This false-color mosaic was taken with Spirit's panoramic camera on martian day, or sol, 554 (July 25, 2005), while Spirit was sitting on the "Voltaire" layered rock outcrop. A rock within the Voltaire outcrop, called "Haussmann," exhibited many interesting patterns, including rounded pebbles that are approximately 2 to 3 centimeters (.8 to 1.2 inches) across. The pebbles are embedded in a finer-grained matrix of material. The striations in Haussmann are noted. The rounded pebbles must have been exposed to erosion in the past, before they were embedded into the rock. The layered rocks in this area are thought to have formed from an impact event, as ejected deposits. They illustrate the complexity of the rocks found by Spirit as the rover made its way to the summit of Husband Hill.