How Old are Rocks on Mars?
NASA/JPL/University of Arizona
How Old are Rocks on Mars?
ESP_020945_1690  Science Theme: Geologic Contacts/Stratigraphy
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Some of the largest landslides known in the Solar System have happened on Mars. These are interesting phenomena, but they also sometimes produce excellent exposures of the bedrock geology, in cross-sectional views. The purpose of this image was to view bedrock exposures at a deep level in Valles Marineris.

We have only a vague idea how old these rocks are. Crater counts date landscapes, and clearly this is a young landscape with very few impact craters due to the continual mass wasting (landslides) of the steep slopes. The rocks are much older--probably older than the plateaus surrounding Valles Marineris (2 to 3 billion years based on the large craters), unless these are intrusive rocks emplaced later from migrating magma. We need radiometric age dating, either on Mars or from returned samples, to measure the age of igneous (volcanic or plutonic) rock layers within the strata.

The age of sedimentary layers such as river or lake deposits can be bracketed by the ages of overlying and underlying igneous layers. Not knowing the absolute ages of bedrock units on Mars is a huge limitation to our understanding of the geologic history.

Written by: Alfred McEwen   (16 February 2011)

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Acquisition date
14 January 2011

Local Mars time:
15:36

Latitude (centered)
-10.774°

Longitude (East)
292.118°

Range to target site
264.8 km (165.5 miles)

Original image scale range
53.0 cm/pixel (with 2 x 2 binning) so objects ~159 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection
Equirectangular

Emission angle:
5.0°

Phase angle:
47.7°

Solar incidence angle
53°, with the Sun about 37° above the horizon

Solar longitude
217.2°, Northern Autumn

North azimuth:
98°

Sub-solar azimuth:
355.6°
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NASA/JPL/University of Arizona



Postscript
For information about NASA and agency programs on the Web, visit: http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.