Modern and palaeo-shores from Pleistocene Marine Isotope Substage 5e (MIS 5e) featuring prominent cobble/boulder deposits from three locations, on the southern and eastern coast of Santa Maria Island in the Azores Archipelago, were compared, in order to test the idea of higher storminess during the Last Interglacial. A total of 175 basalt clasts from seven transects were measured manually in three dimensions perpendicular to one another. Boulders that exceeded the minimum definitional diameter of 25 cm contributed to 45% of the clasts, with the remainder falling into the category of large cobbles. These were sorted for variations in shape, size, and weight pertinent to the application of two mathematical formulas to estimate wave heights necessary for traction. Both equations were based on the “Nott-Approach”, one of them being sensitive to the longest axis, the other to the shortest axis. The preponderance of data derived from the Pleistocene deposits, which included an intertidal invertebrate fauna for accurate dating. The island’s east coast at Ponta do Cedro lacked a modern boulder beach due to steep rocky shores, whereas raised Pleistocene palaeo-shores along the same coast reflect surged from an average wave height of 5.6 m and 6.5 m. Direct comparison between modern and Pleistocene deposits at Ponta do Castelo to the southeast and Prainha on the island’s south shore produced contrasting results, with higher wave heights during MIS 5e at Ponta do Castelo and higher wave heights for the modern boulder beach at Prainha. Thus, our results did not yield a clear conclusion about higher storminess during the Last Interglacial compared to the present day. Historical meteorological records pit the seasonal activity of winter storms arriving from the WNW-NW against the scant record of hurricanes arriving from the ESE-SE. The disparity in the width of the marine shelf around Santa Maria Island with broad shelves to the north and narrow shelves to the south and east suggested that periodic winter storms had a more regular role in coastal erosion, whereas the rare episodic recurrence of hurricanes had a greater impact on southern and southeastern rocky shores, where the studied coastal boulder deposits were located.

中文翻译：

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来自圣玛丽亚岛（大西洋东北亚速尔群岛）的现代和更新世（MIS 5e）沿海巨石矿床的比较

比较了更新世海洋同位素5e（MIS 5e）的现代海岸和古海岸，这些海岸以亚速尔群岛圣玛丽亚岛南部和东部三个地点的卵石/巨石沉积为显着特征，以检验最后一次冰期之间的暴风雨更高。手动测量了七个样带中的总共175个玄武岩碎屑，它们彼此垂直。超过最小定义直径25厘米的巨石占碎屑的45％，其余碎屑属于大鹅卵石。根据应用两个数学公式估算牵引力所需的波高，对这些形状进行了分类，以求形状，尺寸和重量的变化。这两个方程都是基于“ Nott方法”的，其中一个对最长的轴敏感，另一个对最短的轴敏感。来自更新世沉积物的数据占主导地位，其中包括一个潮间带无脊椎动物动物，用于准确定年。由于陡峭的岩石海岸，该岛的东海岸塞多罗（Ponta do Cedro）缺少现代的巨石海滩，而同一海岸的凸起的更新世古海岸反映出平均波高分别为5.6 m和6.5 m。直接比较东南蓬塔多卡斯特洛和该岛南岸的Prainha的现代和更新世沉积物产生了相反的结果，在蓬塔多卡斯特洛的MIS 5e期间，波高更高，而在Prainha的现代巨石海滩，波高更高。从而，我们的结果并未得出关于末次冰期期间暴风雨与今天相比更高的明确结论。历史的气象记录将西非西北风到来的冬季风暴的季节性活动与西欧东南向来的飓风的鲜少记录相提并论。圣玛丽亚岛周围海架的宽度不均，北向有宽大的架子，南向和东向有狭窄的架子，这表明冬季的周期性风暴在海岸侵蚀中起着更规则的作用，而罕见的偶发性飓风反复发作对南部和东南多岩石的海岸产生了更大的影响，这是研究的沿海巨石矿床所在的地方。历史的气象记录将西非西北风到来的冬季风暴的季节性活动与西欧东南向来的飓风的鲜少记录相提并论。圣玛丽亚岛周围海架的宽度不均，北向有宽大的架子，南向和东向有狭窄的架子，这表明冬季的周期性风暴在海岸侵蚀中起着更规则的作用，而罕见的偶发性飓风反复发作对南部和东南多岩石的海岸产生了更大的影响，这是研究的沿海巨石矿床所在的地方。历史的气象记录将西非西北风到来的冬季风暴的季节性活动与西欧东南向来的飓风的鲜少记录相提并论。圣玛丽亚岛周围海架的宽度不均，北向有宽大的架子，南向和东向有狭窄的架子，这表明冬季的周期性风暴在海岸侵蚀中起着更规则的作用，而罕见的偶发性飓风反复发作对南部和东南多岩石的海岸产生了更大的影响，这是研究的沿海巨石矿床所在的地方。