Rivoli Member

Lithostratigraphy: Ottawa Limestone Megagroup >>Galena Group >>Kimmswick Subgroup >>Dunleith Formation >>Rivoli Member
Chronostratigraphy: Paleozoic Erathem >>Ordovician System >>Champlainian Series >>Trentonian 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

The Rivoli Member of the Dunleith Formation (Templeton and Willman, 1963, p. 122).

Derivation

Named for Rivoli Street in East Dubuque, Jo Daviess County, near the type section.

Type section

Type location

The type section of the Rivoli Member is part of the Dunleith Formation type section (in an exposure in the Mississippi River bluffs on the north side of East Dubuque (SE 19, 29N-2W))(fig. O-2B), where the Rivoli Member is 19 feet thick.

Fig. O-2B -- Type section of Dunleith Formation showing the Mortime (Mo), Rivoli (Ri), Sherwood (Sh), Wall (Wa) and Wyota (Wy) Members overlain by the Sinsinawa Member (Si) of the Wise Lake Formation at East Dubuque, Jo Daviess County (Templeton and Willman, 1963, geolo. sec 28, p. 238).

Stratigraphic relationships

The Rivoli Member of the Dunleith Formation overlies the Mortimer Member.

Extent and thickness

The Rivoli Member thins eastward from the type section and is 13 feet thick in central northern Illinois.

Lithology

The Rivoli Member is the most argillaceous of the Dunleith members. The upper 5 feet is a persistent argillaceous zone that is very cherty in the type section. The lower 5-6 feet contains bands of large chert nodules. Corrosion surfaces are strongly developed in the Rivoli. Thin lenses of bentonite are locally present at or near the top and probably occur at other horizons, especially along sharp reentrants.

Fossils

Receptaculites oweni is abundant in upper Rivoli strata and the overlying Sherwood Member- the Middle Receptaculites Zone.

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
7670	--