Outflow Channels May Make a Case for a Bygone Ocean on Mars
Written by Linda M.V. Martel
Hawai'i Institute of Geophysics and Planetology

High-resolution elevation data from the Mars Orbiter Laser Altimeter (MOLA) onboard the Mars Global Surveyor (MGS) spacecraft have been analyzed recently in Chryse Planitia to test the hypothesis that large outflow channels emptied into an ocean in this region of Mars. Researchers Mihail (Misha) Ivanov (Vernadsky Institute of Geochemistry and Analytical Chemistry) and James Head (Brown University) collected quantitative MOLA information on channel patterns, continuity, and elevations where those patterns change or
disappear into the northern lowlands. Their recently published report describes how the channels end, or become more subtle, at elevations very close to a previously mapped geologic contact interpreted by some to represent a shoreline of an ancient ocean. Ivanov and Head
hypothesize that the change in channel topography is consistent with flow of water from a river into a submarine environment with possible deposition of sediments by density currents deep into the North Polar basin.

Reference:

Ivanov, M. A. and J. W. Head, III (2001) Chryse Planitia, Mars: Topographic configuration, outflow channel continuity and sequence, and tests for hypothesized ancient bodies of water using Mars Orbiter Laser Altimeter (MOLA) data, Journal of Geophysical Research, vol.106, p. 3275-3295.
Reprint (pre-print) available at
http://128.148.116.39/pubs_pdf/2369.pdf

For full story, see
http://www.psrd.hawaii.edu/June01/MarsChryse.html

Alex R. Blackwell
University of Hawaii