Exploratour - The Surface of Mars
Valles Marineris
One of the most unusual features on Mars, shown in this image, is named Valles Marineris. Valles Marineris is not just one canyon, but a system of canyons that stretches 4000 km (2500 mi) along the equator of Mars, and is up to 8 kilometers deep.
The picture shows many of the huge and ancient river channels which originate at north and central canyons, and extend north. The three Tharsis volcanoes (dark red spots), are visible on the leftmost (western) edge of the image. To the south are the highlands.
The slopes of the canyons are very steep, and the gullies at the bottom are filled with boulders and other debris. In this way the canyon looks like the Grand Canyon of Arizona. Scientists are not sure how the canyons formed.