This study deals with imperfectly and poorly drained soils generally considered to have developed under prairie from a parent material consisting of a sandy-silt mantle overlying Iowan glacial loam till. Three Floyd profiles, two profiles of the proposed Tripoli series (Floyd, poorly drained variant), and one Clyde profile were studied in the field and in the laboratory. Results indicate that the Tripoli soils should be separated from the Floyd and mapped as a separate series. The present concepts of the Floyd series as a minimal Brunizem and the Tripoli as a minimal Wiesenboden are substantiated by field studies and laboratory data