Collecting Away a Non-Renewable Resource

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You Tube video about the non-sustainability of collecting away a finite resource: "this site has been done".

PeaceHavens assures his fellow artefact hunters: "If you want to find anything you've got to find a new site that's not been detected before" because as he shows, once somebody's taken the surface evidence of human activity in the past from a place, its gone. There is no way of getting that evidence back once it has been discarded, scattered in ephemeral personal collections or flogged off on eBay. Now what he's enthusing about is mostly modern 'byegones', but the same principle applies to a Roman settlement, Early Medieval cemetery or whatever.

What happens when 10 000 + artefact hunters run out of "new sites"?