Peyton Colluvium

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Lithostratigraphy: Peyton Colluvium
Chronostratigraphy: Cenozoic Erathem >>Quaternary System >>Holocene Series

Primary source

Willman, H. B., and John C. Frye, 1970, Pleistocene Stratigraphy of Illinois: Illinois State Geological Survey Bulletin 94, 204 p.

Contributing author(s)

H. B. Willman and John C. Frye

Name

Original description

Peyton Colluvium (Willman and Frye 1970).

Derivation

The Peyton Colluvium is named for Peyton Creek, which crosses an area of the formation that is mapped as slopewash and alluvial fans (Wanless, 1957) at the base of the Illinois Valley bluffs 1.5 miles southwest of Glasford, NW NE Sec. 32, T. 7 N., R. 6 E., Peoria County. It is here classified as a formation.

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Lithology

It includes the widely distributed but narrow belts of poorly sorted debris that accumulated at the base of steep slopes, largely by creep and slopewash. The numerous small alluvial fans and cones that occur at nearly every gully and grade into slopewash deposits are included in the formation. The material is dominantly a pebbly silt, but its composition depends on the material in the bluffs above. Along loess-mantled bluffs it appears to grade upward into loess by decrease in the abundance of pebbles. At its lower margin the colluvium grades or interfingers into the stream or river alluvium, but the Peyton Colluvium is separated from the Cahokia Alluvium by vertical cutoff.

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References

WANLESS, H. R., 1957, Geology and mineral resources of the Beardstown, Glasford, Havana, and Vermont Quadrangles: Illinois State Geological Survey Bulletin 82, 233 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation
0090
py