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Martian channels and valleys - Their characteristics, distribution, and ageThe distribution and ages of Martian channels and valleys, which are generally believed to have been cut by running water, are examined with particular emphasis on the small branching networks referred to as runoff channels or valley networks. Valleys at latitudes from 65 deg S to 65 deg N were surveyed on Viking images at resolutions between 125 and 300 m. Almost all of the valleys are found in the old cratered terrain, in areas characterized by high elevations, low albedos and low violet/red ratios. The networks are deduced to have formed early in the history of the planet, with a formation rate declining rapidly shortly after the decline of the cratering rate 3.9 billion years ago. Two types of outflow channels are distinguished: unconfined, in which broad swaths of terrain are scoured, and confined, in which flow is restricted to discrete channels. Both types start at local sources, and have formed episodically throughout Martian history. Fretted channels, found mainly in two latitude belts characterized by relatively rapid erosion along escarpments, are explained by the lateral enlargement of other channels by mass wasting.
Document ID
19820035949
Document Type
Reprint (Version printed in journal)
Authors
Carr, M. H. (Geological Survey Menlo Park, CA, United States)
Clow, G. D. (U.S. Geological Survey Menlo Park, CA, United States)
Date Acquired
August 10, 2013
Publication Date
October 1, 1981
Publication Information
Publication: Icarus
Volume: 48
Subject Category
LUNAR AND PLANETARY EXPLORATION
Distribution Limits
Public
Copyright
Other