Mars Global Surveyor
Mars Orbiter Camera
General Comparison of Grand Canyon and Gale Crater
Central Mound Geologic Cross Sections
MGS MOC Release No. MOC2-265L, 4 December 2000
This sketch compares the thickness of the section of layered rocks
exposed in the walls of the Grand Canyon in Arizona with that of the
layered mound in central Gale Crater. In the case of the Grand Canyon,
rocks portrayed as horizontal in the diagram were formed within the
past half-billion years. Rocks that are tilted (dipping) are
more than a billion years old. Comparable thickness does not
necessarily mean comparable age, as different processes and time
scales are involved in the formation of each rock unit, and there are
gaps in the geologic record when rocks were not formed (both in Gale
Crater and in the Grand Canyon). On the other hand, even on a
intensely geologically active planet like the Earth (and in a place
such as the Colorado Plateau where the Grand Canyon is located), it
took many hundreds of millions of years to create sedimentary rock
deposits of the thickness comparable to those observed in the martian
crater. So it is likely the martian rocks record a considerable
amount of time. Equally interesting are the timescale and processes
responsible for erosion. We know in the Grand Canyon that downcutting
by the Colorado River and subsequent mass movements to widen it were
responsible for exposing the rocks there. What processes caused the
rocks in Gale Crater to be eroded such that there is now a 2-4 km
(1.2-2.5 mi) high mound of layered sedimentary rock left in its
center? No one knows.
For additional views of Gale Crater's rocks, see:
For an additional view of the Grand Canyon, see:
Image Credit: NASA/JPL/Malin Space Science Systems
Malin Space Science Systems and the California Institute of
Technology built the MOC using spare hardware from the Mars Observer
mission. MSSS operates the camera from its facilities in San Diego,
CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project
operates the Mars Global Surveyor spacecraft with its industrial
partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA
and Denver, CO.
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