Last glacial loess deposition in central Illinois abruptly slows at ca. 18,750 cal yr BP in response to the Kankakee Torrent

B. Brandon Curry, Hong Wang, Thomas V. Lowell, Benjamin Bates, Nathaniel Norris, Jessica L. Conroy

Research output: Contribution to conferencePaper

Abstract

Smith Lake (40.1484 N, -89.8132 W) occupies a small kettle on the Illinois Episode Till Plain 15 km east of the Illinois River valley, a major source of loess during the last deglaciation. The lake was cored with a Livingston corer in the late 1980's; the initial interest was in obtaining an early and pre-Wisconsin pollen record. Refusal occurred at 11.7 m, and woody plant debris at the base of the core yielded an age of 36,640 cal yr BP (ISGS-2944). With renewed interest in determining the age of deposition of the Peoria Silt (last glacial loess), we returned to Smith Lake in 2017 and obtained new sediment cores using a hydraulically powered Livingston corer. The lake gave up its secrets grudgingly, and refusal occurred at 9 m. We emphasized securing a complete record in the upper part of the sediment record, including: Unit A) 1.81 m of fossiliferous, late Holocene silty clay loam (with an age of 2,360 cal yr BP (UCIAMS-196989) at 1.5 m on carbonized nut shells and wood), B) 0.7 m of gleyed, leached silty clay loam (paleosol) and, C) 6 m of fossiliferous, laminated silt and silt loam. Unit C represents local Illinois Valley loess transported and deposited in the lake. Samples of fine organics sieved from subsamples 3 and 8 cm below the B/C contact yielded median radiocarbon ages of 18,750 and 19,090 cal yr BP. (UCIAMS-196990 and 196991, respectively). The ages are statistically equivalent to the published maximum age of the Kankakee Torrent (median 19,000 cal yr BP; sigma 2 18,800-19,200 cal yr BP). The coincidence of the ages, and the largely slackwater post-Kankakee Torrent record of Glacial Lake Calhoun in the adjacent middle Illinois River valley, may suggest that late glacial loess deposition was curtailed by erosion by the Kankakee Torrent and subsequent adjustments to local hydrology and sedimentation. Our ages agree with estimates of abrupt slowing of loess accumulation based on radiocarbon ages of terrestrial gastropods at Cottonwood School (Nash et al., 2017) and Keller Farm (unpublished).
Original languageEnglish (US)
PagesPaper-No.25-4
DOIs
StatePublished - 2018
EventGSA North-Central 2018 Annual Meeting - Iowa State University, Ames, United States
Duration: Apr 16 2018Apr 17 2018
Conference number: 52

Conference

ConferenceGSA North-Central 2018 Annual Meeting
CountryUnited States
CityAmes
Period4/16/184/17/18

Fingerprint

torrent
Last Glacial
loess
lake
silty clay loam
silt
valley
last deglaciation
glacial lake
nut
late glacial
woody plant
loam
paleosol
river
gastropod
sediment core
hydrology
pollen
Holocene

Keywords

  • ISGS

Cite this

Curry, B. B., Wang, H., Lowell, T. V., Bates, B., Norris, N., & Conroy, J. L. (2018). Last glacial loess deposition in central Illinois abruptly slows at ca. 18,750 cal yr BP in response to the Kankakee Torrent. Paper-No.25-4. Paper presented at GSA North-Central 2018 Annual Meeting, Ames, United States. https://doi.org/10.1130/abs/2018NC-313119

Last glacial loess deposition in central Illinois abruptly slows at ca. 18,750 cal yr BP in response to the Kankakee Torrent. / Curry, B. Brandon; Wang, Hong; Lowell, Thomas V.; Bates, Benjamin; Norris, Nathaniel; Conroy, Jessica L.

2018. Paper-No.25-4 Paper presented at GSA North-Central 2018 Annual Meeting, Ames, United States.

Research output: Contribution to conferencePaper

Curry, BB, Wang, H, Lowell, TV, Bates, B, Norris, N & Conroy, JL 2018, 'Last glacial loess deposition in central Illinois abruptly slows at ca. 18,750 cal yr BP in response to the Kankakee Torrent' Paper presented at GSA North-Central 2018 Annual Meeting, Ames, United States, 4/16/18 - 4/17/18, pp. Paper-No.25-4. https://doi.org/10.1130/abs/2018NC-313119
Curry, B. Brandon ; Wang, Hong ; Lowell, Thomas V. ; Bates, Benjamin ; Norris, Nathaniel ; Conroy, Jessica L. / Last glacial loess deposition in central Illinois abruptly slows at ca. 18,750 cal yr BP in response to the Kankakee Torrent. Paper presented at GSA North-Central 2018 Annual Meeting, Ames, United States.
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abstract = "Smith Lake (40.1484 N, -89.8132 W) occupies a small kettle on the Illinois Episode Till Plain 15 km east of the Illinois River valley, a major source of loess during the last deglaciation. The lake was cored with a Livingston corer in the late 1980's; the initial interest was in obtaining an early and pre-Wisconsin pollen record. Refusal occurred at 11.7 m, and woody plant debris at the base of the core yielded an age of 36,640 cal yr BP (ISGS-2944). With renewed interest in determining the age of deposition of the Peoria Silt (last glacial loess), we returned to Smith Lake in 2017 and obtained new sediment cores using a hydraulically powered Livingston corer. The lake gave up its secrets grudgingly, and refusal occurred at 9 m. We emphasized securing a complete record in the upper part of the sediment record, including: Unit A) 1.81 m of fossiliferous, late Holocene silty clay loam (with an age of 2,360 cal yr BP (UCIAMS-196989) at 1.5 m on carbonized nut shells and wood), B) 0.7 m of gleyed, leached silty clay loam (paleosol) and, C) 6 m of fossiliferous, laminated silt and silt loam. Unit C represents local Illinois Valley loess transported and deposited in the lake. Samples of fine organics sieved from subsamples 3 and 8 cm below the B/C contact yielded median radiocarbon ages of 18,750 and 19,090 cal yr BP. (UCIAMS-196990 and 196991, respectively). The ages are statistically equivalent to the published maximum age of the Kankakee Torrent (median 19,000 cal yr BP; sigma 2 18,800-19,200 cal yr BP). The coincidence of the ages, and the largely slackwater post-Kankakee Torrent record of Glacial Lake Calhoun in the adjacent middle Illinois River valley, may suggest that late glacial loess deposition was curtailed by erosion by the Kankakee Torrent and subsequent adjustments to local hydrology and sedimentation. Our ages agree with estimates of abrupt slowing of loess accumulation based on radiocarbon ages of terrestrial gastropods at Cottonwood School (Nash et al., 2017) and Keller Farm (unpublished).",
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AU - Curry, B. Brandon

