Meadow Loess Member

Lithostratigraphy: Roxana Silt >>Meadow Loess 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

Meadow Loess Member (Willman and Frye 1970).

Derivation

The Meadow Loess Member of the Roxana Silt is named for Meadow Heights, a northeastern section of Collinsville, Madison County.

Type section

Type location

Its type section is the Pleasant Grove School Section (table 6) three quarters of a mile west of Meadow Heights, SW NE SE Sec. 20, T. 3 N., R. 8 W.

Table 6 -- Stratigraphic Sections (partial)
The following stratigraphic sections describe exposures in Illinois and illustrate many aspects of Pleistocene stratigraphy, including type localities and analytical sample data.

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  Pleasant Grove School Section

Stratigraphic relationships

It is the uppermost member of the Roxana Silt, and in previous Illinois literature was called zones II, III, and IV of the Roxana Silt (Frye and Willman, 1960, 1963b; Frye, Glass, and Willman, 1962).

This member forms the major part of the Roxana Silt. It rests on the Pleasant Grove Soil developed in McDonough Loess and is terminated upward by the top of the Farmdale Soil or by the Robein Silt, Morton Loess, or Peoria Loess.

Lithology

The Meadow Loess is a uniform silt and the three zones are based largely on color, pinkish tan in the lower and upper parts and gray to gray-tan loess in the middle. Although the zones have gradational contacts, they are distinct in the area of thick Roxana Loess from Havana, Mason County, to Gale, Alexander County, more than 250 miles. They become less distinct as the loess thins back from the bluffs and are rarely recognizable more than 15 miles from the bluffs. The mineral composition of the loess is given in tables 4 and 5, its spatial relations are shown diagrammatically in figure 8, and radiocarbon dates are listed in table 1. Its character is described in many of the stratigraphic sections in this report (table 6).

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  Table 1 -- Selected Stratigraphically Significant Radiocarbon Dates From Illinois (94 dates from 30 counties).
• 
  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).
• 
  Fig. 8 -- Diagrammatic cross section showing the relations of formations and members of Wisconsinan age in northern and western Illinois.

Selected analyses from stratigraphic sections (X-ray analyses by Illinois State Geological Survey).

• 
  Table 5 -- Continued.

Age and correlation

The Meadow Loess occurs late in the Altonian Substage of the Wisconsinan Stage.

References

FRYE, J. C, H. D. GLASS, and H. B. WILLMAN, 1962, Stratigraphy and mineralogy of the Wisconsinan loesses of Illinois: Illinois State Geological Survey Circular 334, 55 p.
FRYE, J. C, and H. B. WILLMAN, 1960, Classification of the Wisconsinan Stage in the Lake Michigan glacial lobe: Illinois State Geological Survey Circular 285, 16 p.
FRYE, J. C, and H. B. WILLMAN, 1963b, Loess stratigraphy, Wisconsinan classification and accretion-gleys in central western Illinois: Midwestern Section Friends of the Pleistocene, 14th Annual Meeting, Illinois State Geological Survey Guidebook Series 5, 37 p.

ISGS Codes

ISGS Code and Symbol

Stratigraphic Code	Geo Unit Designation
0650	--