Martian Gullies and Their Connection With the Martian Climate

Conway, Susan J.; Harrison, Tanya N. and Lewis, Stephen R. (2018). Martian Gullies and Their Connection With the Martian Climate. In: Soare, Richard J.; Conway, Susan J. and Clifford, Stephen M. eds. Dynamic Mars: Recent and Current Landscape Evolution of the Red Planet. Elsevier, pp. 87–119.

DOI: https://doi.org/10.1016/B978-0-12-813018-6.00003-0

Abstract

Since the discovery of gullies on Mars nearly two decades ago, their study has evolved significantly. Initially, they were hailed as evidence of active liquid water martian aquifers; were this assumption valid, the aquifers could represent a significant reservoir of liquid water. This conclusion was tempered by global data, revealing intriguing climatic signals interpreted to signify an episodic top-down melting scenario, indicating a more modest hydrosphere. Recently, authors have favored completely dry gully formation engendered by an exotic solid CO2 sublimation mechanism never before observed on any other planetary surface suggesting a desert planet. This chapter will not only review these end-member formation hypotheses but also will critically examine them in light of all currently available population-scale data and new climate simulations. We conclude that neither water nor CO2 can explain the observational data for martian gullies, but that water is consistent with more of the observational data.