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Geo-Joint: Sandy Beaches on the Move

Posted on June 20 2017

Does any bit of ground change its appearance on a seasonal, weekly, daily, or even hourly basis as much as the beach? The tide comes in and goes out a couple of times a day in most places, narrowing and widening the margin between land and sea. Different days produce greater or smaller piles of washed-up kelp, flotsam, and jetsam, and different seasons make for a blanket of soft sand, or a deflated, cobble-strewn apron at the ocean’s edge. It’s all very cyclical, constantly in motion, and influenced by so many factors that it is hard to pinpoint just what might be causing particularly intense swings in beach conditions.

The rocky cobble of Dooagh Beach awaits the return of its golden sands.

Beyond the uncountable biological variations that go on mostly unnoticed by beachgoers, it’s the more starkly visible state of the physical beach itself that commands our attention. We know we want to step off the pavement and push our toes into soft warm sand, wander to the perfect spot to throw down the towel, and get down to some serious relaxation. Ah, the warm sand—it so perfectly molds to our particular contours. That’s summertime, and quite unlike what you might find several months later when winter storms have stripped a lot of that sand away, sometimes down to either bedrock or perhaps a bank of smooth, rounded cobbles. It usually goes like this, from deep sand to lower, coarser material as larger, more energetic wave action drags sand offshore in winter, and smaller, gentler swells push it back toward land in spring and summer.

The people of Achill Island, Ireland were used to this kind of coming and going at Dooagh Beach, part of their front door to the Atlantic. It was the expected rhythm of the beach until 1984, when the sand departed amidst heavy winter storms, and didn’t come back. Achill’s formerly robust tourist trade diminished as the once-broad beach was reduced to a rocky shore, picturesque in its own way, but not a surface one could easily stroll upon. Over the course of the last 33 years, the locals grew to accept that their interface with the Atlantic would never be quite as inviting, or lucrative. But this spring, the ocean decided to return what it had snatched away. In the course of several days, the sand was carried back to Dooagh Beach, and not just a sparse, token layer. A full and very broad beach has reappeared, much to everyone’s delight. Oceanographers and geologists studying such movements know that if sands are moved far enough offshore they may take much longer than one season to reappear or may be hauled so deep that wave action never has the access to push them ashore again. Luckily for the denizens of Achill Island, deep tides and just the right swell action gave them back their beach. For now.

Dooagh Beach now resembles the wide sands of nearby Keel Beach, shown here.

Nature, then, taketh away but can in time restore the scene. Things get a little more permanent when humans interfere with the natural process. People find sand useful for many things beyond reclining upon. It is highly sought after as a construction material, fundamental to the making of concrete, and the beach is a great source of well-sorted, clean grains. Fortunately, beach communities in many parts of the world have recognized the value of maintaining a healthy beach environment, but even where laws exist to prevent beach sand mining, the practice goes on covertly. In 2008, there was a particularly egregious example of this at Coral Springs, Jamaica, when an entire beach was loaded up and hauled away. Police estimate that 500 truckloads of pristine white coral sand was stolen, most likely for the hotel construction trade. Sand is used for all kinds of smaller-scale building in Jamaica, but it is thought that with this much volume, it had to be linked to major operators. While the removal of so much sand portends extreme local ecological disruption, it also put a halt to plans to build a resort where that beach had been. The lack of a scenic Caribbean beach would severely limit the attractiveness of such a hotel. A very slow-moving investigation which has somehow turned up no suspects led many to surmise that the local authorities were involved in the crime. Replenishment of all that missing sand by natural processes will also be slow going. The continuous grinding up of dead coral pieces by wave action and parrotfish, plus the sediment from Jamaica’s short rivers will eventually rebuild the beach, but it will take a long time.

An intact Jamaican beach—the kind tourists want to relax on.

Beach sand has many practical values to humans and the rest of nature beyond looking good and generating tourist capital. It provides a protective barrier to coastline erosion and is of course its own unique biome for thousands of organisms. The ecology and politics of sandy beaches are too complex to delve into fully in one Geo-Joint. We’ll be revisiting the subject in the future to find out more about the processes and pressures upon the sandy strip that separates the sea from the shore. In the meantime, shut off your computer, push away from that desk….and go to the beach!


Think you’d like to go see the returned sands of Dooagh Beach? Check out this tourist wall map of Ireland by National Geographic, filled with notations on scenic and historic Irish locales you’ll want to include on your trip. Click here:




caption: The rocky cobble of Dooagh Beach awaits the return of its golden sands.
source: John Lucas (CC by SA 2.0)
caption: Dooagh Beach now resembles the wide sands of nearby Keel Beach, shown here.
source: Wikimedia Commons: Ire2500 (Public domain)
caption: An intact Jamaican beach—the kind tourists want to relax on.
source: Max Pixel: unknown (Public domain)

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