The hyperarid, cold-polar desert of the Dry Valleys of Antarctica has long been known to be one of the most Mars-like environments and landscapes on Earth. Indeed it is commonly viewed as a relatively fixed cold polar desert with little internal variation. However, our recent analyses have shown that there are three fundamentally different microclimate zones within this general 'stereotypical' cold polar desert, and that these zones may hold the keys to climate change and landscape evolution on Mars. We are conducting an analysis of the details of the microenvironments and microclimate zones in the Dry Valleys, how these are manifested in geomorphic features, and how these observations can be used to further understand atmospheric, climatological and geological processes on Mars.
Specifically, we are documenting the range of surficial geomorphic processes in microclimate zones in the Dry Valleys and showing how these can be used to improve the understanding of environments on Mars. These analyses will help in the interpretation of a range of geomorphic features on Mars (e.g., different types of polygons, rock glaciers, solifluction and gelifluction lobes, sublimation tills, duricrusts, etc.) and more specifically will help to link them to current and ancient climate zones.
We are assessing how many of the Dry Valleys features can shed light on late Amazonian climate change on Mars. For debris-covered glaciers, for example, we have undertaken field studies to document the surface evolution of the Mullins valley glacier. We have studied the development and evolution of polygons on its surface and we have measured the ages of the rocks on its surface to assess its very slow rate of movement. We have also undertaken preliminary seismic and GPR assessments of its 3-D structure and found hints that below the surface till layer it is composed of nearly pure ice down to bedrock (~ 150 m in one place). Along with our collaborator James Head, Brown University, we have begun to address how these characteristics can be applied to the interpretation of viscous flow features and lobate debris aprons on Mars. One of the major questions in both Earth and Mars glacial geology is whether debris covers on ice deposits can protect underlying ice from vapor diffusive loss over extended periods off time. We were able to begin to address this question in the ADV, instrumenting the debris layer overlying buried ice in Mullins Valley, showing how it can be preserved for millions of years and pointing out how this might be applicable to Mars conditions. Data loggers were also deployed throughout the three microclimate zones in the Dry Valleys to understand better the nature and spatial distribution of the active layer (defined as a near-surface layer that undergoes freeze-thaw cycles due to surface/soil temperatures oscillating about the freezing point of water). A wet active layer undergoes significant yearly geomorphic change through cryoturbation, but a “dry” active layer may occur in soils without free water or ice. We explored the application of these concepts and data to Mars, showing that a wet active layer is currently absent on Mars, but may have been present millions of years ago.
(* = Student Advisee)