Growth of ripples over time… a long time.

A piece of Mars: Normally I post color images, but this one is just too cool to skip. These ripples formed ages ago: long enough ago that the impact of several small bolides formed craters (seen on the left), disrupting this ripple field (the largest crater is ~85 m across). After the impact, small ripples formed inside the craters, but they never grew to the same size as the original ripples. (HiRISE ESP_033717_1990, NASA/JPL/Univ. of Arizona)