The thermal water deposits of the Dubois, Wyoming, area occur in 5 groups in the forms of domes, cliffs, flows, extinct geyser orifices, and natural bridges. The natural bridge group is not discussed. Two of the groups are along principal streams which flow perpendicular to outcrop strike; the remaining 2 groups parallel the strike of the outcrops. The deposits, which are principally calcium carbonate, occur on strata ranging in age from Mississippian to Permian; the undoubted sources of the mineral enrichment were the underlying Paleozoic limestones. All of the thermal water deposits are underlain by a travertine cemented conglomerate which seemingly dates them as post-Pleistocene, but the correct age is dependent on the age of warm Spring Canyon. The mineral-bearing waters reached the surface by travelling along bedding planes and possibly along faults.