Galesville Sandstone

Lithostratigraphy: Knox Dolomite Megagroup >>Galesville Sandstone
Chronostratigraphy: Paleozoic Erathem >>Cambrian System >>Croixan Series >>Dresbachian Stage
Allostratigraphy: Sauk Sequence

Primary source

Willman, H. B., Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, and Jack A. Simon, 1975, Handbook of Illinois Stratigraphy: Illinois State Geological Survey Bulletin 95, 261 p.

Contributing author(s)

T. C. Buschbach

Name

Original description

Galesville Sandstone (Trowbridge and Atwater, 1934, p. 43).

Derivation

Named for Galesville, Trempealeau County, Wisconsin.

History/background

In earlier reports Galesville and Ironton Sandstones were called the Dresbach Sandstone.

Type section

Type location

The type section of the Galesville Sandstone is in an exposure on Beaver Creek near Galesville, Trempealeau County, Wisconsin. The section exposes poorly sorted, fossiliferous sandstone of the Ironton Formation overlying 88 feet of the Galesville Sandstone, which in turn lies on fossiliferous sandstoneand shale of the Eau Claire Formation.

Extent and thickness

The Galesville occurs throughout the northern half of Illinois but is not exposed. It is commonly 40-100 feet thick. At its southern margin, the Galesville grades laterally through a zone of dolomitic sandstone about 50 miles wide to nonsandy dolomite of the Knox Megagroup.

Lithology

In many borings in Illinois the Galesville is not easily distinguished from the overlying Ironton Sandstone, and their combined thickness is shown in figure Є-10. The name "Galesville" is applied as far south as the sandy zone can be identified, at which place the formation is terminated by vertical cut-off. The Galesville Sandstone consists of white to light buff, clean to locally silty, fine-grained, moderately well sorted, friable, and generally nondolomitic sandstone (Buschbach, 1964). Locally, light buff to pink dolomite is a cementing material. The Galesville and the overlying Ironton Sandstone form an important aquifer in northern Illinois.

Fig. Є-10 -- Thickness of the Ironton and Galesville Sandstones.

Contacts

The Galesville appears to be conformable with both the overlying and underlying formations.

Age and correlation

The Galesville Sandstone is also recognized in Iowa, Minnesota, Michigan, and Indiana. It is not traced directly to the Missouri outcrop region, but it probably is equivalent to the upper carbonate beds of the Bonneterre Formation.

Environments of deposition

From a petrographic study and analysis of sedimentary structures, Emrich (1966) concluded that the Galesville and Ironton Sandstones were derived from pre-existing sedimentary rocks north of Illinois and were deposited on a broad, shallow shelf.

References

BUSCHBACH, T. C., 1964, Cambrian and Ordovician strata of northeastern Illinois: Illinois State Geological Survey Report of Investigations 218, 90 p.
EMRICH, G. H., 1966, Ironton and Galesville (Cambrian) Sandstones in Illinois and adjacent areas: Illinois State Geological Survey Circular 403, 55 p.
TROWBRIDGE, A. C., and G. I. ATWATER, 1934, Stratigraphic problems in the upper Mississippi Valley: Geological Society of America Bulletin, v. 45, p. 21-80.

ISGS Codes

Stratigraphic Code	Geo Unit Designation
8750	ig