Radnor Till Member

Lithostratigraphy: Glasford Formation >>Radnor 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

Radnor Till Member, Glasford Formation (William and Frye 1970).

Derivation

The Radnor Till Member of the Glasford Formation is named for Radnor Township, Peoria County.

Type section

Type location

The Radnor Till is described from roadcut exposures in the Jubilee College Section (table 6), SW SW SW Sec. 7, T. 10 N., R. 7 E. It is also described in the Farm Creek, Tindall School, and Toulon 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.

Enion Section (cont.), Farm Creek Section, and Flat Rock Section Flat Rock Section (cont.), Gale Section, and Jubilee College 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 Toulon Section (cont.), Washington Grove Section, and Wedron Section

Stratigraphic relationships

In the type section the Radnor Till is bounded at the top by the top of the Sangamon Soil. It is overlain by Roxana Silt and it rests on the Toulon Member. The Radnor Till Member may be a stratigraphic equivalent of the Sterling Till Member of northern Illinois but is geographically separated from it by the Green River Lobe.

Extent and thickness

Its geographic distribution is shown in figure 6 and its spatial relations are shown diagrammatically in figure 7.

Fig. 6 -- Areal distribution of the dominantly till formations and members of Illinois. Fig. 7 -- Diagrammatic cross section showing the relations of formations and members of Illinoian age in western Illinois.

Lithology

The Radnor Till is gray, compact, silty, and high in illite content. Its matrix grain size and composition of clay minerals are given in tables 2 and 5, and its heavy mineral analyses are summarized in table 4.

Table 2 -- Typical Compositions of Glacial Till Units. Table 4 -- Averages of Analyses of Selected Heavy and Light Minerals (Analyses of size fraction 0.062-0.250 mm). (From Frye, Glass, and Willman, 1962; Frye, Willman, and Glass, 1964; Willman, Glass, and Frye, 1963).

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

It is in the Jubileean Substage of the Illinoian Stage and was deposited by the Lake Michigan Lobe.

ISGS Codes

Stratigraphic Code	Geo Unit Designation
0830	g-rs