GALVESTON.COM: Dunes: Galveston’s first line of defense
Barely a glance, visitors to the beach pass piles of sand en route to the waves, staring straight ahead, looking for a good place to settle down. But it’s not the water’s edge they’re looking for that’s the most important part of the shore. This distinction belongs to the seaside dunes on the upper beach, the part that protects everything behind it.
These protective batteries take time to form. The waves bring sand to the shore grain by grain. These squalls are picked up by offshore winds and blown across the beach close to the ground, in movements similar to ghostly apparitions. Grains of sand move until they land against an obstacle, any obstacle – a seashell, a piece of driftwood, a dead fish or an algae.
This is the strategy behind the human practice of placing hay bales, Christmas trees, and sand fences on the beach. Like the obstacles delivered naturally to the shore, each of them represents an obstacle to movement, where the sand settles and stays in place.
Over time, a pile of sand forms against an obstacle and continues to grow slowly. After months, the piles grow large and tall enough to provide fertile ground for the windblown seeds. The seeds settle, germinate and sprout, sending roots downward and long runners outward, slowly increasing their footprint in the sand. Their anchor roots and enlarged presence encourage more grains of sand to stop, thus increasing the pile, both taller and wider.
These piles become what Richard Davis called coppice mounds in his book The beaches of the Gulf Coast. They eventually come together to form dunes, those appropriately looking ridges that stretch along the upper shore.
Dunes are important, especially during hurricane season, as they provide an effective barrier against high water and storm surges. The Galveston Seawall also serves this purpose, but it is the seaside dunes that serve as Galveston’s first line of defense against the sea.
So, on your next beach trip, take a look around as you head for the waves. And maybe this time you’ll linger a little longer.