Without doubt, the putative paleo-Oceanus-Borealis-on-Mars model has taken some hits this year in the literature. For example,

Withers, P. and G.A. Neumann, Enigmatic ridges on the plains of Mars, Nature, 410, 652, 2001.
http://ltpwww.gsfc.nasa.gov/tharsis/withers.ridges.pdf

Withers and Neumann report that terraced features near the Utopia impact basin and Alba Patera, interpreted by Head et al. [1999] as possible paleo-ocean shorelines, are in their opinion tectonic features. In addition to a reversal of shoreline morphology from one side of the putative "ocean" to the other (which the authors find highly improbable with known shoreline forming processes), Withers and Neumann also note that the majority of the ridge features that crisscross the northern plains are correlated to major stress centers (e.g. Tharsis, Utopia, Alba Patera, etc.). In fairness, though, Paul Withers has told me that others should not "overinterpret" the results. We really do not know what Gyr shorelines would look like in any event.

Perusing the recent literature, one might observe that Head et al. seem to be giving out mixed signals on this issue. In a 32nd LPSC abstract in the print-only presentations

(see http://www.lpi.usra.edu/meetings/lpsc2001/pdf/1064.pdf),

they seem to be backpedaling from their earlier claims and note the lack of confirming evidence from other workers. Indeed, the best that they can state is "...some properties of Contact 2 are consistent with the Parker et al. hypothesis." Indeed, one will note the recent paper

Ivanov, M.A. and J.W. Head, 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, J Geophys Res 106, 3275-3295 (2001).

where Ivanov and Head discuss the plausibility of a standing body of water in Chryse Planitia. The authors report that MOLA altimetry measurements at the mouths of six major circum-Chryse Hesperian-aged outflow channels (Kasei, Maja, Simud, Tiu, Ares, and Mawrth Valles) debouch/terminate into Chryse at elevation variations of ~170m, spanning a lateral distance of 2500 km. Moreover, the channel termini disappear within 190 m of Parker's Contact 2. While not conclusive, this result is suggestive that the channels emptied into a body (presumably water) with a highstand very near to Contact 2.

Personally, I have a little more to say on the issue, which I'll be detailing in a future article for SpaceDaily, probably after the work Nick and I are collaborating together on regarding the GeoMars 2001 Conference and my upcoming month long trip to France. In any event, I'll try to rehabiliate the Oceanus Borealis model with a little help from others such as Clifford and Parker, who have a paper in press with Icarus

The Evolution of the Martian Hydrosphere: Implications for the Fate of a Primordial Ocean and the Current State of the Northern Plains, by S. M. Clifford and T. J. Parker, Icarus, in press.
For a preprint, see http://www.lpi.usra.edu/meetings/geomars2001/evolution.pdf

and lay out a case for rebutting the Malin and Edgett results from 1999

see http://www.msss.com/mars_images/moc/grl_99_shorelines/index.html

For me, the battle has just begun, but as Apollo 16 CMP Ken Mattingly said, "I guess it's back to the drawing board, or wherever geologists go." ;-)

Alex R. Blackwell
University of Hawaii