Electrical accessory curves have been used to map the Mesaverde, Lance-Meeteetse, Fort Union, and Willwood Formations in the Bighorn basin of Wyoming. These subsurface mapping units have been correlated to mapped outcrops on the flank of the basin. Recent authors have concluded that the basin started to subside during upper Lance deposition; however, I conclude that most subsidence along the axis of the basin was in late Paleocene and Eocene times (upper Fort Union and Willwood).
Electrical accessory curves also were used to map the Mesaverde, Wasatch, Green River, Uinta, and Duchesne River Formations in the Uinta basin of Utah. These subsurface formations have been correlated to mapped outcrops on the south flank of the basin. Thickening of the Uinta and Duchesne River Formations into the basin indicates that the main subsidence along the axis of the basin was in late Eocene time.