 While surveying for sites in northeast Thailand with Wilhelm Solheim between 1963-1964, Gorman also discovered the site of Non Nok Tha.Gorman excavated Spirit Cave (Tham Phii Man) once in 1966 for his dissertation research, and again in 1971.He also excavated Banyan Valley Cave (Tham Sai) in 1972 and Steep Cliff Cave (Tham Phaa Can) in 1973.