The National Natural Landmarks Program encourages the conservation of pieces of natural history in the U.S., including biological and geological features that are privately and publicly owned. Since its inception in 1962 (May 18, to be exact), the program encourages people to participate voluntarily; they are not legally bound to do so, although the NNL Program is governed by the Historic Sites Act of August 21, 1935. It does not have the protection features of Section 106 of the National Historic Preservation Act of 1966, so either party can terminate the agreement upon notifying the other party.According to the passage,