Basically, these are probably hollows in which the guanacos roll around in the dust.

HTH


Sheila


Llamas love to roll in the sand or dust and may create “dust bowls” in order to rid their skin from these external parasites (Birutta 1997).

http://www.susqu.edu/students/b/bowlinge/Vertebrate Natural ...



The guanacos readily take to the water: several times at Port Valdes they were seen swimming from island to island. Byron, in his voyage says he saw them drinking salt water. Some of our officers likewise saw a herd apparently drinking the briny fluid from a salina near Cape Blanco. I imagine in several parts of the country, if they do not drink salt water, they drink none at all. In the middle of the day they frequently roll in the dust, in saucer-shaped hollows.

http://www.peninsulavaldes.org/patagonia/animals/mammals/gua...