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- Title
Timing and extent of early marine oxygen isotope stage 2 alpine glaciation in Skagit Valley, Washington
- Authors
Riedel, Jon L.; Clague, John J.; Ward, Brent C.
- Abstract
Abstract: Twenty-two new radiocarbon ages from Skagit valley provide a detailed chronology of alpine glaciation during the Evans Creek stade of the Fraser Glaciation (early marine oxygen isotope stage (MIS) 2) in the Cascade Range, Washington State. Sediments at sites near Concrete, Washington, record two advances of the Baker valley glacier between ca. 30.3 and 19.5 cal ka BP, with an intervening period of glacier recession about 24.9 cal ka BP. The Baker valley glacier dammed lower Skagit valley, creating glacial Lake Concrete, which discharged around the ice dam along Finney Creek, or south into the Sauk valley. Sediments along the shores of Ross Lake in upper Skagit valley accumulated in glacial Lake Skymo after ca. 28.7 cal ka BP behind a glacier flowing out of Big Beaver valley. Horizontally laminated silt and bedded sand and gravel up to 20 m thick record as much as 8000 yr of deposition in these glacially dammed lakes. The data indicate that alpine glaciers in Skagit valley were far less extensive than previously thought. Alpine glaciers remained in advanced positions for much of the Evans Creek stade, which may have ended as early as 20.8 cal ka BP.
- Subjects
SKAGIT River Valley (B.C. &; Wash.); BRITISH Columbia; WASHINGTON (State); OXYGEN isotopes; GLACIERS; LAKE sediments; GEOLOGICAL time scales; WATERFALLS
- Publication
Quaternary Research, 2010, Vol 73, Issue 2, p313
- ISSN
0033-5894
- Publication type
Article
- DOI
10.1016/j.yqres.2009.10.004