Jack - - - that looks like dumped fill material with some "stuff" in it? Ditch cleanings?
It will likely settle in an inconsistent fashion as roots, etc. decompose, and various types of materials (sand, silt, clay) pack in.
Looks like done in large quantities 6+ feet deep on the left side of your picture, where compaction in small lifts is not possible.
Only point it out as your grade may not end up where you started. Compaction of the fill on the left side of your picture would not be productive, as it will only work in the first 6-12" at best. Could be an exciting ride on a roller on/near that slope, too.....