MODERN MARS ACTIVITY, DRIVEN BY GRAVITY, WIND, AND FROST (Invited Presentation)

During the Amazonian period, processes related to frost and atmosphere have become the dominant forces shaping the martian surface. The effects of many such processes have become readily visible in the present-day, in large part due to acquisition of repeat, high-resolution images, yielding detailed measurement and characterization of small-scale surface changes. Observed (and heavily studied) changes include dune and ripple evolution and migration, mass-wasting within gullies and dune-alcoves, and scouring due to high-pressure gas flow under seasonal ice layers. While some of the landforms and even evidence of activity were seen earlier, recent studies of these surface changes have yielded improved estimates of activity rates and timing, and have changed working models of how and how much of a role seasonal CO2 frost plays in initiating and enhancing surface morphological changes (in many cases, instead of liquid water-driven flow). These studies have also updated our understanding of how frost, wind, and gravity interact within these processes. In this presentation, we will give an overview of small-scale surface changes that have been observed on Mars, and as possible tie these changes and resultant landforms to formative processes and environmental conditions. We will also reflect on what has enabled major advances in our understanding of martian processes (at least in the present-climate) and identify what will be needed to address key open questions about modern Mars activity.