The Equatorial Ridges of Pan and Atlas - Terminal Accretionary Ornaments?
http://ciclops.org/media/sp/2008/5168_11571_0.pdf
In the outer regions of Saturn’s main rings, strong tidal forces balance gravitational accretion processes.
Thus, unusual phenomena may be expected there. The Cassini spacecraft has recently revealed the strange “flying saucer” shape
of two small satellites, Pan and Atlas, located in this region, showing prominent equatorial ridges. The accretion of ring
particles onto the equatorial surfaces of already-formed bodies embedded in the rings may explain the formation of the ridges.
This ridge formation process is in good agreement with detailed Cassini images showing differences between rough polar and smooth
equatorial terrains. We propose that Pan and Atlas ridges are kilometers-thick “ring-particle piles” formed after the satellites
themselves and after the flattening of the rings but before the complete depletion of ring material from their surroundings.
