Skip to navigation | Skip to content

Desert dunes created by erosion not wind

Simpson sand dune

Linear dunes, such as those found in the in the Simpson-Strezelecki Desert, may have been formed by erosion.(Source: iStockphoto)


The findings published in the Geological Society of America Bulletin may help explain similarities between dunes found both on Earth and on Saturn's moon Titan.

Dune fields cover most of the Earth's deserts, including about 40 per cent of Australian deserts.

Linear sand dunes — long thin dunes that stretch across the landscape — are the most common type of desert dune.

The study by scientists led by Jianxun Zhou from the China University of Petroleum, looked at linear dunes in China's Qaidam Basin.

Jianxun and colleagues examined the dune's sediments and strata, concluding they were erosional in origin, created from local materials similar to wind-sculpted hills found in many deserts known as yardangs.

The researchers say the orientations of linear dunes are controlled by local geological features, rather than by prevailing wind direction.

"Our evidence from the Qaidam Basin evidently suggests that linear dunes can be of erosional origin and that the possibility of erosional origin should not be ruled out for the linear dunes in some other dune fields on Earth, such as the Simpson-Strezelecki Desert in Australia," they write.

They say their findings may explain why some linear dunes have very different internal structures and no distinct decline in age of sediments.

It may also provide a simple explanation why linear dunes don't migrate very far downwind even though they can be oblique to the direction that sand is transported; why they exist in modern deserts but can't be found in eolian sandstones formed from windblown sand; and why they can only be reproduced in the laboratory using wide bidirectional wind patterns.

To date different strata levels in the dunes, Jianxun and colleagues used a process called optically stimulated luminescence, which allowed them to determine the last time the sample sand gains were exposed to sunlight.

The researchers concluded that rather than previously speculated migration rates of three metres a year, the dunes were actually moving by as little as 0.02 to 0.04 metres annually.

Sand dune debate

Dune formation expert, Professor Robert Wasson from the National University of Singapore says the research revisits an old debate on the origins of desert dunes.

"Most dunes are formed by wind blowing sand around and accumulation of that sand," says Wasson.

"But there's been a long standing argument about whether or not some of these dunes can be formed by the erosion of adjacent bodies of sediment such as river or lake deposits, which then just pile up locally and don't migrate very far downwind at all."

Wasson has studied similar linear dunes in the Simpson-Strezelecki and Great Sandy Deserts of Australia.

"Some people think these long linear dunes migrate tens or even hundreds of kilometres, but all the evidence suggests they don't migrate very far at all," says Wasson.


According to Jianxun, the local findings could help explain the origin of similar dunes seen on the Saturnian moon Titan.

"No one has considered the possibility of an erosional origin for the linear dunes on Titan," says Jianxun


"If an erosional origin is considered, the morphodynamic interpretations of the linear dunes on Titan can also be greatly simplified," says Jianxun.

Tags: planets-and-asteroids, geology