Sand Dunes on Titan

Unlike Earth where sand is the result of weathering and break down of rocks and a lot of other junk. On Titan their sand may be the result of hydrocarbons falling out of the atmosphere and collecting onto sand grain size particles. Recently the orbiter Cassini did another fly by of titan revealing more about the fundamental processes that shape its surface. Information sent back from Cassini shows that the particles are the same complex organic chemicals that make up Titan's atmosphere and that they may contain even less water ice than the rest of Titan. When these particle fall to the ground they are believed to go through a process called sintering which is a slight melting the then welds the particles together allowing them to grow into the perfect size to be blown in the wind and form dunes. This replaces the old idea that most the surface material is water ice with rivers of methane flowing through it, instead it looks like the surface is made mainly of hydrocarbons still with river channels of methane.

http://www.saturndaily.com/reports/Titan_Smoggy_Sand_Grains_999.html