Pliocene Series

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Lithostratigraphy: Embayment Megagroup
Chronostratigraphy: Cenozoic Erathem >>Tertiary System >>Pliocene Series

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 John C. Frye

Name

Original description

Pliocene Series (Lyell, 1833).

Derivation

The Pliocene Series, translated as "more recent," was so named because the major part of the invertebrate fossils are referable to modern species.

Other names

All of the Pliocene Series deposits were previously called "Lafayette", "Lafayette-type", or "Tertiary" gravel.

History/background

Type section

Type location

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

Extent and thickness

The Pliocene Series is represented in Illinois by the widespread brown chert gravel deposits of southern Illinois-- the Mounds Gravel-- and the similar but scattered deposits in western Illinois-- the Grover Gravel.

Lithology

Core(s)

Photograph(s)

Contacts

Well log characteristics

Fossils

Age and correlation

Both the Mounds and Grover Formations probably contain some deposits reworked during the early Pleistocene that are not readily differentiated from those deposited during the late Tertiary. Consequently, both the Mounds and Grover Formations are assigned a Pliocene-Pleistocene age (Willman and Frye, 1970).

Environments of deposition

Economic importance

Remarks

References

LYELL, CHARLES, 1833, Principles of geology: v. 3, London, p. 52-55, 57-58.
WILLMAN, H. B., and J. C. FRYE, 1970, Pleistocene stratigraphy of Illinois: Illinois State Geological Survey Bulletin 94, 204 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation
1210
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