Dartmouth Events

"Paleoenvironmental constraints from quantitative sedimentology and geomorphology: Canyon erosion and sand-ripple formation on Mars." by Mathieu Lapotre, Ph.D., A John Harvard Distinguished Science Fellow from Harvard University.

Abstract: The geologic records of terrestrial planets in our Solar System attest to the volatility of habitability. The history of Mars, in particular, is one of dramatic change that transformed a hospitable environment into the barren land we know today. Deciphering Mars’ geologic past using data from orbiting and landed spacecraft requires using and adapting theory and techniques that were developed for Earth. In return, Mars offers a unique test for Earth-based theory under alien boundary conditions. In this presentation, I will demonstrate how a mechanistic understanding of surface processes sheds light onto Martian paleohydrology and paleoclimate through two examples: the erosion of bedrock canyons by water, and the formation of sand ripples by winds. I will first question the classic assumption that Martian bedrock canyons formed from groundwater-seepage erosion, and show that surface water flows carved those canyons instead. Second, I will present a unifying theory for sand-ripple formation across fluids that can explain the ubiquity of anomalously large eolian ripples on modern Mars and help constrain atmospheric conditions on ancient Mars. Altogether, our results have surprising implications for our understanding of terrestrial landscapes and Mars’ potential as a refugium for early life in the Solar System.