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Morphologic contrasts between Nirgal and Auqakuh Valles, Mars: Evidence of different crustal propertiesPhotoclinometric measurements were made of sidewall slopes in Nirgal and Auqakuh Valles and these results were interpreted in terms of the geologic setting and a simple geomorphic model to provide insights into the physical properties of crustal materials in these areas. Nirgal was interpreted to be a runoff channel and Auqakuh to be a fretted channel. Geomorphologic arguments for the sapping origin of Nirgal and Auqakuh Valles were presented. The morphologies of the channels, however, differ greatly: the tributaries of Nirgal end abruptly in theater-headed canyons, whereas the heads of tributaries of Auqakuh shallow gradually. The plateau surface surrounding both channels appears to be covered by smooth materials, presumably lava flows; they are continuous and uneroded in the Nirgal area, but at Auqakuh they are largely eroded and several layers are exposed that total about 200 m in thickness. For Nirgal Valles, the measurements show that sidewalls in the ralatively shallow upper reaches of the channel have average slopes near 30 degrees and, in the lower reaches, sidewall slopes exceed 50 degrees. Auqakuh, on the other hand, has maximum sidewall slopes of 14 degrees and an approximate maximum depth of 1000 m. Faint, horizontal layering in portions of the lower reaches of Nirgal may indicate inhomogeneity in either composition or topography.
Document ID
19880020297
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Mackinnon, David J.
(Geological Survey Flagstaff, AZ., United States)
Tanaka, Kenneth L.
(Geological Survey Flagstaff, AZ., United States)
Winchell, Philip J.
(Wittenberg Univ. Springfield, Ohio., United States)
Date Acquired
September 5, 2013
Publication Date
January 1, 1987
Publication Information
Publication: Lunar and Planetary Inst., MEVTV Workshop on Nature and Composition of Surface Units on Mars
Subject Category
Lunar And Planetary Exploration
Accession Number
88N29681
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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