For years, it was assumed that giant boulders were compiled on a flat peninsula in western Island due to tsunamis. These boulders weighed four times more than a school bus and sit on a field of shallow cliffs overlooking the Atlantic Ocean. However, a recent study debunked those assumptions and provided us with interesting, yet worrisome data regarding the potential strength of violent storms and the subsequent storm surge they create. Using historical records, oceanographic data, and field measurements, researchers were able to track the potential wave heights reached in case of a storm. Furthermore, lighthouse records and measurements from offshore buoys point towards a landscape that is commonly ravaged by large storm waves. Past data dating back to 1861, documented a storm that was able to send waves crashing over a 220 feet tall light house near the boulder site. Records from this storm show that the lighthouse was entirely flooded with all of the glass breaking. Researchers configured the potential weight of a cubic meter of such a wave, a metric ton or 2,200 pounds and plugged in this value as well as historical and oceanographic data into a computer model. The results showed that the waves were powerful enough to wash massive boulders that originate beneath the ocean’s surface hundreds of feet inland, exactly on the peninsula on which they are currently found. Furthermore, the calculations showed that the waves can even rip boulders from the surrounding cliffs and that with each successive storm these boulders could be moved further and further inland. (Hall)
It is important to note that while these specific boulders were found to come from extremely powerful storms, the same conclusion cannot be broadened to include borders found further in-feild in New Zealand. These boulders weigh 150 tons and therefore, were probably deposited there via a tsunami (Barbano, Gerardi & Pirrotta). However, more evidence exists than simply their extremely high mass. Between the boulders, researchers discovered pieces of sandstone and broken shells embedded, that come only from the ocean floor. Here we see the process of story telling and the science of geology merge. Geologists use this science in order to fill in the gaps of history and find an explanation for phenomenons that we see today. This is exactly what they did in comparing these two sites. By comparing the two sites, the team found that storm surges can sometimes be just as storng as tsunamis. In fact, their calculations showed that a 65 foot tall storm surge is capable of ripping the same-size boulder from a cliff as a 16-feet-tall tsunami (Barbano, Gerardi & Pirrotta). In western Ireland, such tall storm waves are particularly common, occurring approximately 30 times every year (Barbano, Gerardi & Pirrotta).
This article specifically highlights the danger of powerful storms, such as hurricanes. While the fact that tsunamis are dangerous is somewhat common knowledges, people often underestimate the power behind storms. However, due to global warming, it is predicted that such storms are going to increase both in number and intensity in the near future so understanding the power of coastal waves and storm surge on coastal communities is extremely important. In fact, after recent ex-hurricane Ophelia hit Ireland just this past October, it exemplified just how much Europe’s cities are currently unprepared to deal with such storms (Feed). Furthermore, based on a recent observed increase of surface water temperature, we can anticipate an increase in severe storms of predominantly tropical origin reaching western Europe as part of 21st-century global warming (Feed). Therefore, preparatory actions in Europe need to be undertaken immediately to prepare for the strong storms that are predicted.
Works Cited:
Barbano, M., Pirrotta, C., & Gerardi, F. (2010). Large boulders along the coast of Ireland: Storm or tsunami deposits? Marine Geology, 275(1-4), 140-154. doi:10.1016/j.margeo.2010.05.005
Cara Tabachnick Feed. (2017, October 25). As Ophelia Strikes Ireland, Europe Buckles up for Stronger Storms. Retrieved December 09, 2017, from https://www.citylab.com/environment/2017/10/ophelia-ireland-storms-climate/543018/
Hall, S. (2017, November 29). Storm Waves With the Power to Heave Massive Boulders Over Cliffs. Retrieved December 09, 2017, from https://www.nytimes.com/2017/11/29/science/boulders-storms-waves-tsunamis.html?rref=collection%2Fsectioncollection%2Fscience&action=click&contentCollection=science®ion=stream&module=stream_unit&version=latest&contentPlacement=32&pgtype=sectionfront