Cassini is about 36 miles in diameter with a narrow, relatively low surrounding rim. Note especially on the rectified view below how the shape of Cassini resembles more a polygon than a circle. The exterior slopes shows show a lot of rubble. Why so much debris on the exterior surface compared to the interior surface. Maybe some interior rubble later cover up by lava flows?
This view was made 10 June 2011 at 04:25:13 UT through a IR filter.