Geologic history of natural coalbed fires, Powder River basin, .
WEBJul 12, 2004 · In the western United States, coal beds have burned naturally in several geologic basins in the states of Wyoming, Montana, North Dakota, Colorado, Utah, New Mexico, and Arizona Sigsby, 1966, Hoffman, 1996. The most extensive burning has been in the Powder River basin (PRB) of northeast Wyoming and southeast Montana Rogers, .