Pre-Wisconsin Glaciation of Central North America

Work Group on Geospatial Analysis of Glaciated Environments (GAGE)
INQUA Commission on Glaciation

GAGE or INQUA

The work group on Geospatial Analysis of Glaciated Environments (GAGE) has undertaken a project to compile a GIS database and produce maps on the glaciated region south of the Wisconsin ice limit, in the central United States. This project is conducted in cooperation with a sister work group on Extent and Chronology of Glaciation (worldwide). Both groups function within the INQUA Commission on Glaciation.

Background

The Wisconsin and Illinoian glacial stages are still accepted and widely used for glacial stratigraphy and correlation in North America and elsewhere. However, the Kansan and Nebraskan are no longer considered valid glacial stages in light of much evidence for more complicated pre-Illinoian glaciation of the central United States (Richmond & Fullerton 1986). Hallberg's (1986) early and middle Pleistocene stratigraphy for Iowa and Nebraska now serves as the standard for the region. More recently, Aber (1991) proposed a revision for glaciation in northeastern Kansas. This phase of ice-sheet advance is now called the Independence Glaciation, dated 600,000 to 700,000 years ago. A minimum age for pre-Illinoian glaciation of the Missouri basin has been provided recently by radiometric dating of glacial pavement on Sioux Quartzite bedrock in southwestern Minnesota, 575±57 thousand years ago.

See cosmogenic date.

The Glacial map of the United States east of the Rocky Mountains (Flint et al. 1959) displays the distribution of glacial deposits and related features in the central United States, as they were known and interpreted in the 1950s. Little attempt has been made during the past four decades to revise or update this map in spite of much new information concerning glaciations of this classic region. This project represents application of new methods--geographic information systems (GIS)--for compiling and producing a synthesis map of glacial features in the central North America.

Map Status

GIS data entry is completed for the region from Illinois to North Dakota: latitude 37-49°N, longitude 87-104°W. Glacial features have been derived from various published and unpublished sources-see source references. The glacial features have been combined with digital line graphs (basic geography) and digital elevation models (basic topography). A classification and ID code system has been developed for glacial phenomena. GIS data entry, editing, and map production took place at the GeoSpatial Analysis Laboratory, Emporia State University, Kansas, USA.

The ultimate goal is to publish comprehensive maps and reports on pre-Wisconsin glacial phenomena in the central United States. Many individuals have sent information, volunteered to help compile data, or reviewed map products--see map contributors.

Overview map north-central United States. Clickable for nine detailed regional maps.

Abstract of Pre-Illinoian glacial geomorphology and dynamics in the central United States, west of the Mississippi (Aber 1999).

For further information about this project, contact James S. Aber, aberjame@emporia.edu.

GAGE homepage.

References

Last update: 6 Jan. 2000.