Reinterpretation of the Robein and Plano Silts, northeastern Illinois
Conference
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· Geol. Soc. Am., Abstr. Programs; (United States)
OSTI ID:6646222
Reinterpretation of till stratigraphy in northern Illinois and recently obtained radiocarbon dates suggest the Plano Silt is lithologically and stratigraphically indistinguishable from the Robein Silt. These recent data suggest colluvial silt and organic-rich sediment were deposited in most of the northern Illinois between >50,000 and 23,000 RCBP. This age range agrees with radiocarbon dates from the Mid-Wisconsinan Sidney Interstadial Soil of the Huron-Erie Lobe. Altonian (Early to Mid-Wisconsinan)-age till associated with the Lake Michigan Lobe has not yet been identified. Horberg and others recognize in northeastern Illinois a single basal Wisconsinan organic-rich zone; peat, silt and loess of the Farmdalian Substage were interpreted to overlie Sangamon Soil developed in Illinoian drift. They also interpreted a reddish-brown diamicton overlying the Plano Silt at its type section as the Capron Till Member of late Altonian age. The new data support the earlier interpretation of a single organic-rich deposit between Wisconsinan and Illinoian drifts. The Plano Silt should be abandoned as a rock-stratigraphic unit. The Robein Silt includes colluvium and organic-rich sediment not only of Farmdalian age, but also Altonian age in most of northern Illinois, similar to the rest of the upper Mississippi River Valley. The evidence of nearly continuous Robein deposition restricts possible Altonian-age glacial deposits to a narrow band on Capron Ridge in northern Illinois and southern Wisconsin.
- Research Organization:
- Illinois State Geological Survey, Champaign (USA)
- OSTI ID:
- 6646222
- Report Number(s):
- CONF-8510489-
- Conference Information:
- Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
- Country of Publication:
- United States
- Language:
- English
Similar Records
[sup 14]C and [sup 10]Be evidence for no incursion of the Lake Michigan lobe in northern Illinois from ca. 170 to 25 ka
Quaternary landscape evolution of the Turkey River Valley, northeastern Iowa
Geomorphic history and Pleistocene stratigraphy of the Pecatonica River valley, Wisconsin and Illinois
Conference
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Thu Mar 31 23:00:00 EST 1994
· Geological Society of America, Abstracts with Programs; (United States)
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OSTI ID:6924887
Quaternary landscape evolution of the Turkey River Valley, northeastern Iowa
Thesis/Dissertation
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Wed Dec 31 23:00:00 EST 1986
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OSTI ID:6251393
Geomorphic history and Pleistocene stratigraphy of the Pecatonica River valley, Wisconsin and Illinois
Thesis/Dissertation
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Sun Dec 31 23:00:00 EST 1978
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OSTI ID:5473336