Gunn Member

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Lithostratigraphy: Potsdam Sandstone Megagroup >>Mt. Simon Sandstone >>Gunn Member
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

The Gunn Member of the Mt. Simon Sandstone (Templeton, 1950, p. 155).

Derivation

Named for Gunn School, De Kalb County.

Other names

History/background

Type section

Type location

The type section of the Gunn Member of the Mt. Simon Sandstone is located 2.75 miles southeast of Gunn School, De Kalb County. The member is 1648-1880 feet deep (sample set 1466) in the same boring as the Lacey Member.

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

The Gunn Member overlies the Lacey Member of the Mt. Simon Sandstone.

Extent and thickness

The Gunn Member is 130-150 feet thick in the Chicago area, but elsewhere it is 71-260 feet thick.

Lithology

It is a relatively fine-grained member, but the sand ranges from fine to medium grained. A few thin conglomeratic beds are present in some areas.

Core(s)

Photograph(s)

Contacts

Well log characteristics

Fossils

Age and correlation

Environments of deposition

Economic importance

Remarks

References

TEMPLETON, J. S., 1950, Mt. Simon Sandstone in northern Illinois: Illinois Academy of Science Transactions, v. 43, p. 151-159.

ISGS Codes

Stratigraphic Code Geo Unit Designation
8830
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