Historical:Radnor Till Member

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Pleistocene stratigraphy of Illinois
Series Bulletin 94
Author H. B. Willman and John C. Frye
Date 1970
Link Web page
PDF PDF file

Lithostratigraphy: Glasford Formation >>Radnor Till Member
Chronostratigraphy: Cenozoic Erathem >>Quaternary System >>Pleistocene Series


H. B. Willman and John C. Frye

Name origin

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

Type section

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.

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.


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.

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