"In some cases, NPS installs interpretive signage to explain that vandalism has taken place and to warn visitors against inflicting additional damage. " Additional damage. Additional means extra, and that means that a lot of looting has taken place there.
"What is being done about this erosion of the past? Why are legislative efforts of little effect, even counterproductive? Is there a practical solution to the problem?" Penn Museum asks. They also state, "...looting of archaeological remains destroys those sites without any record whatsoever, let alone any record of the context from which artifacts are wrenched. " The truth is, what are we doing about looting? How hard are we really trying? Archeologists definitely are trying, but who else can help?
A quote from World Customs Organization, “The looting of cultural heritage has been happening since the very existence of cultural heritage, it is not anything new, but what we see now is that looting has become highly organized and is now a big problem.” This just shows how bad we have let looting get, and now, we're having trouble putting an end to it.
"From temple thieves in India to church pillagers in Bolivia to hundred-man bands of tomb raiders in China’s Liaoning Province, looters are strip-mining our past."