Extensive Early and Middle Wisconsin Glaciation on the Western Olympic Peninsula, Washington, and the Variability of Pacific Moisture Delivery to the Northwestern United States

• Published in: Quaternary Research
• Main Author: Thackray, Glenn D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2001
• Subjects: Pacific; North Atlantic
• Online Access: http://dx.doi.org/10.1006/qres.2001.2220; http://api.elsevier.com/content/article/PII:S0033589401922203?httpAccept=text/xml; http://api.elsevier.com/content/article/PII:S0033589401922203?httpAccept=text/plain; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589400028404

Abstract Large glaciers descended western valleys of the Olympic Mountains six times during the last (Wisconsin) glaciation, terminating in the Pacific coastal lowlands. The glaciers constructed extensive landforms and thick stratigraphic sequences, which commonly contain wood and other organic detritus. The organic material, coupled with stratigraphic data, provides a detailed radiocarbon chronology of late Pleistocene ice-margin fluctuations. The early Wisconsin Lyman Rapids advance, which terminated prior to ca. 54,000 14 C yr B.P., represented the most extensive ice cover. Subsequent glacier expansions included the Hoh Oxbow 1 advance, which commenced between ca. 42,000 and 35,000 14 C yr B.P.; the Hoh Oxbow 2 advance, ca. 30,800 to 26,300 14 C yr B.P.; the Hoh Oxbow 3 advance, ca. 22,000–19,300 14 C yr B.P.; the Twin Creeks 1 advance, 19,100–18,300 14 C yr B.P.; and the subsequent, undated Twin Creeks 2 advance. The Hoh Oxbow 2 advance represents the greatest ice extent of the last 50,000 yr, with the glacier extending 22 km further downvalley than during the Twin Creeks 1 advance, which is correlative with the global last glacial maximum. Local pollen data indicate intensified summer cooling during successive stadial events. Because ice extent was diminished during colder stadial events, precipitation—not summer temperature—influenced the magnitude of glaciation most strongly. Regional aridity, independently documented by extensive pollen evidence, limited ice extent during the last glacial maximum. The timing of glacier advances suggests causal links with North Atlantic Bond cycles and Heinrich events.