March 23, 2004 — This magnified view from Opportunity of a portion of a Martian rock called Upper Dells shows fine layers (laminae) that are truncated, discordant and at angles to each other. This rock, like another called "Last Chance," preserves evidence for trough cross-lamination, likely produced when flowing water shaped sinuous ripples in underwater sediment and pushed the ripples to migrate in one direction. The direction of the ancient flow would have been toward or away from the viewer.