525 ILCS 5/2

As used in this Act, the following terms have the following meanings, unless the context otherwise requires: "Cave" means any naturally occurring void, cavity, recess, sinkhole or system of interconnecting passages beneath the surface of the earth or within a cliff or ledge which is large enough to permit a person to enter, including natural subsurface water and drainage systems, but not including any mine, tunnel or other manmade excavation. "Cave resource" means any cave and its contents, together with associated topographic and hydrological features. "Commercial cave" means any cave utilized by the owner for the purpose of exhibition to the general public as a profit or nonprofit enterprise, wherein a fee is collected for entry. "Cultural resource" means any historic or prehistoric human remains, artifacts, constructions or evidence thereof. "Department" means the Department of Natural Resources. "Director" means the Director of the Department. "Gate" means any structure or device located to limit or prohibit access or entry into any cave. "Natural resource" means any material occurring naturally in caves including, but not limited to, animal life, whether vertebrate or invertebrate, plant life, paleontological deposits, sediments, minerals, speleogens, speleothems, water and other natural resources. "Owner" means a person who owns title to land where a cave is located. "Person" means any individual, partnership, firm, association, trust, corporation or other legal entity. "Sinkhole" means a closed topographic depression or basin, generally draining underground, including, but not restricted to, a doline, uvala, blind valley, or sink. "Speleogen" means the surrounding natural material or bedrock in which a cave is formed, including walls, floors and ceiling and similar related structural and geological components. "Speleothem" means a natural mineral formation or deposit occurring in a cave. (Source: P.A. 89-445, eff. 2-7-96.)