Okla. Stat. tit. 52, § 52-306: Workable coal beds or seams defined

All coal beds or seams thirty (30) inches to thirty-six (36)

inches in thickness, less than one thousand (1,000) feet below the

surface, and all coal beds or seams more than thirty-six (36) inches

in thickness, less than one thousand five hundred (1,500) feet below

the surface, shall be deemed as workable.

Added by 1955, p. 255, § 2.