EarthWatch: California's Algodones Dune Field

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A variety of sand dunes make up the Algodones Dunes in southeastern California. 

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NASA Earth Observatory image created by Jesse Allen and Robert Simmon, using EO-1 ALI data provided courtesy of the NASA EO-1 team and the United States Geological Survey. 

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Satellite view of the earth. Title, Earth Watch, Exploring the Blue Planet by Satellite
 
Logo, Earth Observatory, earth observatory dot nasa dot gov, Advanced Land Imager, Earth Observing 1 satellite. A satellite view of beige and tan sand dunes. Text, February 24, 2011, California's Algodones Dunes. The Algodones Dunes in southeastern California feature four types of sand dunes.
 
Label, Simple Barchan Dunes on tan sand dunes with ripples. Text, Most are simple barchan dunes, the most common type in the world. Their crescent shapes are the result of winds blowing consistently in the same direction.
 
A plant label is added at the edge of the barchan dunes and a waterways label is added over flat areas with rivulets etched in the earth. Text, In addition to the winds, water flowing from the mountains in the east and the plants that grow in the waterways constantly reshape their forms.
 
While individual sand dunes change shape continuously, dune fields may persist for thousands of years.
 
A compound barchan dune label is added over a section of the dunes with smaller ripples. Text, The area's large, compound barchan dunes are the oldest, estimated to be 15,000 to 18,000 years old.
 
They are crescent-shaped and are superimposed by other smaller dunes with crests running diagonally from southwest to northeast.
 
Two new labels are added near the edge of the barchan dunes. Text, The linear dunes and zibars in this region are far younger. The linear dunes run in long lines down the western edge of the field, and the zibars cross between them.
 
Zibars likely formed from coarser sand settling in the valley as the linear dunes migrate eastward.
 
All of the dunes are made of sand derived from ancient Lake Cahuilla, which has existed in this area intermittently for thousands of years.
 
To learn more, go to earth observatory dot nasa dot gov.