First, the shards I have found that are large enough to discern are from the middle of the bills.. not the outer edges.
I have not found any examples of tumbling money.. I tried to come with a test but I just can't see how it can be done properly to replicate the conditions and recover the money.
The money sinks but it still has buoyancy like many things other than heavy items like rocks.. I have found images of bills suspended just above the bottom of water. It is reasonable to conclude that the current can roll the money along the bottom. The TBAR section of the Columbia is very flat and sandy with almost no snags.
and all the images of buried money I have found do not have symmetrical damage like TBAR. The damage is very random... nothing like TBAR's uniform erosion.
Also, circulated currency is riddled with bacteria.. even if sand is sterile, the money already had bacteria on it.
It is absurd that the uniformly rounded edges are from bacteria.. There was some bacteria damage on the bills but it is random. Further, why did the bills get rounded only around the outside and NOT through the middle of the stack,,, answer, the erosion was not in situ.
Internal fragments... these are different pieces