Orange dunes stand out against dark sandstone in Algeria

Today’s Image of the Day from NASA Earth Observatory features the northern edge of Tassili n’Ajjer National Park in Algeria. In the photo, which was captured by an external camera mounted on the International Space Station, orange sand dunes contrast with dark sandstone.

“The park’s name translates to “plateau of chasms,” and these signature ravines wind through the rock in the right of the image. On the left, wisps of cloud overlie a dune field that has swept over the low-lying regions north of the Fadnoun Plateau,” reports NASA.

“Rising to elevations of over 1,500 meters (4,900 feet) on average, the current plateau has been shaped by thousands of years of water and wind erosion. Though the area is now hyper-arid, ancient rivers once cut narrow canyons almost 240 meters deep into the sandstone as they flowed north toward lakes that filled what are now large dune fields called ergs (“sand seas”). Issaouane Erg, shown above, contains some of the tallest star dunes on Earth.”

There are also large pillars of resistant sandstone that have persisted as strong winds eroded the surrounding rock. These large pillars are referred to as the “Forest of rock.” 

Humans have inhabited the town of Illizi, which stands at the northern edge of the plateau, since 10,000 BCE. This long history is recorded in rock engravings.

Image Credit: NASA Earth Observatory 

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By Chrissy Sexton, Earth.com Editor

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