36 C.F.R. § 290.2
For the purposes of this part, the terms listed in this section have the following meaning:
Authorized officer means the Forest Service employee delegated the authority to perform the duties described in this part.
Cave means any naturally occurring void, cavity, recess, or system of interconnected passages beneath the surface of the earth or within a cliff or ledge and which is large enough to permit a person to enter, whether the entrance is excavated or naturally formed. Such term shall include any natural pit, sinkhole, or other opening which is an extension of a cave entrance or which is an integral part of the cave.
Cave resources mean any materials or substances occurring in caves including, but not limited to, biotic, cultural, mineralogic, paleontologic, geologic, and hydrologic resources.
National Forest System lands means all national forest lands reserved or withdrawn from the public domain, acquired through purchase, exchange, or donation, national grasslands and land utilization projects, and other lands, waters, or interests administered by the Forest Service.
Secretary means the Secretary of Agriculture.
Significant cave means a cave located on National Forest System lands that has been determined to meet the criteria in § 290.3 (c) or (d) and has been designated in accordance with § 290.3(e) .
36 C.F.R. §290.2