Cranks claim to find "Out-of-place artifacts" all the time, and most of the claims turns out to be misunderstandings, fraud, etc.
But suppose someone do find something spectacularly different from what we expect to find - say, native American graves from 3000 years ago with Greek artifacts inside.
How would historians and archaeologists go about making sure that the find is real as opposed to a forgery or misunderstanding?
In the case of something as controversial or unprecedented as the Monte Verde site in southern Chile, where the conventional wisdom of "Clovis first" was being upset, leaders of the discipline were invited to see the material in situ at the site. They reported in American Antiquity, the esteemed instrument of the Society of American Archaeology on their observations. New discoveries are often reported on at regional meetings while the work is still underway in order to invite scrutiny. Regional experts will often be invited to the site for personal tours. Following regional reporting, the findings will be published in a peer reviewed journal where skeptics can provide reviews or challenges. Basically, the veracity of new claims is hammered out on the pages of peer reviewed journals.