Historical:Lierle Clay Member
H. B. Willman and John C. Frye
The Lierle Clay Member of the Banner Formation is named for Lierle Creek, Adams County, Illinois.
The type section is in roadcut exposures, the Lierle Creek Section (Frye and Willman, 1965a, bed 5, p. 107), in the SE corner SW Sec. 33, T. 1 S., R. 6 W. It is also well exposed 5 miles east in roadcuts, SW SE SE Sec. 32, T. 1 S., R. 5 W., Adams County. The member is exposed at many places in the area where Kansan age drift is the surface drift (pl. 2).
It is bounded at the base by till of the Banner Formation, and at the top by Loveland or Petersburg Silt, the Glasford Formation, or younger deposits.
Extent and thickness
It rarely exceeds 10 feet thick.
The Lierle Clay Member consists of the accretion-gley that locally overlies the tills of the Banner Formation. In this report it is described in the Zion Church Section (table 6), and a clay mineral analysis is given in table 5. Analytical data on the accretion-gley have been published (Willman, Glass, and Frye, 1966). It is a gray, massive, montmorillonitic, leached clay, with some silt and sand and a few dispersed small pebbles.
|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.
Age and correlation
In age, the Lierle Clay Member is Yarmouthian and locally also late Kansan.
Environments of deposition
It is the product of slow accumulation of sediments, moved by sheetwash and possibly also by wind action, in poorly drained situations on the surface after the retreat of the Kansan glaciers. The sediments accumulated in a soil-forming environment that was intermittently wet, and the entire deposit is considered an accreted soil.
FRYE, J. C., and H. B. WILLMAN, 1965a, [Illinois part of] Guidebook for field conference C—Upper Mississippi Valley (R. P. Goldthwait [organizer]; C. B. Schultz and H. T. U. Smith [eds.]): International Association of Quaternary Research 7th Congress, Nebraska Academy of Science, p.81-110; Illinois State Geological Survey Reprint 1966-B (supplemental data, J. P. Kempton and H. D. Glass, p. C-S1-C-S11), 41 p.
WILLMAN, H. B., H. D. GLASS, and J. C. FRYE, 1966, Mineralogy of glacial tills and their weathering profiles in Illinois. Part II—Weathering profiles: Illinois State Geological Survey Circular 400, 76 p.
|Stratigraphic Code||Geo Unit Designation|