Valles Marineris, the grand valley of Mars named after the
Mariner program which first took close-up images. Click on image
for full size Image from: USGS Valles Marineris is a large
system of canyons, shown in this image, that stretches 4000 km
(2500 mi) along the equator of Mars. It was first imaged in
detail by Mariner 9. The scene to the left (centered at: lat -8,
long 78) shows the entire Valles Marineris canyon system, over
2000 kilometers long and up to 8 kilometers deep. This system
extends from Noctis Labyrinthus (check the large topographic map
of Mars) - the arcuate system of grabens to the west, to chaotic
terrain to the east. As can be seen in the image, many huge
ancient river channels originate at chaotic terrain, from north-
central canyons in the image, and extend north. The three
Tharsis volcanoes (dark red spots), each about 25 kilometers
high, are visible on the leftmost (western) edge of the image.
To the south are the highlands; very ancient terrain, covered by
many impact craters. High r