Ocean Waves Are Powerful Enough to Toss Enormous Boulders Onto Land, Study Finds

During the winter of 2013-2014, the UK and Ireland were buffeted by a number of unusually powerful storms, causing widespread floods, landslides, and coastal evacuations. But the impact of the storm season stretched far beyond its effect on urban areas, as a new study in Earth-Science Reviews details. As we spotted on Boing Boing, geoscientists from Williams College in Massachusetts found that the storms had an enormous influence on the remote, uninhabited coast of western Ireland—one that shows the sheer power of ocean waves in a whole new light.

The rugged terrain of Ireland’s western coast includes gigantic ocean boulders located just off a coastline protected by high, steep cliffs. These massive rocks can weigh hundreds of tons, but a strong-enough wave can dislodge them, hurling them out of the ocean entirely. In some cases, these boulders are now located more than 950 feet inland. Though previous research has hypothesized that it often takes tsunami-strength waves to move such heavy rocks onto land, this study finds that the severe storms of the 2013-2014 season were more than capable.

Studying boulder deposits in Ireland’s County Mayo and County Clare, the Williams College team recorded two massive boulders—one weighing around 680 tons and one weighing about 520 tons—moving significantly during that winter, shifting more than 11 and 13 feet, respectively. That may not sound like a significant distance at first glance, but for some perspective, consider that a blue whale weighs about 150 tons. The larger of these two boulders weighs more than four blue whales.

Smaller boulders (relatively speaking) traveled much farther. The biggest boulder movement they observed was more than 310 feet—for a boulder that weighed more than 44 tons.

These boulder deposits "represent the inland transfer of extraordinary wave energies," the researchers write. " record the highest energy coastal processes, they are key elements in trying to model and forecast interactions between waves and coasts." Those models are becoming more important as climate change increases the frequency and severity of storms.