Boulder Ridges on the Aran Islands (Ireland): Recent Movements Caused by Storm Waves, Not Tsunamis
Boulder Ridges on the Aran Islands (Ireland): Recent Movements Caused by Storm Waves, Not Tsunamis
复制标题
阿兰群岛（爱尔兰）的博尔德山脊：最近的运动是由风暴波而非海啸引起的
DOI：
--
复制
发表时间：
2012
期刊：
影响因子：
--
通讯作者：
M. Cook
中科院分区：
文献类型：
--
作者：
Rónadh Cox;D. Zentner;Brian J. Kirchner;M. Cook
爱尔兰的阿兰群岛是一个很好的地方来测试沿海巨石沉积物-包括在海平面附近重达几十吨的单个岩石和在海平面以上几十米处运输的重达几吨的碎屑-是否需要海啸才能就位，或者风暴波是否可以完成这项工作。沿着阿兰群岛的大西洋海岸，沿着排列着细长的鹅卵石、巨砾和巨砾堆积物。近几个世纪以来，没有海啸影响过这个地区，所以如果这些沉积物在现在形成或迁移，它们一定是被风暴激活的。我们发现了各种各样的证据，最近的山脊活动。首先，Hiatella arctica（潮下带钻岩双壳类，保存在山脊巨石中的生命位置）的贝壳产生的放射性碳年龄从公元200年到现代（公元1950年后）。其次，最近的运动是由目击者的帐户，钉几个单独的40-80吨块的运动到一个特定的1991年风暴和重复摄影在过去几个领域的季节（2006-2011年），捕捉移动的巨石（质量高达10.5吨），即使在没有特别大的风暴的年份。最后，地理信息系统将19世纪的地形测量图与21世纪的正射影像图进行了比较，结果表明，自19世纪中期以来，在一些地区，巨石山脊已经向内陆推进了数十米，超过了旧的田野墙壁。这些前进中的海脊含有在高水位线以上11米处质量高达78吨的巨砾，因此，自1839年调查以来，一定发生了足以搬运这些巨砾的波浪能量。因此，自1839年制图以来，有大量的证据表明海脊活动，而且在这段时间内，大西洋东北部没有海啸，我们得出结论，阿兰群岛的巨石海脊是由风暴波建造和移动的。
Ireland’s Aran Islands are an excellent place to test whether coastal boulder deposits—including individual rocks weighing several tens of tonnes near sea level and clasts weighing several tonnes transported at tens of meters above sea level—require a tsunami for emplacement or whether storm waves can do this work. Elongate deposits of cobbles, boulders, and megagravel are strung along the Atlantic coasts of the Aran Islands. No tsunamis have affected this region in recent centuries, so if these deposits are forming or migrating at the present time, they must be storm activated. We find a diverse range of evidence for recent ridge activity. First, shells of Hiatella arctica (subtidal rock-boring bivalves preserved in life position within ridge boulders) yield radiocarbon ages from ≈200 AD to modern (post-1950 AD). Second, recent motion is attested to by eyewitness accounts that pin the movement of several individual 40–80-t blocks to a specific 1991 storm and by repeat photography over the last few field seasons (2006–2011) that captures the movement of boulders (masses up to ≈10.5 t) even in years without exceptionally large storms. Finally, geographic information system comparison of nineteenth-century Ordnance Survey maps with twenty-first-century orthophotos shows that in several areas the boulder ridges have advanced tens of meters inland since the mid-nineteenth century, overrunning old field walls. These advancing ridges contain boulders with masses up to 78 t at 11 m above high-water mark, so wave energies sufficient to transport those blocks must have occurred since the 1839 survey. Thus, there is abundant evidence for ridge activity since the 1839 mapping, and as there have been no tsunamis in the northeastern Atlantic during that time period, we conclude that the Aran Islands boulder ridges are built and moved by storm waves.
孔隙率在区分海啸和飓风巨石就位中的作用——加勒比南部小安的列斯群岛的案例研究
影响因子：
5.3
作者：
Spiske M;Böröcz;Bahlburg
通讯作者：
Bahlburg