Does it ever sound like the sand is squeaking when you take a walk on Alabama beaches? There’s a very scientific explanation for why that happens.
Squeaking – or whistling – sand is heard when quartz sand is well-rounded and shaped in spheres, according to Scientific American magazine.
“The frequency of the sound is related to the mean grain size and the amplitude is controlled by the surface texture of the grains,” according to the article. “The loudest squeaking observed by researchers was produced in the middle of the day by hot dry sand in the tidal zone, although they observed that completely water-saturated sand could be induced to squeak as water was receding.”
That fine, sugar-like sand on the Alabama coast has the right shape and make-up to squeak beneath your feet. When we walk over the sand, the particles rub over each other. The air between the grains of sand has to escape. The noise emits from the escaping air and the particles rubbing together.
And how does the quartz sand end up on our beaches? The pure white quartz crystal came from the Appalachian Mountains thousands of years ago and was deposited into the Gulf of Mexico. Wave motion and sea levels sort the sands to make them fairly uniform in grain-size. Those same waves, along with winds and storms, bring the sands to the shoreline in a process called “littoral drift.”
So next time you think you hear a squeaking or whistling sound when walking on the beach, you’re right. Those are perfectly tuned grains of sand singing to you.