Online Astronomy eText: Moons of Saturn
Geologic Map of Titan Link for sharing this page on Facebook
Page created Nov 19, 2019

 A geologic map of Titan, based on Cassini radar, infrared and visual images taken between 2004 and 2017 (Image Credit NASA/JPL-Caltech/ASU). As shown in the color index at the bottom, different types of areas are represented by different colors. "Plains" are broad, relatively flat regions, "labyrinth" areas are tectonicaly disrupted regions often containing fluvial (river-like) channels formed by streams of liquid methane and/or ethane, "hummocky" areas are hilly, with some mountains, "dunes" are mostly linear dunes produced by winds in Titan's atmosphere, "craters" are impact features, and "lakes" are regions now or previously filled with liquid methane or ethane (in some cases, as much as 100 meters in depth). The dunes are mostly scattered along the Equator, where wind velocities are highest (usually winds are only 2 to 4 miles per hour, but apparently there are occasional gusts well in excess of those speeds), while lakes are primarily near the poles, particularly the North Pole.
 As spring and summer approach many of the Northern lakes are disappearing, as their liquids evaporate into the atmosphere. Because Titan's rotation is locked to its orbit around Saturn, its seasons are the same as those on Saturn, which take nearly 30 years for a full cycle (one of Saturn's orbits around the Sun). The predominance of lakes near the North Pole may be due to the fact that it was winter there when Cassini first reached the planet, making it easier for liquid methane and ethane raindrops to fall to the surface. Now that it is spring and heading into summer, the Northern lakes appear to be evaporating, and it may be that as it reaches summer in the Northern hemispher and winter in the Southern hemisphere, lakes may become more common in the South than in the North, but since the Cassini spacecraft is no longer orbiting the planet, it may be quite a while before we know.
Note: On the Earth a geologic map means a representation of the subsurface geology; but in this case, and in the case of all objects in the Solar System, it means a representation of the different kinds of topographic features and/or their apparent surface mineralogy. In Titan's case, save for the lakes, everything is simply water ice that is as hard as a rock, due to the very low surface temperature. However, some areas which can be thought of as "sandy" may consist of grains of water ice with a thin coating of liquid methane or ethane, as seen in the Huygens images of its landing site.