coal seam
Defined in 1 dictionary — U.S. Code
United States Code
42 U.S.C. § 13368 — as used in this section
The term “coal seam” means any stratum of coal 20 inches or more in thickness, unless a stratum of less thickness is being commercially worked, or can in the judgment of the Secretary of the Interior forseeably 3 be commercially worked and will require protection if wells are being drilled through it.