Gully formation in the McMurdo Dry Valleys, Antarctica: multiple sources of water, temporal sequence and relative importance in gully erosion and deposition processes
James L. Dickson, James W. Head, Joseph S. Levy, Gareth A. Morgan, David R. Marchant, 2019. "Gully formation in the McMurdo Dry Valleys, Antarctica: multiple sources of water, temporal sequence and relative importance in gully erosion and deposition processes", Martian Gullies and their Earth Analogues, S. J. Conway, J. L. Carrivick, P. A. Carling, T. de Haas, T.N. Harrison
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We report on a decade of fieldwork designed to determine the conditions required for erosion of Mars-like gully channels in the McMurdo Dry Valleys (MDV) of Antarctica. We have outlined the major factors in the morphological evolution of gullies in the Inland Mixed Zone of the MDV: (1) the distribution of ice sources; (2) the temporal aspects of ice melting; and (3) the relative significance of melting events in gullies. We show that significant erosion of gully channels can be achieved if geometrical and environmental conditions combine to concentrate ice where it can rapidly melt. In contrast, annual melting of surface ice and snow deposits during late-season discharge events contribute to transport of water, but flux rarely surpasses the infiltration capacity of the active layer. These small discharge events do not erode channels of significant width. Even when the flux is sufficient to carve a c. 10–20 cm deep channel during late summer (January–February) runoff, these small channels seldom persist through multiple seasons, because they are seasonally muted and filled with aeolian deposits. We briefly discuss the application of these results to the study of gully systems on Mars.
Supplementary material: Eight videos showing activity and events are available at https://doi.org/10.6084/m9.figshare.c.3935992
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Martian Gullies and their Earth Analogues
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Gullies on Mars resemble terrestrial gullies involved in the transport of abundant material down steep slopes by liquid water. However, liquid water should not be stable at the Martian surface. The articles in this volume present the two main opposing theories for Martian gully formation: climate-driven melting of surficial water-ice deposits and seasonal dry-ice sublimation. The evidence presented ranges from remote-sensing observations, to experimental simulations, to comparison with Earth analogues. The opposing hypotheses imply either that Mars has been unusually wet in the last few million years or that it has remained a cold dry desert – both with profound implications for understanding the water budget of Mars and its habitability. The debate questions the limits of remote-sensing data and how we interpret active processes on extra-terrestrial planetary surfaces, even beyond those on Mars, as summarized by the review paper at the beginning of the book.