Exposed strata of Ordovician through Early Permian age in the Samaria Mountain area comprise the following formations: Swan Peak quartzite, Fish Haven-Laketown Dolomite sequence, Water Canyon Formation, Jefferson Formation, Humbug Formation, Great Blue Limestone, Manning Canyon Formation, Oquirrh Formation and Phosphoria Formation. The Jefferson Formation is divided into two members: the Samaria Limestone Member (new) and the Hyrum Member. The Lodgepole Limestone has four informal members. Three members are recognized in the Oquirrh Formation: The West Canyon Limestone Member (Morrowan-Atokan), the middle member (Late Pennsylvanian), and the upper member (Early Permian). A major unconformity occurs between the West Canyon and upper members. The middle member is apparently an allochthonous complexly folded and thrust-faulted mass which overlies the upper member.