A quote:

The typical size of sand grains is remarkably constant, whether one looks at Titan, Mars, or Earth, adds Ronald Greeley, a planetary geologist at Arizona State University in Tempe. The grains are roughly the size of granulated sugar. With colleague James Iverson, Dr. Greeley ran lab experiments in the 1980s that suggested Titan's winds might be strong enough to move material around the surface. The new images confirm that work.

“It's great fun to think about one fundamental process operating in such drastically different environments,” he says. The source of Titan's sand remains a puzzle. The team so far has failed to find any obvious ones. One possibility: The supply of sand-like grains have built up over the moon's 4.5 billion-year-history through sunlight-driven chemical reactions in Titan's stratosphere. The resulting particles could have rained to the surface over time. Or, liquid methane flowing on the surface could erode exposed formations of ice “bedrock.”

Where that would occur is unclear, given the absence so far of images of fluids. But images from the European Huygens lander, as well as from Cassini, show features in boulders and the landscape shaped by fluids.

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