Ancell Group

Lithostratigraphy: Ottawa Limestone Megagroup >>Ancell Group
Chronostratigraphy: Paleozoic Erathem >>Ordovician System >>Champlainian Series >>Blackriveran Stage
Allostratigraphy: Tippecanoe 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)

H. B. Willman and T. C. Buschbach

Name

Original description

Ancell Group (Templeton and Willman, 1963, p. 29).

Derivation

Named for Ancell in southeastern Missouri.

Type section

Type location

The type section of the Ancell Group is a composite of several sections in the bluffs north of Ancell, between Dutchtown and Rock Levee, Missouri.

Stratigraphic relationships

North of a line roughly extending from Chicago to Quincy, the Ancell strata above the St. Peter Sandstone consist of the members of the Glenwood Formation, but south of that line they consist of the Joachim and Dutchtown Formations (fig. O-15). The Glenwood, Dutchtown, and Joachim Formations all appear to have a facies relation to the upper part (Starved Rock Member) of the St. Peter Sandstone (fig. O-16).

Fig. O-15 -- Columnar section of the Ancell Group (after Templeton and Willman, 1963). Fig. O-16 -- Diagrammatic cross section of the Ancell Group (after Templeton and Willman, 1963).

Extent and thickness

As the Everton is present only in southern Illinois, the Ancell Group overlies Canadian strata in most of the state or Cambrian strata locally. Ancell strata underlie most of Illinois, and they vary in thickness from a few feet to as much as 900 feet.

Lithology

The Ancell Group consists of the sandstone and the argillaceous and sandy limestone and dolomite formations that overlie the Everton Dolomite and underlie the Platteville Group, which is relatively pure limestone. The St. Peter Sandstone is the basal formation in the group.

References

TEMPLETON, J. S., and H. B. WILLMAN, 1963, Champlainian Series (Middle Ordovician) in Illinois: Illinois State Geological Survey Bulletin 89, 260 p.

ISGS Codes

Stratigraphic Code	Geo Unit Designation
8160	Oa