PIA03840: Reull Vallis Source Region


Reull Vallis Source Region

Caption:


(Released 1 July 2002)
The jumbled, chaotic terrain in this THEMIS image may represent a source region for the Reull Vallis, one of the larger channel systems in the southern hemisphere of Mars. Such regions of chaos are thought to form by the catastrophic release of groundwater. If this was the case, then the water would have flowed down gradient to the south and may have contributed to the formation of the Reull Vallis. The top of the image shows two short segments of channels that are interrupted by the chaos, demonstrating that there was a channel system in place before the ground foundered to produce the chaos. One of the more intriguing features seen among the jumbled blocks are narrow ledges that vaguely resemble bath tub rings in the way they conform to the topography. Two good examples are seen running roughly left-right across the image about a fourth of the way down. At first they appear to be layers protruding from the cliff faces, but upon closer inspection a more ledge-like character is evident. Note how they appear different between the south-facing and north facing cliffs. The occurrence of one of these features on the south-facing interior rim of the largest crater in the image but nowhere else around the rim argues against the idea that the ledges are due to a layer of rock cropping out throughout the landscape. Instead, they appear more like the edges of a layer of sediment that drapes the topography. It is possible that the sediment is mixed with ice and is best preserved in the shadowed portions of the terrain. There is no easy explanation for these unusual features. They represent one more Martian enigma.

Cataloging Keywords:

Name Value Additional Values
Target Mars
System
Target Type Planet
Mission 2001 Mars Odyssey
Instrument Host Mars Odyssey
Host Type Orbiter
Instrument Thermal Emission Imaging System (THEMIS)
Detector
Extra Keywords Crater, Grayscale, Shadow, Water
Acquisition Date
Release Date 2002-07-03
Date in Caption 2002-07-01
Image Credit NASA/JPL/Arizona State University
Source photojournal.jpl.nasa.gov/catalog/PIA03840
Identifier PIA03840