Valles Marineris; The Grand Canyon of Mars
The Valles Marineris is a system of
canyons located just south of the Martian equator. The system is about 4000
km long, and, if on earth, would extend all the way across the United States. The central individual troughs,
generally 50 to 100 km wide, merge into a depression as much as 600 km wide. In places the canyon floor reaches a depth of 10 km, 6 to 7 times
deeper than the Grand Canyon. The
geologic history of the central canyon system is complex: first the surface collapsed into a few deep depressions that later
became filled with layered material, perhaps as lake deposits.
Then graben-forming faults cut across some of the older troughs thus
widening existing troughs, breaching barriers between troughs, and forming
additional ones. At that time the
interior deposits were locally bent and tilted, and perhaps water, if still
present, spilled out and flowed toward
the outflow channels. Huge
landslides fell into the voids created by the new grabens. Wind-drifted material, mostly dark in color, apparently still
moves along the canyon floor and locally forms conspicuous dunes. We
have created images of the martian canyon, primarily in the central region,
Ophir and Candor Chasmata, by merging Viking images with topographic maps. Maps
of Ophir and central Candor Chasmata are derived from stereo images by
photogrammetry. They have 200-m
contour interval, except for local gaps that have 1-km contour interval.
West Candor Chasma has 1-km contour interval.
The three-dimensional anaglyph images generated using locally produced
MIPS software (Mini Image Processing System) require red and blue glasses to
view.
A Geographic Information System (GIS) software package (ArcInfo) was
used to super-impose several layers of information, specifically geologic
units, geologic structures, images, and topography.
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