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Published July 2010 | public
Journal Article

Supraglacial and proglacial valleys on Amazonian Mars

Abstract

Abundant evidence exists for glaciation being an important geomorphic process in the mid-latitude regions of both hemispheres of Mars, as well as in specific environments at near-equatorial latitudes, such as along the western flanks of the major Tharsis volcanoes. Detailed analyses of glacial landforms (lobate-debris aprons, lineated valley fill, concentric crater fill, viscous flow features) have suggested that this glaciation was predominantly cold-based. This is consistent with the view that the Amazonian has been continuously cold and dry, similar to conditions today. We present new data based on a survey of images from the Context Camera (CTX) on the Mars Reconnaissance Orbiter that some of these glaciers experienced limited surface melting, leading to the formation of small glaciofluvial valleys. Some of these valleys show evidence for proglacial erosion (eroding the region immediately in front of or adjacent to a glacier), while others are supraglacial (eroding a glacier's surface). These valleys formed during the Amazonian, consistent with the inferred timing of glacial features based on both crater counts and stratigraphic constraints. The small scale of the features interpreted to be of glaciofluvial origin hindered earlier recognition, although their scale is similar to glaciofluvial counterparts on Earth. These valleys appear qualitatively different from valley networks formed in the Noachian, which can be much longer and often formed integrated networks and large lakes. The valleys we describe here are also morphologically distinct from gullies, which are very recent fluvial landforms formed during the last several million years and on much steeper slopes (∼20–30° for gullies versus ≪10° for the valleys we describe). These small valleys represent a distinct class of fluvial features on the surface of Mars (glaciofluvial); their presence shows that the hydrology of Amazonian Mars is more diverse than previously thought.

Additional Information

© 2010 Elsevier Inc. Received 21 September 2009; Revised 24 February 2010; Accepted 28 February 2010; Available online 11 March 2010. We thank David Baker, Seth Kadish, Ailish Kress, Gareth Morgan, and Sam Schon for helpful discussions and John Huffman for assistance in stereo analysis and visualization. This work was supported in part by the Mars Data Analysis Program (MDAP NNGO4GJ99G), the Mars Fundamental Research Program (MFRP GC196412NGA; NNX06AE32G), the Applied Information Systems Research Program (AISR NNXO8AC63) and the Mars Express High Resolution Stereo Camera investigation (JPL 1237163), which are gratefully acknowledged. We also acknowledge the efforts of the MRO CTX science and engineering teams for obtaining data without which this study would not have been possible.

Additional details

Created:
August 22, 2023
Modified:
October 23, 2023