Re-Evaluation of Large Martian Ripples in Gale Crater: Granulometric Evidence for an Impact Mechanism and Terrestrial Analogues

Abstract

Mars hosts three scales of superimposed aeolian bedforms: small decimeter-scale impact ripples, large meter-scale ripples, and dunes. The formation mechanism for large meter-scale ripples is enigmatic and debated. This debate is largely informed by two questions: (a) Are large ripples similar to any features on Earth? and (b) Do they have the same grain size distribution as dunes and impact ripples? We address these questions using a novel digitizing approach to produce the largest known data set of Mars ripple sand grain size to date. We find a distinction between the grain size distributions of small ripples and large ripples and suggest that analogous bedforms are found on Earth. Despite an inability to perform rigorous sedimentology on Mars, results help resolve outstanding questions in bedform physics and support a hypothesis that aeolian ripples on Mars develop by a terrestrially analogous impact mechanism.