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Published byGrant Hill Modified over 9 years ago
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Timing and extent of Vashon ice east of the Olympic Mountains Porter and Swans on (1998) Moderately fast advance (Seattle at 17.6 ka) Maximum (Tenino) at ~16.9-16.7 ka Moderately fast retreat (16.6 ka) Seattle ice-covered for ~1000 yrs
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Ice sheet present 12,00 0 13,000 14,000 15,000 16,000 17,000 18,000 19,000 20,000 km south of UW Ralph Haugerud (2012 talk, Centralia College) wood peat lake sediments shells Probabilistic ages (OxCal 4.1) reflect uncertainties in initial atmospheric 14 C, marine reservoir correction, & 14 C analyses Similar advance (Seattle 17.6 ka) Maximum (Tenino) ~600 yr later, at ~16.2 ka For Seattle, he inferred a longer glaciation (~1500 yr), but Faster retreat (Seattle ~16.1 ka)
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Puget Lowland under ice. (Blue lines are a model of subglacial drainage.) Image from Ralph Haugerud.
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Puget Lowland radiocarbon dates that bracket Vashon stade = 12,000-15,000 14C yr BP radiocarbon. =15-24 ka luminescence. Blue lines mark latitude and longitude at UW-Seattle. Haugerud, and Porter and Swanson, did not have Hood Canal area data.
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Selected data on Vashon ice timing Blue dots, advance. Yellow dots, recession. Dates in ka. Blue lines mark latitude and longitude at UW- Seattle. Carpenter Lake
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Hood Canal area data on Vashon ice timing Later advance. Very short maximum (Tenino) between ~16.2 and 15 ka. Simultaneous retreat (Tenino to northern Kitsap— timing enigmatic).
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Along Hood Canal, the Vashon stade ice came late and left fast (& late?)
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