Stratigraphic and geomorphologic evidence of three MIS 2 glacial advances in the South Fork Hoh River valley, Olympic Mountains, Washington, USA

• Published in: Quaternary Research
• Main Authors: Wyshnytzky, Cianna E., Rittenour, Tammy M., Thackray, Glenn D., Shulmeister, James
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2019
• Subjects: Hummocky Moraine; Blue Glacier; Teton Range; Annual Mass; Pinedale; Rates; Chronologies; Yellowstone; Sediments; Iceland; South Fork; glacier
• Online Access: https://espace.library.uq.edu.au/view/UQ:7720246

The geomorphology and stratigraphy of the South Fork Hoh River (SF Hoh), Olympic Mountains, Washington, allow for greater understanding of Marine Oxygen Isotope Stage 2 (MIS 2) ice fluctuations, glacial dynamics, and sedimentation. Age control from optically stimulated luminescence and radiocarbon dating constrains deposited sediments associated with four Late Pleistocene ice-marginal positions that formed under reduced ice volume conditions compared with MIS 3-5 glaciers in the same drainage. The earliest MIS 2 ice margin extended into the main Hoh River valley (pre-SF 1, 28 ka to >23.0 ka). After retreat, the ice occupied three closely spaced ice-marginal positions (SF 1-3) that range in age from 22.0 ka to shortly after 18.7 ka. While the SF 1 and SF 3 positions were previously identified as the Twin Creeks I and II positions, the intermediate SF 2 position had not been recognized. Moraines are composed of poorly sorted, but stratified, sediment and few tills. Diamicton units show evidence of water reworking. This research documents a detailed record of MIS 2 glaciation in a maritime setting in western North America and provides evidence of rapid MIS 2 ice-marginal fluctuations that likely reflect responses to millennial-scale climatic fluctuations and may be relevant to understanding other complex MIS 2 moraine sequences.