Historical:Duncan Mills Member

Lithostratigraphy: Glasford Formation >>Duncan Mills Member
Chronostratigraphy: Cenozoic Erathem >>Quaternary System >>Pleistocene Series

Authors

H. B. Willman and John C. Frye

Name origin

The Duncan Mills Member of the Glasford Formation is named for Duncan Mills, Fulton County.

Other names

The Duncan Mills Member has previously been called Jacksonville-Buffalo Hart deposits (Wanless, 1957).

Type section

The type section is from exposures in the Enion Section (table 6) 4 miles south of Duncan Mills, NW SW SE Sec. 32, T. 4 N., R. 3 E. It is also described in the Cottonwood School, Lewistown, and Tindall School Sections (table 6).

Table 6 -- Stratigraphic Sections (partial) The following 21 stratigraphic sections describe exposures in Illinois and illustrate many of the aspects of Pleistocene stratigraphy. These sections contain the type localities for 21 rock-stratigraphic units, 4 soil-stratigraphic units, and 3 time-stratigraphic units and include paratypes for several other units. The sample numbers preceded by "P" are the numbers used in the Illinois State Geological Survey collections. Analytical data on many of these samples are on file at the Survey. The sections are arrange alphabetically by name.

Cottonwood School Section (cont.) and Enion Section Enion Section (cont.), Farm Creek Section, and Flat Rock Section Jubilee College Section (cont.), Lewistown Section, and Malden South Section Pulleys Mill Section, Rochester Section, and Tindall School Section Tindall School Section (cont.) and Toulon Section

Stratigraphic relationships

It is bounded by the Hulick Till Member above and the Kellerville Till Member below, and is recognized as a member only when it is contained between these two bounding till units.

Extent and thickness

The Duncan Mills Member is as much as 30 feet thick.

Lithology

In the type section the Duncan Mills Member consists of glacially derived sand, and sand and gravel with some silt, generally deeply weathered. Clay mineral composition is given in table 5.

Table 5 -- Selected Analyses from Stratigraphic Sections Described in Table 6 (X-ray analyses by H. D. Glass, Illinois State Geological Survey). Table 5 -- Continued.

Age and correlation

The Duncan Mills Member locally contains deposits in both the Monican and Liman Substages of the Illinoian Stage. It contains outwash of the retreating Kellerville glacier and deposits of the advancing Hulick glacier.

References

WANLESS, H. R., 1957, Geology and mineral resources of the Beardstown, Glasford, Havana, and Vermont Quadrangles: Illinois Geological Survey Bulletin 82, 233p.

ISGS Codes

Stratigraphic Code	Geo Unit Designation
0930	--