Pathfinder site also had high static electric charge.
This explanation does not explain why this cohesive material was not found at the Pathfinder site. But note that the GRS on Mars Odyssey has found high levels of water content *within centimeters of the surface* at both Gusev and Meridiani, perhaps as much as 15% by weight at Meridiani.
Since both Gusev and Meridiani are within the temperature and pressure ranges to permit liquid water, the cementation due to liquid water explanation would fit in well with the data presented by the GRS.
Bob Clark