The wind has been found to generally uncover things from time to time. The soil on the surface is so dry and fine that it takes a very long time for dust sediment to “settle” or harden, as it would on earth due to moisture condensing from the air. Mars has very little frost, no significant organic decay of minerals, so there is not as much tendency for things to get buried.

Basically all that life and moisture on earth makes everything kind of sticky. Mars is far less “sticky.” Something can be covered up, only to be completely uncovered again as the wind continues.