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New data from Curiosity has now provided further confirmation that the deeper sedimentary layers seen in Gale Crater were likely formed far in the past by flowing water.
“Paradoxically, where there is a mountain today there was once a basin, and it was sometimes filled with water,” said John Grotzinger, the former project scientist for Mars Science Laboratory at the California Institute of Technology in Pasadena, and lead author of the new report. “We see evidence of about 250 feet (75 meters) of sedimentary fill, and based on mapping data from NASA’s Mars Reconnaissance Orbiter and images from Curiosity’s camera, it appears that the water-transported sedimentary deposition could have extended at least 500 to 650 feet (150 to 200) meters above the crater floor.”
Furthermore, the total thickness of sedimentary deposits in Gale Crater that indicate interaction with water could extend higher still, perhaps up to one-half mile (800 meters) above the crater floor.
Above 800 meters, Mount Sharp shows no evidence of hydrated strata, and that is the bulk of what forms Mount Sharp. Grotzinger suggests that perhaps this later segment of the crater’s history may have been dominated by dry, wind-driven deposits, as was once imagined for the lower part explored by Curiosity.
This was always the reason to go and climb Mount Sharp. As Curiosity heads uphill it begins to map out the geological history of Mars, first as a wet place with liquid water, then as a dry place in which the water is gone.