标题

沙丘复合物沿着密歇根湖的东南海岸:地貌历史和当代的过程

文档类型

本章

出版日期

2013年

出版来源

GSA观鸟指南:洞察密歇根盆地:盐沉积,影响结构,最小的盆地基石,冰川地貌,沙丘复合体,和沿海虚张声势的稳定性

卷号

31日

第一页

57

最后一页

102年

出版商

美国地质学会

国际标准图书编号

9780813700311

文摘

这个领域指南探讨了地貌学、生态学、现代过程、沉积结构和地貌历史的大型淡水沙丘系统密歇根湖的东南海岸。最近的研究在不同方面的沙丘在每个站突出显示。从北到南,这些停止包括P.J. Hoffmaster马斯基根附近的国家公园,密歇根州吉利根湖和绿山沙滩荷兰西南部,密歇根州Saugatuck沙丘国家公园和Saugatuck港自然区域,Saugatuck附近,密歇根州沃伦沙丘国家公园和大仅仅州立公园Indiana-Michigan边境和本顿港之间,密歇根州和山秃的东部边缘的印第安纳州沙丘国家湖岸,印第安纳州。所有描述的复合物低栖息海侵沙丘迁移内陆复合物在前湖平原或湾口酒吧。从内陆湖泊,典型的沙丘复杂的在这一领域由初期foredunes、一个既定foredune脊,抛物线沙丘复杂,back-dune岭复杂。所有阶段的生态succession-beginning先锋群落由海滩草和结束与介子的森林主要由橡木、枫,beech-are世界杯英格兰队vs丹麦队足彩通常出现在大沙丘复合物。 Like coastal dunes everywhere, surface changes in Lake Michigan dunes are driven by spatial gradients in sand flux, which, in turn, are determined by a complex interaction among wind, vegetation patterns, and preexisting topography. The patterns of surface change are modified by seasonal effects, with the majority of sand transport being associated with strong storms in the autumn, winter, and early spring. Sand can be temporarily stored in niveolian deposits during the winter, leading to oversteepened slopes, which collapse during the spring thaw. A variety of sedimentary bed forms and structures can be viewed in dunes along the southeastern shore of Lake Michigan, including wind ripples, lag deposits, raindrop impressions, adhesion ripples, adhesion warts, eolian turrets, sand pedestals, surface patches of fine-grained dark sand, pinstripes, paleosols, cross-bedding, climbing ripple lamination, niveolian deposits, and avalanche lobes. Most of these features are best seen immediately after strong storms in the autumn and winter. Remnants of older dune surfaces are exposed in a few places in back-dune ridge complexes; however, the current dune complexes are largely a product of events that occurred during and after the rise in lake levels to the Nipissing peak (ca. 4.5 ka). Broad fields of relatively low dunes developed during the drop in lake levels following the Nipissing peak. Beginning with the rise to the Algoma high lake level (ca. 3.2 ka), the lakeward edges of these fields were episodically reworked, forming the large parabolic dune complexes. A period of widespread dune stability resulted in the development of the Holland Paleosol, a particularly well-developed paleosol with Spodosol characteristics. Widespread dune growth and migration resumed prior to European settlement of the area and continue today.

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