Enion Formation

Lithostratigraphy: Enion Formation
Chronostratigraphy: Cenozoic Erathem >>Quaternary System >>Pleistocene Series

Primary source

Willman, H. B., and John C. Frye, 1970, Pleistocene Stratigraphy of Illinois: Illinois State Geological Survey Bulletin 94, 204 p.

Contributing author(s)

H. B. Willman and John C. Frye

Name

Original description

Enion Formation (Willman and Frye 1970).

Derivation

The Enion Formation is named for Enion, Fulton County.

Type section

Type location

The type section is the Enion Section (table 6), an exposure in a ravine half a mile west of Enion, NW SW SE Sec. 32, T. 4 N., R. 3 E., Fulton County, originally described by Wanless (1929b; 1957, fig. 51, geol. sec. 62). The Enion Formation is also described in the Zion Church Section in Adams County (table 6).

Table 6 -- Stratigraphic Sections (partial)

• 
  Cottonwood School Section (cont.) and Enion Section
• 
  Enion Section (cont.), Farm Creek Section, and Flat Rock Section
• 
  Wedron Section (cont.) and Zion Church Section
• 
  Zion Church Section (cont.)

Stratigraphic relationships

The Enion Formation includes the glacial tills, outwash, and intercalated silts occurring below the base of the Banner Formation or the top of the Afton Soil; it overlies bedrock formations or the Grover Gravel.

Extent and thickness

Exposures of the Enion Formation are known in a relatively small number of localities in central western Illinois. In most of these the till is distorted, and the quantity so small that there is no assurance that the till has not been transported. The high-level outwash gravels of Jo Daviess County (Willman and Frye, 1969) are also included within the formation.

Age and correlation

The Enion Formation is Nebraskan in age. Deposits that might possibly be assigned to the Enion Formation have been described in other areas in Illinois, but the correlations at present are considered questionable and most of the deposits are included in the Banner Formation. These include the drift called Nebraskan (?) in De Witt, McLean, and Livingston Counties (Horberg, 1953) and in Vermilion County (Eveland, 1952). Later examination of an exposure thought to include till of Nebraskan age near Winchester, Scott County (Bell and Leighton, 1929), indicated that the lower till was Kansan rather than Nebraskan (G. E. Ekblaw, personal communication). Gravel resting on bedrock and overlain by the Banner Formation in Fulton and adjacent counties (Wanless, 1957) contains a few igneous pebbles and may be of the same age as the Enion, but it is dominantly chert gravel and is included in the Grover Gravel.

Environments of deposition

It was deposited by glaciers that advanced from the Keewatin center across Minnesota and Iowa and invaded western and northwestern Illinois (fig. 5).

• 
  Fig. 5 -- Sequence of glaciations and interglacial drainage in Illinois.

References

BELL, A. H., and M. M. LEIGHTON, 1929, Nebraskan, Kansan, and Illinoian tills near Winchester, Illinois: Geological Society of America Bulletin, v. 40, no. 2, p. 481-489.
EVELAND, H. E., 1952, Pleistocene geology of the Danville region: Illinois State Geological Survey Report of Investigations 159, 32 p.
HORBERG, C. L., 1953, Pleistocene deposits below the Wisconsin drift in northeastern Illinois: Illinois State Geological Survey Report of Investigation 165, 61 p.
WANLESS, H. R., 1929b, Nebraskan till in Fulton County, Illinois: Illinois Academy of Science Transactions (1928), v. 21, p. 273-282.
WANLESS, H. R., 1957, Geology and mineral resources of the Beardstown, Glasford, Havana, and Vermont Quadrangles: Illinois State Geological Survey Bulletin 82, 233 p.
WILLMAN, H. B., and J. C. FRYE, 1969, Highlevel glacial outwash in the Driftless Area of northwestern Illinois: Illinois State Geological Survey Circular 440, 23 p.

ISGS Codes

ISGS Code and Symbol

Stratigraphic Code	Geo Unit Designation
1160	--