36 C.F.R. § 62.2
The following definitions apply to this part:
National Natural Landmark is an area designated by the Secretary of the Interior as being of national significance to the United States because it is an outstanding example(s) of major biological and geological features found within the boundaries of the United States or its Territories or on the Outer Continental Shelf.
National Registry of Natural Landmarks is the official listing of all designated national natural landmarks.
National significance describes an area that is one of the best examples of a biological community or geological feature within a natural region of the United States, including terrestrial communities, landforms, geological features and processes, habitats of native plant and animal species, or fossil evidence of the development of life.
Natural region is a distinct physiographic province having similar geologic history, structures, and landforms. The basic physiographic characteristics of a natural region influence its vegetation, climate, soils, and animal life. Examples include the Atlantic Coastal Plain, Great Basin, and Brooks Range natural regions.
Owner means the individual(s), corporation(s), or partnership(s) holding fee simple title to property, or the head of the public agency or subordinate employee of the public agency to whom such authority was delegated and who is responsible for administering publicly owned land. Owner does not include individuals, partnerships, corporations, or public agencies holding easements or less than fee interests (including leaseholds) of any form. A Native American tribe that is the beneficial fee simple owner of lands, with the United States as trustee, will be considered as owner of private property for the purposes of this part. Similarly, individual member(s) of a Native American tribe who are beneficial owner(s) of property, allottee(s) held in trust by the United States, will be considered as owner(s) of private property for the purposes of this part.
Potential national natural landmark means an area that, based on recommendation or initial comparison with other areas in the same natural region, seems to merit further study of its merits for possible national natural landmark designation.
Prejudicial procedural error is one that reasonably may be considered to have affected the outcome of the designation process.
Representative refers to any public or private individual, agency, or organization that is performing actions related to the identification, evaluation, designation or monitoring of national natural landmarks on behalf of or in cooperation with the National Park Service (NPS), either under a contractual agreement or as a volunteer.
Scientist refers to an individual whose combination of academic training and professional field experience in the natural region qualifies him/her to identify and comparatively evaluate natural areas at the regional or national level.
36 C.F.R. § 62.2