Research Article| February 01, 1991 Mid-Wisconsinan stratigraphy and paleoenvironments at the St. Charles site in south-central Iowa R. G. BAKER; R. G. BAKER 1Departments of Geology and Botany, University of Iowa, Iowa City, Iowa 52242 Search for other works by this author on: GSW Google Scholar D. P. SCHWERT; D. P. SCHWERT 2Department of Geology, North Dakota State University, Fargo, North Dakota 58105 Search for other works by this author on: GSW Google Scholar E. A. BETTIS, III; E. A. BETTIS, III 3Iowa Department of Natural Resources, Geological Survey Bureau, 123 North Capitol Street, Iowa City, Iowa 52242 Search for other works by this author on: GSW Google Scholar T. J. KEMMIS; T. J. KEMMIS 3Iowa Department of Natural Resources, Geological Survey Bureau, 123 North Capitol Street, Iowa City, Iowa 52242 Search for other works by this author on: GSW Google Scholar D. G. HORTON; D. G. HORTON 4Department of Botany, University of Iowa, Iowa City, Iowa 52242 Search for other works by this author on: GSW Google Scholar H. A. SEMKEN H. A. SEMKEN 5Department of Geology, University of Iowa, Iowa City, Iowa 52242 Search for other works by this author on: GSW Google Scholar Author and Article Information R. G. BAKER 1Departments of Geology and Botany, University of Iowa, Iowa City, Iowa 52242 D. P. SCHWERT 2Department of Geology, North Dakota State University, Fargo, North Dakota 58105 E. A. BETTIS, III 3Iowa Department of Natural Resources, Geological Survey Bureau, 123 North Capitol Street, Iowa City, Iowa 52242 T. J. KEMMIS 3Iowa Department of Natural Resources, Geological Survey Bureau, 123 North Capitol Street, Iowa City, Iowa 52242 D. G. HORTON 4Department of Botany, University of Iowa, Iowa City, Iowa 52242 H. A. SEMKEN 5Department of Geology, University of Iowa, Iowa City, Iowa 52242 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1991) 103 (2): 210–220. https://doi.org/10.1130/0016-7606(1991)103<0210:MWSAPA>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation R. G. BAKER, D. P. SCHWERT, E. A. BETTIS, T. J. KEMMIS, D. G. HORTON, H. A. SEMKEN; Mid-Wisconsinan stratigraphy and paleoenvironments at the St. Charles site in south-central Iowa. GSA Bulletin 1991;; 103 (2): 210–220. doi: https://doi.org/10.1130/0016-7606(1991)103<0210:MWSAPA>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract A sequence of loess-mantled sediments exposed along Clanton Creek provides the first evidence of fluvial, pedologic, and biotic environments before the last glacial maximum in south-central Iowa. Two fining-upward fluvial sequences, one inset into the other, are exposed. Radiocarbon ages indicate that the alluvial fills are about 34,000 yr old.Basal gravel in the oldest fill contains well-preserved mammoth (Mammuthus) bones. Sparse seeds from this horizon suggest weedy flood-plain conditions. The younger alluvial fill contains well-preserved pollen, plant macrofossils, and insects. The pollen is dominated by nonarboreal taxa and Pinus, suggesting a prairie border or savanna environment. Vascular-plant and bryophyte macofossils indicate a variety of aquatic and marsh environments on the flood plain. Insects are mostly sympatric in mixed conifer and hardwood forest that extends along latitude 47° to 49° between eastern North Dakota and New England, but forest beetles are rare, and the fauna is dominated by openground forms. The site is interpreted as an open flood plain dotted with marshes and oxbow lakes; it was surrounded by open woodland or savanna similar to that in north-eastern North Dakota at present. July temperatures at the St. Charles site were probably 3 to 5 C° cooler than those at present.The pre-loess stratigraphy of the site differs markedly from that of upland sites and demonstrates that correlation between upland and lowland sequences cannot be done without adequate dating. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.