AU - Wang, Hong

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AU - Bates, Benjamin

AU - Norris, Nathaniel

AU - Conroy, Jessica L.

PY - 2018

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N2 - Smith Lake (40.1484 N, -89.8132 W) occupies a small kettle on the Illinois Episode Till Plain 15 km east of the Illinois River valley, a major source of loess during the last deglaciation. The lake was cored with a Livingston corer in the late 1980's; the initial interest was in obtaining an early and pre-Wisconsin pollen record. Refusal occurred at 11.7 m, and woody plant debris at the base of the core yielded an age of 36,640 cal yr BP (ISGS-2944). With renewed interest in determining the age of deposition of the Peoria Silt (last glacial loess), we returned to Smith Lake in 2017 and obtained new sediment cores using a hydraulically powered Livingston corer. The lake gave up its secrets grudgingly, and refusal occurred at 9 m. We emphasized securing a complete record in the upper part of the sediment record, including: Unit A) 1.81 m of fossiliferous, late Holocene silty clay loam (with an age of 2,360 cal yr BP (UCIAMS-196989) at 1.5 m on carbonized nut shells and wood), B) 0.7 m of gleyed, leached silty clay loam (paleosol) and, C) 6 m of fossiliferous, laminated silt and silt loam. Unit C represents local Illinois Valley loess transported and deposited in the lake. Samples of fine organics sieved from subsamples 3 and 8 cm below the B/C contact yielded median radiocarbon ages of 18,750 and 19,090 cal yr BP. (UCIAMS-196990 and 196991, respectively). The ages are statistically equivalent to the published maximum age of the Kankakee Torrent (median 19,000 cal yr BP; sigma 2 18,800-19,200 cal yr BP). The coincidence of the ages, and the largely slackwater post-Kankakee Torrent record of Glacial Lake Calhoun in the adjacent middle Illinois River valley, may suggest that late glacial loess deposition was curtailed by erosion by the Kankakee Torrent and subsequent adjustments to local hydrology and sedimentation. Our ages agree with estimates of abrupt slowing of loess accumulation based on radiocarbon ages of terrestrial gastropods at Cottonwood School (Nash et al., 2017) and Keller Farm (unpublished).

AB - Smith Lake (40.1484 N, -89.8132 W) occupies a small kettle on the Illinois Episode Till Plain 15 km east of the Illinois River valley, a major source of loess during the last deglaciation. The lake was cored with a Livingston corer in the late 1980's; the initial interest was in obtaining an early and pre-Wisconsin pollen record. Refusal occurred at 11.7 m, and woody plant debris at the base of the core yielded an age of 36,640 cal yr BP (ISGS-2944). With renewed interest in determining the age of deposition of the Peoria Silt (last glacial loess), we returned to Smith Lake in 2017 and obtained new sediment cores using a hydraulically powered Livingston corer. The lake gave up its secrets grudgingly, and refusal occurred at 9 m. We emphasized securing a complete record in the upper part of the sediment record, including: Unit A) 1.81 m of fossiliferous, late Holocene silty clay loam (with an age of 2,360 cal yr BP (UCIAMS-196989) at 1.5 m on carbonized nut shells and wood), B) 0.7 m of gleyed, leached silty clay loam (paleosol) and, C) 6 m of fossiliferous, laminated silt and silt loam. Unit C represents local Illinois Valley loess transported and deposited in the lake. Samples of fine organics sieved from subsamples 3 and 8 cm below the B/C contact yielded median radiocarbon ages of 18,750 and 19,090 cal yr BP. (UCIAMS-196990 and 196991, respectively). The ages are statistically equivalent to the published maximum age of the Kankakee Torrent (median 19,000 cal yr BP; sigma 2 18,800-19,200 cal yr BP). The coincidence of the ages, and the largely slackwater post-Kankakee Torrent record of Glacial Lake Calhoun in the adjacent middle Illinois River valley, may suggest that late glacial loess deposition was curtailed by erosion by the Kankakee Torrent and subsequent adjustments to local hydrology and sedimentation. Our ages agree with estimates of abrupt slowing of loess accumulation based on radiocarbon ages of terrestrial gastropods at Cottonwood School (Nash et al., 2017) and Keller Farm (unpublished).

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