While hiking on Bequia, I heard something unusual. If you listen carefully, you may discover that sand, at various beach locations “sings.”
Sand dunes here seem to have a built-in sound track. While “music” emanating from the Bequia dunes at times can be compared to the strains of a chorus, the effect at other times more closely resembles the playing of violins.
Reverberations oscillated into world headlines in 1969 when Apollo 12’s astronauts sent Intrepid‘s descent stage crashing into the sandy Ocean of Storms on the moon. Scientists are still trying to understand the bell-like reverberations that were recorded through a moon-based seismometer.
Sand dunes, whether on the Moon or on Bequia, would not seem to be a natural sound generator. The fact is, however, dunes in many parts of the world squeak, roar or boom.
For a thousand years, literature has mentioned singing sands. Venetian traveler Marco Polo frequently refers in his account The Travels of Marco Polo to musical sands and the superstitions attached to them.
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The ancient Chinese knew of the phenomenon as well. One Chinese writer left an account of an area in Kansu Province where noise-generating sand was noted in the 9th century. The document speaks of a “Hill of Sounding Sand” that was 500 feet high. According to the author, it possessed strange supernatural qualities: “The peaks taper up to a point, and between them there is a mysterious hole which the sand has not been able to cover up.”
The writer observed that in the summer, if men or horses trod upon the hill, sounds could be heard for great distances. The manuscript spoke of a custom that was used to induce singing sands: “It is customary during the Dragon Festival for people to clamber up to the highest points and rush down again in a body, which causes sand to give forth a rumbling noise.”
In the Western Hemisphere, Henry David Thoreau heard singing sands while walking on a New Hampshire beach. He noted the sound resembled that made by rubbing a finger over wet glass.
British naturalist Charles Darwin was the first scientist to examine the phenomenon. In his book A Naturalist’s Voyage Round the World, an entry for April 19 1832, reads: “Leaving Socego, we retraced our steps. It was very wearisome work, as the road ran across a hot, sandy plain. I observed that each time the horse put its foot on the sand, a chirping noise was produced.”
Some 300 years ago, a strange Middle Eastern legend arose, a legend Darwin had heard about. It concerned a monastery buried in sand for centuries, the bells of which gave off a drawn-out note. People passing by were awestruck as they came within earshot of the mysterious ringing dune. But the place where they heard it was deserted. The “Mountain of the Bell” in time passed into legend.
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Darwin decided to investigate. Visiting the locale, he asked a guide to climb up the sand mountain on the “musical side.” It was not until the guide had reached some distance, Darwin wrote, “that I perceived the sand to be in motion. In the beginning, the sound might be compared to that of a harp. As the increased velocity of the descent agitated the sand, the noise more nearly resembled that produced by drawing a moistened finger over glass.”
Other places where “singing sands” have been heard include the western coast of Wales, the island of Bornholm off the coast of Denmark, Bequia, and New South Wales, Australia.
What produces the sounds? The sound may involve films of gas, deposited upon the surface of grains during evaporation. Such films may act as elastic cushions separating the quartz grains. These cushions are capable of considerable vibration, which may be translated into sound, produced after any quick disturbance of sand.
The “singing” of sand may be the audible consequence of billions of minute crystals being rolled one against another by wind. Or, since “singing” is sometimes more pronounced after sundown, another theory could hold true. A mass of sand absorbs heat during the day and, with nightfall, as each sand particle contracts, a dune settles; in such movement, sounds may originate. On Bequia, singing sands have been heard on Princess Margaret Beach, Crescent Beach, Lower Bay Beach, and around Friendship Bay.
Spontaneous “music” arising from sand has long intrigued scientists and writers. The next time you’re hiking among Caribbean sand dunes, keep an ear open for one of the strangest concerts ever to come from nature. If you listen carefully, you may hear a hauntingly beautiful sound. Singing sands are a natural curiosity, a phenomenon in Mother Nature’s bag of tricks that astonishes all who hear them.
Joe Zentner is a freelance writer and a student of unusual environments. He has published articles in both scholarly journals and popular magazines.