Historical:Meadow Loess Member
H. B. Willman and John C. Frye
The Meadow Loess Member of the Roxana Silt is named for Meadow Heights, a northeastern section of Collinsville, Madison County.
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 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.
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.
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).
Age and correlation
The Meadow Loess occurs late in the Altonian Substage of the Wisconsinan Stage.
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.
|Stratigraphic Code||Geo Unit Designation|