Some of the most extensive sandstone deposits in the world were deposited by wind.  How do such aeolian rocks differ from water or ice-deposited rocks?  And  what do they reveal about the environments in which they formed?  In the podcast she describes the dunes we see in the geological record on Earth, as well as on Mars and on a comet, and explains what we've learned from them. Mackenzie Day is an Assistant Professor in the Department of Earth, Planetary, & Space Sciences at the University of California Los Angeles. She is an expert in aeolian processes.  In the podcast she describes the dunes we see in the geological record on Earth, as well as on Mars and on a comet and explains how they formed. Go to geologybites.com for podcast illustrations and to learn more about the series.