Roxana Silt

Lithostratigraphy: Mason Group >>Roxana Silt
Chronostratigraphy: Cenozoic Erathem >>Quaternary System >>Pleistocene Series

Primary source

Hansel, Ardith K., and W. Hilton Johnson, 1996, Wedron and Mason Groups: Lithostratigraphic Reclassification of Deposits of the Wisconsin Episode, Lake Michigan Lobe Area: Illinois State Geological Survey Bulletin 104, 116 p.

Contributing author(s)

Ardith K. Hansel and W. Hilton Johnson

Name

Original description

Roxana silt (Frye and Willman 1960).

Derivation

Roxana, a village in Madison County, southwestern Illinois.

History/background

Frye and Willman (1960) named the Roxana Silt for a succession of distinctive silt units that occur above the Sangamon Geosol and below the Peoria Silt. The unit was later formalized as a formation and subdivided into members. In this revision, the Robein Silt is incorporated as the uppermost unit, the Robein Member, within the Roxana Silt.

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  Figure 9 -- History of the litho-stratigraphic classification of the Mason Group deposits with respect to the Wedron Group deposits: (a) Peoria and Roxana Silts, (b) Henry Formation, and (c) Equality Formation. Vertical lines indicate part of section missing due to erosion.

Type section

Type location

Pleasant Grove School Section in the Mississippi Valley bluff southeast of Roxana; good for lithology and lower contact.

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  Figure 29 -- Loess of the Peoria and Roxana Silts above the Sangamon Geosol developed in the Teneriffe Silt (Illinois Episode) at the Pleasant Grove School Section. The modern soil is developed in the upper part of the Peoria Silt.

Type status

No longer available, has been mined out for fill.

Reference section

Reference location

Arenzville, Athens North Quarry, Bellefontaine Quarry, Cottonwood School, Farm Creek, and Glendale School Sections; all good for lithology and contacts.

Stratigraphic relationships

The Roxana Silt occurs above the Sangamon Geosol and below the Peoria Silt, Henry and Equality Formations, or the Wedron Group. The Farmdale Geosol commonly occurs in the upper part of the unit. Contacts are generally gradational.

Extent and thickness

Widespread across the midcontinent region; thickest along major river valleys such as the Mississippi and Illinois Valleys.

Lithology

Dominantly silt, commonly brownish red when oxidized and gray when saturated. Contains sand and clay in variable proportions and often displays pedogenic features, biopores, and root traces.

Contacts

Lower boundary: contact with Glasford or older formations. Upper boundary: contact with Peoria Silt, Henry and Equality Formations, or Wedron Group.

Age and correlation

Deposited during the Alton Phase of the Athens Subepisode of the Wisconsin Episode.

• 
  Figure 10 -- Geochronological units, chronostratigraphic units and diachronic units in the Lake Michigan Lobe in a transect from south of Peoria, Illinois, to north of the Straits of Mackinac in Michigan (geochronologic and chronostratigraphic units are after Frye et al. 1968, as modified by Follmer et al. 1979, Curry and Follmer 1992, and Evenson et al. 1976; upper part of time-distance diagram and phases of the Michigan Subepisode are after Hansel and Johnson 1992).

Environments of deposition

Primarily loess derived from major river floodplains, with local colluvial contributions and extensive pedogenic modification.

Remarks

Revised unit. Upper boundary locally extended to include materials formerly classified as Robein Silt.

References

BETTIS, E. A., III, HALLBERG, G. R., and KEMMIS, T. J., 1990, Stratigraphy and origin of the loess of the central Mississippi Valley: Geological Society of America Bulletin, v. 102, p. 706–717.
CURRY, B. B., and FOLLMER, L. R., 1992, The last interglacial-glacial transition in Illinois: 123–143 in Clark, P. U., and Lea, P. D., eds., The Last Interglacial-Glacial Transition in North America: Geological Society of America Special Paper 270.
FEHRENBACHER, J. B., et al., 1986, Loess in Illinois: Illinois State Geological Survey Bulletin 100, 128 p.
FRYE, J. C., GLASS, H. D., and WILLMAN, H. B., 1974a, Stratigraphy and mineralogy of Woodfordian loesses of Illinois: Illinois State Geological Survey Circular 427.
FRYE, J. C., GLASS, H. D., and WILLMAN, H. B., 1974b, Woodfordian loesses and their weathering profiles in Illinois: Illinois State Geological Survey Circular.
FRYE, J. C., and WILLMAN, H. B., 1960, Classification of the Wisconsinan Stage in the Lake Michigan glacial lobe: Illinois State Geological Survey Circular 285.
JOHNSON, W. H., and FOLLMER, L. R., 1989, Source and origin of Roxana Silt in Illinois: Geological Society of America Abstracts with Programs.
JOHNSON, W. H., et al., 1972, Stratigraphy of Quaternary deposits in Illinois: Illinois State Geological Survey.
LEIGH, D. S., 1991, Episodic deposition of late Quaternary loess, Mississippi Valley, USA: Quaternary Research, v. 35, p. 52–60.
LEIGH, D. S., 1994, Paleoclimatic implications of sedimentologic and geochemical characteristics of loess deposits: Quaternary Science Reviews.
LEIGH, D. S., and KNOX, J. C., 1993, Stratigraphy and sedimentology of late Quaternary loess in the Upper Mississippi Valley: Geological Society of America Bulletin.
LEIGH, D. S., and KNOX, J. C., 1994, Loess stratigraphy and climatic interpretations: Quaternary International.
LEIGHTON, M. M., 1931, The Peorian loess and the classification of the glacial stages of the Pleistocene: Journal of Geology.
LEIGHTON, M. M., 1933, The naming of the subdivisions of the Wisconsin glacial stage: Science.
LEIGHTON, M. M., and WILLMAN, H. B., 1950, Loess formations of the Mississippi Valley: Journal of Geology.
McKAY, E. D., 1979b, Stratigraphy of Wisconsinan loess in Illinois: Illinois State Geological Survey Guidebook.
NORTON, D. K., et al., 1988, Characteristics of late Quaternary loess deposits: Geological Society of America.
REED, E. C., and DREESZEN, V. H., 1965, Late Wisconsin history of the central Great Plains: Geological Society of America Special Paper.
RUHE, R. V., and OLSON, C. G., 1978, Loess stratigraphy and soil development: Soil Science Society of America Journal.
SMITH, G. D., 1942, Illinois loess: Journal of Geology.
WASCHER, H. L., et al., 1948, Loess deposits of Illinois: Illinois Agricultural Experiment Station.
WAYNE, W. J., 1963, Pleistocene formations in Indiana: Indiana Geological Survey Bulletin.
WILLMAN, H. B., and FRYE, J. C., 1970, Pleistocene Stratigraphy of Illinois: Illinois State Geological Survey Bulletin 94.
WINTERS, H. A., et al., 1988, Loess stratigraphy in the Midwest: Geological Society of America.

ISGS Codes

ISGS Code and Symbol

Stratigraphic Code	Geo Unit Designation
0630	r