Not offhand, but there are many prehistoric examples in NPS control. For
example, entire areas of Mesa Verde NP are off limits to the public or
carefully regulated due to preservation concerns. Staffing does not permit
adequate supervision of visits to these sites in more remote areas. This is a
tacit recognition of the fact that public ownership and access do not always
conincide with preservation. In fact, public access can often lead to the
site's destruction or increased vandalism.
RLH