不是不同的地貌类型的混合物。Drumlin尺寸显示了约100 m（水平）的清晰最小边界。也许鼓林是在许多尺度上产生的，这是最小值，或者这个值可能是在它们生长和伸长之前凹凸产生（“原始鼓林”）的基本尺度的指示。找到了鼓林宽度和长度之间的关系（r（2）= 0.48），当以米为单位测量时，约为W = 7 L-1/2。在E-W-L空间中绘制的数据云的边界是一条令人惊讶的清晰定义的线，并记录了与尺度相关的最大伸长率极限（当L以米为单位时，近似为E-max = L-1/3）。对于一个给定的长度，由于某种原因，鼓形物不超过这个比例定律定义的伸长率。我们还报告并比较了我们的统计数据与来自约50项已公布调查的措施的合并样本（25，907个鼓）。任何理论都必须能够解释本文报道的Drumlin统计和基本标度特性，从而为Drumlin建模提供了强有力的测试。(C)2008爱思唯尔有限公司保留所有权利。
Ice sheets flowing across a sedimentary bed usually produce a landscape of blister-fike landforms streamlined in the direction of the ice flow and with each bump of the order of 10(2) to 10(3) m in length and 10(1) m in relief Such landforms, known as drumlins, have mystified investigators for over a hundred years. A satisfactory explanation for their formation, and thus an appreciation of their glaciological significance. has remained elusive. A recent advance has been in numerical modelling of the land-forming process. In anticipation of future modelling endeavours, this paper is motivated by the requirement for robust data on drumlin size and shape for model testing.From a systematic programme of drumlin mapping from digital elevation models and satellite images of Britain and Ireland, we used a geographic information system to compile a range of statistics on length L. width W, and elongation ratio E (where E = L/W) for a large sample. Mean L, is found to be 629 m (n = 58,983), mean W is 209 m and mean E is 2.9 (n = 37,043). Most drumlins are between 250 and 1000 metres in length; between 120 and 300 metres in width; and between 1.7 and 4.1 times as long as they are wide. Analysis of such data and plots of drumlin width against length reveals some new insights. All frequency distributions are unimodal from which we infer that the geomorphological label of 'drumlin' is fair in that this is a true single population of landforms, rather than an amalgam of different landform types. Drumlin size shows a clear minimum bound of around 100 m (horizontal). Maybe drumlins are generated at many scales and this is the minimum, or this value may be an indication of the fundamental scale of bump generation ('proto-drumlins') prior to them growing and elongating. A relationship between drumlin width and length is found (with r(2) = 0.48) and that is approximately W = 7 L-1/2 when measured in metres. A surprising and sharply-defined line bounds the data cloud plotted in E-W-L space, and records a scale-dependent maximum elongation limit (approximated by E-max = L-1/3, when L measured in metres). For a given length, for some reason as yet unknown, drumlins do not exceed the elongation ratio defined by this scaling law. We also report and compare our statistics to an amalgamated sample (25,907 drumlins) of measures derived from around 50 published investigations. Any theory must be able to explain the drumlin statistics and fundamental scaling properties reported herein and they thus provide powerful tests for drumlin modelling. (C) 2008 Elsevier Ltd. All rights reserved.