Spacecraft observations of Mars show different physical properties of layers in a region called Terra Meridiani. These differences suggest that the environment on this part of Mars varied through time as these layers were formed.
NASA / JPL / Arizona State University
Delve into this topic through author Scott Kenyon’s web site, which includes links to interviews, popular articles and journal papers. Quicktime animations illustrate the evolution of bright rings of dust in a disk where icy planets form.