Cassini Regio

The dark hemisphere of Iapetus, first detected by Giovanni Cassini, who noticed Iapetus was brighter when on one side of Saturn. Possibly formed due to different rates of sublimation of ices or as dark material landed their from Phoebe.

Web Pages

 * http://en.wikipedia.org/wiki/Cassini_Regio

Collision Formation Theory for Equatorial Ridge (May 2011)

 * http://news.discovery.com/space/iapetus-fights-the-battle-of-the-bulge-110523.html

Material From Phoebe Created Dark Side of Iapetus (Jul 2011)

 * http://www.sciencenews.org/view/generic/id/332324/title/Iapetus_gets_dusted