The Shadow
A satellite’s camera discovered a black-crescent-shaped image in the Sahara Desert that is surrounded by lighter terrain near Tanzania’s Ngorongoro Conservation Area, not far from the Olduvia Gorge.
Upon driving to the area where the image had been discovered, investigators found that the image is formed by highly magnetized sand, a sand dune composed of volcanic ash with iron content that sticks together, preventing the wind from blowing the sand away.
Because the wind in the area predominately blows from east to west, the black sand dune has been shaped to resemble crescent shaped formations discovered on Mars.
There have been two black sand dunes discovered in the area of Tanzania near the Serengeti National Park, and both have iron content derived from volcanic ash, rendering both as magnetized sand dunes. A demonstrator can toss a handful of the black sand into the air, and rather than the sand grains separating and being divided by the wind, the magnetized sand will separate during the throw but retract and cling together upon returning to the dune.
To the Massai, a nomadic tribe, the black sand dunes that move about 50 feet per year are sacred. Their belief is that the gods of Ol Doinyo Lengai Mountain, the source of the magnetic sand that formed from bits of iron in volcanic ash, control the rain.
The lighter Sahara sand surrounding the black sand dunes is constantly being reshaped by the wind while the magnetic sand resists being blown away. The wind blowing from east to west is credited by scientists for giving each of the black sand dunes its crescent shape while gradually moving each one eastward.
The Massai, who own cows and rely on their milk and blood for sustenance, are known to sacrifice a goat near a black sand dune to appease the gods, believing that the offering will persuade the gods to bring rain during times of drought. For the Massai, it remains taboo to tread upon the black sand dunes.
The Enhanced Thematic Mapper on NASA’s USGS Landsat 7 satellite first recorded the first black image in 2001. While staying intact, the black sand dune has relocated itself with the help of the wind nearly a quarter of a mile to the east by traveling from where it was first discovered and mapped by NASA.
