Originally posted by Bass
Maybe this belongs in the "Science Photo of the Week" thread, but the reference to cross-beds in this thread made it relevant.
This photo from the Mars Rover Opportunity near the edge of Erebus Crater shows good evidence for the historical presence of water on Mars- note the "festoons" or cross-laminations (curved upward layers) that indicate water-formed ripples.
Subduction causes orogeny.
Bass, may I politely disagree. I concur that this is evidence for water on Mars, but the structures to me look to be a series of seasonal dessication cracks that are stacked one upon another. To bad we can't get to the outcrop to determine the accuracy of the interpretation.
And orogeny causes uplift