Remote surface mapping using orthophotos and geologic maps draped over digital elevation models: Application the Sheep Mountain anticline, Wyoming

Remote mapping of surface structures can be conducted by draping digital orthophotos and geologic maps over digital elevation models in geographic information systems. Formational contacts can be mapped by viewing the intersections of these contacts with the topography on a true-to-scale, three-dimensional image. Bedding orientations can be determined from (1) the trends and slopes of dip slopes or (2) best fit planes to multiple points of intersection of a bedding surface with the topography. The methods are tested against mapped formation contacts and bedding attitudes for the Sheep Mountain anticline in the Bighorn basin, Wyoming. Detailed mapping of formation contacts is improved by careful observations of the contacts on three-dimensional images. Interpreted bedding attitudes from slope and multiple-point solutions show strong positive correlations with field measurements. This mapping method provides an efficient and accurate alternative to stereoscopic mapping using aerial photographs and satellite images, particularly for remote and inaccessible areas.