Sterling Till Member

Lithostratigraphy: Glasford Formation >>Sterling Till Member
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

The Sterling Till Member of the Glasford Formation was informally named the Sterling till (Frye et al., 1969, p. 25). It is herein formally named a member (Willman and Frye, 1970).

Derivation

The Sterling Till Member was named for Sterling, Whiteside County.

Other names

History/background

Type section

Type location

The type section is the Emerson Quarry Section (Frye et al., 1969, p. 34) 2 miles west of Sterling, SE NW SE Sec. 13, T. 21 N., R. 6 E.

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

It is the uppermost till member of the Glasford in the region north of the Green River Lobe and is similar in clay mineral composition to the Radnor Till Member, which occupies the same stratigraphic position south of the Green River Lobe.

The upper boundary of the member is the top of the Sangamon Soil, or, locally, the base of the accretion-gley of the Berry Clay Member (e.g., Red Birch School, Coleta Sections, table 7). It is overlain in some places by the Winnebago Formation, the Robein Silt, the Wedron Formation, or the Peoria Loess, and it overlies the Ogle Till Member or older units.

Table 7 -- Described Stratigraphic Sections Previously Published (414 sections from 78 counties are arranged alphabetically, with citation to publication source).

Extent and thickness

The Sterling Member is as much as 40 feet thick in the vicinity of Sterling, but it generally is thinner. The geographic extent of the Sterling Till Member is shown in figure 6.

Fig. 6 -- Areal distribution of the dominantly till formations and members of Illinois.

Lithology

It has an extremely high illite content. Its typical composition is given in table 2.

Table 2 -- Typical Compositions of Glacial Till Units.

Core(s)

Photograph(s)

Contacts

Well log characteristics

Fossils

Age and correlation

The Sterling Till Member is classed within the Jubileean Substage of the Illinoian Stage.

Environments of deposition

Economic importance

Remarks

References

FRYE, J. C., H. D. GLASS, J. P. KEMPTON, and H. B. WILLMAN, 1969, Glacial tills of northwestern Illinois: Illinois State Geological Survey Circular 437, 47 p.

ISGS Codes

Stratigraphic Code	Geo Unit Designation
0840	g-rs