Sangamonian(?) and Wisconsinan paleoenvironments in Yellowstone National Park

Research Article| June 01, 1986 Sangamonian(?) and Wisconsinan paleoenvironments in Yellowstone National Park RICHARD G. BAKER RICHARD G. BAKER 1Department of Geology, University of Iowa, Iowa City, Iowa 52242 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1986) 97 (6): 717–736. https://doi.org/10.1130/0016-7606(1986)97<717:SAWPIY>2.0.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 RICHARD G. BAKER; Sangamonian(?) and Wisconsinan paleoenvironments in Yellowstone National Park. GSA Bulletin 1986;; 97 (6): 717–736. doi: https://doi.org/10.1130/0016-7606(1986)97<717:SAWPIY>2.0.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 Pollen and plant macrofossil records from Yellowstone National Park, if combined with dated glacial events, provide a paleoenvironmental record of much of the last glacial-interglacial cycle. Bull Lake glaciation has been dated at ∼140,000 yr B.P. Section EP-6 records a late-glacial to full interglacial sequence which is correlated with the Sangamonian interglacial and estimated to be 127,000 yr old at the peak warm period. A prevailing Pseudotsuga-Pinus flexilis-Pinus ponderosa forest suggests that climate was considerably warmer than any in the Holocene. Section EP-5 is somewhat younger, probably late Sangamonian, and shows a forest dominated by Picea, Abies, Pseudotsuga, and a haploxylon Pinus. Slightly cooler conditions than those of the present are indicated.The warmest phase of the Grassy Lake Reservoir section is considered to be ∼82,000 yr old and records a warm interstadial cycle beginning with tundra. The warming sequence is indicated by change to a Picea-Abies-Pinus albicaulis forest and then to a Pinus contorta forest. The cycle ends with forest destruction and a return to open (tundra?) and, presumably, cold conditions.Extremely low values of arboreal pollen indicate that tundra vegetation and cold conditions continued from ∼70,000 to ∼50,000 yr B.P. One cool and, apparently, short interstadial interrupted this extended period of tundra shortly after 68,000 B.P. when a very open parkland of Picea-Abies-Pinus albicaulis appeared.No records of environment are available between ∼50,000 and 30,000 yr B.P. The Pinedale icecap apparently expanded ∼30,000 yr B.P. and lasted until ∼14,000 yr B.P. Late-glacial Picea-Abies-Pinus albicaulis parklands gave way to Pinus contorta forests that have prevailed with minor variation for ∼10,000 yr. 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.