The Winslow Formation was a geologic formation in Arkansas, now abandoned and replaced by the Atoka Formation, the Hartshorne Formation, and the lower McAlester Formation (previously Spadra Shale). It preserves fossils dating back to the Carboniferous period.
- ^ Adams, G.I.; Ulrich, E.O. (1904). "Zinc and lead deposits of northern Arkansas". U.S. Geological Survey Professional Paper. 24: 29.
- ^ Hendricks, T.A.; Parks, B. (1950). "Geology of the Fort Smith District". U.S. Geological Survey Professional Paper. 221-E.
- ^ Collier, A.J. (1907). "The Arkansas coal field". U.S. Geological Survey Bulletin. 326.
- ^ Purdue, A.H. (1909). Slates of Arkansas. Geological Survey of Arkansas.