If you climb Jockey’s Ridge on North Carolina’s Outer Banks, you will come to a perspective where your eyes are just below, even with, and just above the dune’s crest. On a windy day, you will see a low haze moving rapidly just inches over the dune; it’s not fog. As you walk into the haze, you will both see and feel the composition of the haze: “Bouncing” grains of sand picked up and dropped in a repetitive process. The grains will sting as they impinge upon your skin. Lifted by the wind, the sand grains undergo the “bouncing” phenomenon known as saltation. It is by saltation that the wind created and now moves the dune, the largest such structure east of the Mississippi River.
Saltation can occur in any environment with an unconsolidated surface. Sand, pebbles and cobbles in a streambed undergo the process during turbulent flow. The greater the energy, the bigger the “bounce” and the larger the particle that does the bouncing with the current.
Now established, Jockey’s Ridge changes slightly with each wind, but it remains largely in place because the wind blows sometimes seaward and at other times landward. There’s little net change to the overall dune, at least not in the eyes of the casual observer, one, for example, who might climb to the dune’s top to learn how to hang glide during a vacation. Movement is more easily noticeable in smaller dunes than on a well-established mass that covers more than 400 acres and that rises about 100 feet above sea level. Jockey’s Ridge appears to be nearly 7,000 years old.
That’s a long time for something that is unconsolidated to remain in one place. Empires, religions, and political philosophies have risen and fallen during those millennia, all carried off by the current of moving humanity. The dune, with nothing cohesive to bind its constituent quartz and other mineral grains together, has endured. The winds of saltation moving it without moving IT: Seaward and landward, pendulum-like, the mass of sand is today what it has been through the rise and fall of the Egyptian, Persian, Alexandrian, Roman, Incan, Ming, Holy Roman, and Ottoman empires. They’re all gone; yet, they were supposedly during their time—at least in the minds of their constituents—consolidated.
It might be worth our efforts to take a mental walk up an imaginary Jockey’s Ridge to wonder a moment or two about those grains bouncing in the wind, first seaward and then landward, and then repeating the process. Opposite directions for those grains moved by something as invisible as the wind. And at the top, as we feel the sting of bouncing grains, we can ask ourselves about the underlying mass of humanity whose surface bounces in whatever direction the wind blows.
Saltation can occur in any environment with an unconsolidated surface. Sand, pebbles and cobbles in a streambed undergo the process during turbulent flow. The greater the energy, the bigger the “bounce” and the larger the particle that does the bouncing with the current.
Now established, Jockey’s Ridge changes slightly with each wind, but it remains largely in place because the wind blows sometimes seaward and at other times landward. There’s little net change to the overall dune, at least not in the eyes of the casual observer, one, for example, who might climb to the dune’s top to learn how to hang glide during a vacation. Movement is more easily noticeable in smaller dunes than on a well-established mass that covers more than 400 acres and that rises about 100 feet above sea level. Jockey’s Ridge appears to be nearly 7,000 years old.
That’s a long time for something that is unconsolidated to remain in one place. Empires, religions, and political philosophies have risen and fallen during those millennia, all carried off by the current of moving humanity. The dune, with nothing cohesive to bind its constituent quartz and other mineral grains together, has endured. The winds of saltation moving it without moving IT: Seaward and landward, pendulum-like, the mass of sand is today what it has been through the rise and fall of the Egyptian, Persian, Alexandrian, Roman, Incan, Ming, Holy Roman, and Ottoman empires. They’re all gone; yet, they were supposedly during their time—at least in the minds of their constituents—consolidated.
It might be worth our efforts to take a mental walk up an imaginary Jockey’s Ridge to wonder a moment or two about those grains bouncing in the wind, first seaward and then landward, and then repeating the process. Opposite directions for those grains moved by something as invisible as the wind. And at the top, as we feel the sting of bouncing grains, we can ask ourselves about the underlying mass of humanity whose surface bounces in whatever direction the wind blows.
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