MAPPING THE PREVIOUS EXTENT OF THE MEDUSAE FOSSAE FORMATION, MARS

The Medusae Fossae Formation (MFF), Mars, is an unconformable deposit that covers ~2.1 x 10⁶ km² of the Martian surface, stretching discontinuously for over 5,000 km between 135 and 235°E and 10°N and 10°S. The thicknesses of present-day MFF outcrops range from tens to thousands of meters. MFF is characterized by internal layering and displays abundant yardangs. Terrestrial yardangs are common in ignimbrites, suggesting that the MFF is composed of similarly fine-grained and differentially indurated materials. The presence of outliers of MFF around the continuous outcrops, and the presence of yardangs, are consistent with the interpretation that the MFF previously covered a larger area, but aeolian processes have eroded the MFF to its current extent. These MFF outliers have yet to be mapped, quantified, or used to interpolate the previous extent of the MFF. Here, we use high-resolution (<25 m/pixel) visible images (primarily Thermal Emission Imaging Spectrometer and Context Camera images) to search for and systematically map MFF outliers. Preliminary results suggest that the MFF once covered an area at least twice that of the contemporary extent. More complete mapping of MFF outliers will be used to constrain erosion rates on the Martian surface.