"U.S." . . . "Green River formation, in the northern part of the Piceance Creek Basin, Rio Blanco County, Colorado"@en . . "Maps"@en . . . "Mahogany zone, Green River formation, in the northern part of the Piceance Creek Basin, Rio Blanco County, Colorado"@en . . "Piceance Creek Basin, Rio Blanco County, Colorado"@en . "Structure contours and overburden on the top of the Mahogany zone, Green River formation, in the northern part of the Piceance Creek Basin, Rio Blanco County, Colorado"@en . . . . . .