 He discovered a set of copper plates, the Etowah plates, several of which are the famous copper eagle dancer plates, which were later named the Rogan plates (the plates are now Catalogue Nos.A91117 and A91113 in the collections of the Department of Anthropology, National Museum of Natural History, Smithsonian Institution).Rogan tested seven other archaeological sites in Georgia in Bartow, White, Habersham, Forsyth, Rabun, Elbert, and McIntosh counties.