Late Pliocene Dawson Cut Forest Bed and new tephrochronological findings in the Gold Hill Loess, east-central Alaska

Abstract

Research Article| January 01, 2009 Late Pliocene Dawson Cut Forest Bed and new tephrochronological findings in the Gold Hill Loess, east-central Alaska T.L. Péwé; T.L. Péwé 1Department of Geology, Arizona State University, Tempe, Arizona 85287, USA *Deceased. Search for other works by this author on: GSW Google Scholar J.A. Westgate; J.A. Westgate † 2Department of Geology, University of Toronto, Toronto, Ontario M5S 3B1, Canada †E-mail: westgate@geology.utoronto.ca. Search for other works by this author on: GSW Google Scholar S.J. Preece; S.J. Preece 2Department of Geology, University of Toronto, Toronto, Ontario M5S 3B1, Canada Search for other works by this author on: GSW Google Scholar P.M. Brown; P.M. Brown 3Rocky Mountain Tree-Ring Research, Inc., 2901 Moore Lane, Fort Collins, Colorado 80526, USA Search for other works by this author on: GSW Google Scholar S.W. Leavitt S.W. Leavitt 4Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Author and Article Information T.L. Péwé *Deceased. 1Department of Geology, Arizona State University, Tempe, Arizona 85287, USA J.A. Westgate † 2Department of Geology, University of Toronto, Toronto, Ontario M5S 3B1, Canada S.J. Preece 2Department of Geology, University of Toronto, Toronto, Ontario M5S 3B1, Canada P.M. Brown 3Rocky Mountain Tree-Ring Research, Inc., 2901 Moore Lane, Fort Collins, Colorado 80526, USA S.W. Leavitt 4Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona 85721, USA †E-mail: westgate@geology.utoronto.ca. Publisher: Geological Society of America Received: 05 Sep 2007 Revision Received: 09 Feb 2008 Accepted: 22 Apr 2008 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2008 Geological Society of America GSA Bulletin (2009) 121 (1-2): 294–320. https://doi.org/10.1130/B26323.1 Article history Received: 05 Sep 2007 Revision Received: 09 Feb 2008 Accepted: 22 Apr 2008 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation T.L. Péwé, J.A. Westgate, S.J. Preece, P.M. Brown, S.W. Leavitt; Late Pliocene Dawson Cut Forest Bed and new tephrochronological findings in the Gold Hill Loess, east-central Alaska. GSA Bulletin 2009;; 121 (1-2): 294–320. doi: https://doi.org/10.1130/B26323.1 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 Thick loess deposits in the Fairbanks region of interior Alaska are a rich source of information on past climates and environments during the late Cenozoic, and the numerous distal, silicic tephra beds preserved within them offer the potential for good chronological control. The Dawson Cut Forest Bed lies in the lower part of this loess cover. Plant macrofossils consist of Picea glauca, Picea mariana, Betula papyrifera, and Populus balsamifera but no Pinus. These fossils, together with the abundance and size of spruce remains, pollen, tree-ring characteristics, and δ13C values of spruce wood, demonstrate that the boreal forest represented by the Dawson Cut Forest Bed was similar to the modern boreal forest of central Alaska. Warming conditions during the early part of the Dawson Cut Interglaciation initiated thawing of permafrost and melting of ground ice, as evidenced in the presence of ice-wedge casts and major erosion of the lower Gold Hill Loess. Tephrochronological, magnetostratigraphic, and glass fission-track dating studies in the Fairbanks area and at the Palisades site on the Yukon River in central Alaska suggest an age for the Dawson Cut Forest Bed of ca. 2 Ma. Hence, the northern boreal forest of northwestern North America, as we know it today, has a long history that probably extends back to at least 2 Ma. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.