Singing Sand
Go to the Gobi Desert in Asia or Great Sand Dunes
National Park in Colorado, and you might just hear
a spooky tune. The massive beachy formations
make a low roar that has frightened and intrigued
intrepid travelers going back at least as far as the
13th century, when Marco Polo compared it to
“the sounds of all kinds of musical instruments.”
But there’s a likely explanation: The dunes prob-
ably start to sing as grains slide, avalanche-style,
off the slopes. A 2012 study—in which physicists
triggered the necessary cascade by scooting
downhill on their butts— hypothesized that the
phenomenon’s distinctive variations in pitch are
due to differences in grain size.The Vocal Memnon
Built nearly 3,500 years ago, the Colossi of
Memnon guard the tomb of Egyptian pharaoh
Amenhotep III near Luxor. But one sentinel was
not silent at his post: He “sang” at dawn. This
sparked a tourist craze, and visitors left an-
cient Yelp reviews in the form of graffiti. Julia
Balbilla, a Roman noble who visited in 130 A.D.,
wrote a poem on the statue’s leg comparing the
sound to “ringing bronze.” The music appar-
ently died around the time Roman Emperor
Septimus Severus ordered repairs to the sculpture
in 200 A.D. That could be a clue: Perhaps cracks in
the stone collected dew, creating sonic vibrations
as temperatures rose and warmed the liquid.55 POPSCI.COM • WINTER 2019WHAT WAS THAT?no.
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