Pg. 197. Crazy Johnson member of Chadron formation. [White River group not used.] Author previously described unit as "Middle Member" of Chadron (Clark, 1937). Underlies Peanut Peak member (new) and overlies Ahearn member (new); both of Chadron. Fossiliferous. Red-orange color. No other descriptive information included. Age is early Oligocene.
Type locality: at standard section of Chadron formation in Big Badlands on south fork of Indian Creek, Pennington Co., SD, from sec. 34, T. 3 S., R. 12 E., to sec. 10, T. 4 S., R. 12 E. Named from prominent butte in southern part of sec. 10, T. 4 S., R. 12 E., locally known as Crazy Johnson Butte. [Same butte also called Peanut Peak, the name given to the overlying Peanut Peak member of Chadron.]

Source: US geologic names lexicon (USGS Bull. 1200, p. 977-978); supplemental information from GNU records (USGS DDS-6; Denver GNULEX).