Nov 17 2005, 03:00 PM
Is Pollack a remnant of a giant crater lake like Gusev?
Pollack Crater and White Rock:
Release: 4 December 2000 - http://www.msss.com/mars_images/moc/dec00_seds/pollack/
Release: 14 November 2005 - http://www.msss.com/mars_images/moc/2005/11/14/
More images - http://images.google.de/images?svnum=10&hs...mars&btnG=Suche
What is White Rocks origin, a sedimentary outcrop? Liquid past?
Nov 17 2005, 07:18 PM
May 19 2006, 08:14 PM
MARS ODYSSEY THEMIS IMAGES
May 15-19, 2006
o Feature of the Week: "White Rock" http://themis.asu.edu/feature
May 19 2006, 09:39 PM
Unfortunately, the White Rock mystery has now been conclusively solved. The TES on MGS provided indications all the way back in 2000 that it's just standard-model Martian dust indurated by some past exposure to very small amounts of water (or sulfuric acid) that cemented the grains, and OMEGA on Mars Express has now conclusively confirmed this: http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1592.pdf
. Even its color is really no lighter than the plains surrounding the crater -- it just looks lighter by contrast with the somewhat darker sediments surrounding it on the crater floor. (The contrast-amplification capability of the Viking cameras was seriously misleading to the human eye on this.)
May 20 2006, 10:14 AM
The layered sediments of Pollack crater are clearly part of a massively eroded regional remnant deposit. Scattered all over a region north and east of the Meridiani layered deposits are apparently unrelated or distantly related deposits in many craters. Big examples are the layered plateaus in Becquerel crater, Henry crater and another next to it in Arabia, and the Pollack crater deposit. Non of them seem to be colorimetrically distinctive, unlike Meridiani materials, in Viking color data. Just bright and reddish. There doesn't seem to be much evidence of the material except as remnants forming isolated plateaus in large craters well separated from the crater walls. But they're thick. The one in Henry crater, in particular is massive.