Year: 2018
Type: article
Abstract: The Shelbyville Moraine is one of the best known end moraines in the central United States.Recent excavations for a new dam in the moraine at Shelbyville, Illi- nois, have shown that only one Wisconsinan till is present at the site and that its base lies at the same general elevation as the Illinoian drift plain to the south.At the type locality, therefore, the Shelbyville is a terminal end moraine of the Wisconsinan ice sheet.A radiocarbon date of 20,000 ± 200 years B. P. (ISGS 26) obtainedfrom silty peat immediately below the Shelbyville Drift represents the approximate age of the glacial advance to the position of the moraine.Morton Loess, RobeinSilt, and Roxana Silt, as well as the Berry Glay and Vandalia Till Members of the Glas- ford Formation, are exposed below the Shelbyville Drift.A radiocarbon date of 21,400 ± 1,000 years B. P. (ISGS 46) from organic material in the upper 12 inches of the Ber- ry Clay Member indicates that from late Illinoian time to early Woodfordian time accretion-gley accumulated locally in this area and that loess deposited during this period was incorporated into the Berry Clay.Radiocarbon dates of 21, 300+500 years B. P. (ISGS 32) and 20, 000+200 years B. P. (ISGS 26), respectively, from the base and top of Robein Silt indicate that at Shelbyville the Robein is Woodfordian in age and that it accumulated contemporaneously with Morton Loess.
Author: W. Hilton Johnson
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2289753605