Pg. 110; and 1905, USGS Prof. Paper 36, p. 28-30. Spergen Hill limestone. Generally massive layers of oolitic limestone, of light- or dark-gray, buff, or drab color, with interbedded thinner layers of various kinds of limestone and occasionally thin seams of yellowish shale, occurring in Indiana, Illinois, western Kentucky, and eastern Missouri. Thickness few feet to 125 feet. Included in St. Louis limestone of previous reports. Overlain by St. Louis limestone [restricted] and underlain by Warsaw formation. Included in Meramec group.
[Named from Spergen Hill, near railroad station of Harristown, a few mi. southeast of Salem, Washington Co., IN.]

Source: US geologic names lexicon (USGS Bull. 896, p. 2039).

Name Spergen adopted instead of Bedford Limestone (preoccupied) and Salem Limestone (Cumings, 1901), because of long-established use of terms "Spergen Hill fauna" and "Spergen fauna", to designate fauna contained in this formation, and because the name had acquired a formational significance long before Salem Limestone was introduced, e.g.: S.S. Lyon, 1860 (St. Louis Acad. Sci. Trans., v. 1, p. 619), described strat. horizon in Kentucky which he stated to be equivalent to "Spergen Hill" beds of Washington County, Indiana; C.E. Siebenthal, 1897 (Indiana Dept. Geol. And Nat. Res. 21st Ann. Rept., p. 298), stated that the Bedford oolitic limestone had also been called Spergen Hill Limestone by other writers; S. Weller, 1898 (Jour. Geol., v. 6, p. 313), stated: "One of the best known of the St. Louis Limestone faunas is that of the Spergen Hill beds in Indiana"; H.S. Williams, 1900 (Arkansas Geol. Surv., v. 5, p. 348), stated: "The age of the Spring Creek Limestone is about equivalent to the Warsaw, St. Louis, or Spergen Hill formations." Salem Limestone, however, is name used by Indiana and Illinois Geol. Surveys. The Spergen is middle formation of Meramec Group. It is overlain by Mitchell Limestone in Indiana and by St. Louis Limestone in Illinois, Missouri, Iowa, and western Kentucky; underlain by Warsaw Shale in Illinois, Iowa, and eastern Missouri, and by Warsaw (†Harrodsburg) Limestone in Indiana and western Kentucky. It is opinion of C. Butts (Kentucky Geol. Survey, ser. 6, v. 7, p. 119-120, 1922) that Spergen Limestone of Indiana is only a local lithologic facies of Warsaw Limestone, but most geologists consider it a distinct geologic unit of equal rank with Warsaw, St. Louis, and other formations. W.H. Twenhofel, however (Kentucky Geol. Survey, ser. 6, v. 37, 1931), inclined to Butt's view.

Source: US geologic names lexicon (USGS Bull. 896, p. 2039-2040).

Extended into the subsurface of Baca County, Colorado, in the Anadarko basin, east of the Las Animas arch. Overlies Warsaw limestone and underlies St. Louis limestone. Age is Late Mississippian (Meramecian). Report includes correlation chart.

Source: Modified from GNU records (USGS DDS-6; Denver GNULEX).