@65dBnoise @ryanbanderson @nami_wiki Thinking out loud... Looking at the size of some of the boulders imbedded in the delta deposits there were some pretty cool flooding events that brought material into the crater (debris flows etc), I guess some of these float rocks imaged by the rover could have been transported in from outside the crater, and later liberated from the sedimentary deposits by differential erosion. I know it's best to wait for the official view, but speculation can be fun :)