The Pine Hollow and South Ashland fields located in Pittsburg and Coal Counties, Oklahoma, established a combined reserve exceeding 200 bcf of gas. The Hartshorne Sandstone of early Desmoinesian (Pennsylvanian) age is the producing zone at a depth of 4,000 ft (1,200 m). Gas, probably of biogenic origin, migrated into the reservoir shortly after deposition. Subsequent folding and faulting of the Ashland anticline resulted in repositioning of the gas in a downthrown fault trap. The upthrown anticline portion of the Hartshorne is water-bearing. Moderate well costs and high individual reserves have resulted in excellent economics. Competitive bidding on federal leases has resulted in a high bid exceeding $1 million for one tract in the South Ashland field.