October 23, 2012
Valles Marineris – The Grandest Canyon In The Solar System
April Flowers for redOrbit.com - Your Universe Online
One of the most awe-inspiring sights on the planet Earth is the Grand Canyon. The Colorado River has cut through 2 billion years of geologic history, carving out a canyon that is 277 miles long and up to 18 miles wide. However, next to Valles Marineris on Mars, the Grand Canyon is a mere scratch in the ground.
The image above is a bird's-eye view compiled from the data collected on 20 individual orbits of the European Space Agency's (ESA) Mars Express, displayed in near-true color. The image has a vertical exaggeration of four times normal.
The complex geological history of the region is reflected in the wide variety of geological features visible in the image.
The formation of Valles Marineris is probably linked intimately with the formation of the Tharsis bulge, which is just out of shot on the left of this image. The Tharsis bulge is home to the largest volcano in the Solar System, Olympus Mons.
The nature of the rocks located in the walls of the canyon and the surrounding plains reveal the volcanic activity of the region, as they were all built by successive lava flows. During Mars' first billion years, the Tharsis bulge swelled with magma, stretching the surrounding crust. The crust was ripped apart and eventually collapsed into the Valles Marineris.
The imposing extensional forces created intricate fault patterns, the most recent of which are evident in the middle of the image and along the lower boundary. Another factor that played into shaping the canyon is landslides, especially in the northern-most troughs. There, material has recently slumped down the steep canyon walls. The highest part of the walls have been delicately eroded through mass wasting.
After its formation, Valles Marineris may have been reshaped by water, deepening the canyon. Orbiting spacecraft, including Mars Express, have collected mineralogical information showing that the terrain here was altered by water hundreds of millions of years ago.