30 C.F.R. § 762.5
For purposes of this part:
Fragile lands means areas containing natural, ecologic, scientific, or esthetic resources that could be significantly damaged by surface coal mining operations. Examples of fragile lands include valuable habitats for fish or wildlife, critical habitats for endangered or threatened species of animals or plants, uncommon geologic formations, paleontological sites, National Natural Landmarks, areas where mining may result in flooding, environmental corridors containing a concentration of ecologic and esthetic features, and areas of recreational value due to high environmental quality.
Historic lands means areas containing historic, cultural, or scientific resources. Examples of historic lands include archeological sites, properties listed on or eligible for listing on a State or National Register of Historic Places, National Historic Landmarks, properties having religious or cultural significance to Native Americans or religious groups, and properties for which historic designation is pending.
Natural hazard lands means geographic areas in which natural conditions exist which pose or, as a result of surface coal mining operations, may pose a threat to the health, safety or welfare of people, property or the environment, including areas subject to landslides, cave-ins, large or encroaching sand dunes, severe wind or soil erosion, frequent flooding, avalanches and areas of unstable geology.
Renewable resource lands means geographic areas which contribute significantly to the long-range productivity of water supply or of food or fiber products, such lands to include aquifers and aquifer recharge areas.
Substantial legal and financial commitments in a surface coal mining operation means significant investments that have been made on the basis of a long-term coal contract in power plants, railroads, coal-handling, preparation, extraction or storage facilities, and other capital-intensive activities. Costs of acquiring the coal in place, or the right to mine it alone without other significant investments, as described above, are not sufficient to constitute substantial legal and financial commitments.
30 C.F.R. §762.5