A recent science field trip to the eastern shore in Maryland and Delaware taught me so much about the formation and destruction of our beaches. I’ve grown up loving the beach, so it was fascinating to look at things I’ve seen a million times before but learn about them from a different perspective. Every natural element on a beach serves a purpose. From the waves, to the sand, sand dunes, and beach grass–each one plays an important role in the creation of beaches.
One of the first things I noticed at Assateague Island, a protected national seashore, was how much black sand was present. At first we all thought it was dirty sand or stained from organic material. But I learned that black sand should always be present on beaches– it is an accumulation of the darker minerals from the ocean. If you carve out a ditch in the sand on a natural beach you will see stratified layers. It was beautiful! And it isn’t something you often get to see on developed beaches that are “groomed” with machines. Black sand is important to certain organisms because it heats up faster than the lighter sand and warms their eggs as they bury them.
The first thing you typically see when approaching a beach is a row of sand dunes, often obstructing your view of the ocean. To be honest, I never gave much thought to sand dunes before. I’ve seen signs saying “keep off sand dunes” but they didn’t make sense to me. Dunes are just piles of sand with some grass growing out of them, right? Wrong. Without sand dunes, there are no beaches. They are the “spine” of the beach, anchoring them in place. If they were gone, the wind and waves would eventually wash right over the beach displacing the sand and eventually destroying what we consider beaches today.
Sand dunes are created by nature. As waves wash organic material, shells, grass, organisms etc., ashore, they begin to accumulate in what is called a “rack line.” This rack line starts to trap more sand, slowly growing it into a baby sand dune. Once the baby sand dune is formed it quickly expands, accumulates sand and allows the organic material to take root and form into beach grass.
It is a fascinating process, but sadly, most of these rack lines are destroyed by beach grooming, which is necessary to remove trash. But without these accumulations natural sand dunes cannot grow. To compensate, a lot of beaches have man made sand dunes with planted beachgrass. But since these did not form naturally from the ground up, they don’t last as long and need constant replenishment.
There was so much more I learned on my 13 hour field trip to different beaches, including how important barrier islands are but how quickly they are disappearing and the details of what construction near a beach really means for a beach’s survival– but I don’t want to bore you with facts and science.
The key takeaway for me is that our beaches are at risk of over-development. The irony is we love beaches for their beauty, but we are beginning to love them to death. With sand depletion, rising sea levels, jetties, groins, and destruction of natural dunes to put in hotels, condos, and attractions, we are subjecting our beaches to destruction. As we move forward into the next few decades, hopefully there will be a solution so that we can all enjoy our beautiful beaches, but also make sure future generations can enjoy them too. But for now, let’s just try to not walk on sand dunes! 🙂
I hope you enjoy a few more images I captured below from the trip. Nature is truly the greatest artist.