Cool Trip!
Spent a summer on the Rez near
Ft. Defiance , I was Eleven and visited many sites as my Aunt collected pot Shards.
She Made Some Wonderful Mosaics with them.
It gave me a Keen eye for spotting old established sites.
Could that have been remains of chamber pots?
Instead of emptying the chamber pots, the natives just smashed them in a pile since they had so many chamber pots and that was their industry?