HR: 0800h
AN: GC41A-0095    [Abstracts]
TI: Neoglacial fluctuations of Deming Glacier, Mt. Baker, Washington USA.
AU: * Osborn, G
EM: osborn@ucalgary.ca
AF: Geology and Geophysics, University of Calgary, Calgary, AB T2N 1N4, Canada
AU: Menounos, B
EM: menounos@unbc.ca
AF: Geography, University of Northern British Columbia, Prince George, BC V2N 4Z9, Canada
AU: Scott, K
EM: kscott@usgs.gov
AF: Cascades Volcano Observatory, U.S. Geological Survey, Vancouver, WA 98683, United States
AU: Clague, J J
EM: jclague@sfu.ca
AF: Department of Earth Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
AU: Tucker, D
EM: tuckerd@openaccess.org
AF: Department of Geology, Western Washington University, Bellingham, WA 98225, United States
AU: Riedel, J
EM: Jon_Riedel@nps.gov
AF: National Park Service, North Cascades National Park, Marblemount, WA 98267, United States
AU: Davis, P
EM: pdavis@bentley.edu
AF: Natural Sciences, Bentley College, Waltham, MA 02452-4705, United States
AB: Deming Glacier flows from the upper west slopes of Mt. Baker, a stratovolcano in the Cascade Range of Washington, USA. The north and south lateral moraines of Deming Glacier are composed of at least four tills separated by layers of detrital wood and sheared stumps in growth position. The stratigraphy records fluctuations of the glacier during the Holocene. The outer ten rings of an in situ stump from the middle wood layer, which is about 40 m below the north lateral moraine crest and 1.2 km downvalley from the present glacier terminus, yielded an age of 1750 ± 50~~ ¹⁴C yr BP [1810-1550 cal yr BP]. The stump revealed at least 300 rings and thus records a period of landscape stability and relatively restricted glaciation for several hundred years prior to ca. 1750 ¹⁴C yr BP . Samples from the lowest wood layer also have been submitted for radiocarbon dating. Outer rings of detrital wood samples collected from two wood mats exposed in the south lateral moraine, 2.3 km downvalley of the glacier terminus, returned radiocarbon ages of 1600 ± 30~~ ¹⁴C yr BP [1550- 1410 cal yr BP] and 430 ± 30~~ ¹⁴C yr BP [AD 1420-1620]. These data indicate that Deming Glacier advanced over a vegetated moraine sometime after 1810 cal yr BP to a position less extensive that it achieved at the peak of the Little Ice Age. The glacier then receded before it began its final and most extensive Holocene advance after AD 1420. The older advance is correlative with the 'First Millennium AD' advance, recently recognized throughout western North America. The younger advance coincides with an advance of Mt. Baker's Easton Glacier [AD 1430-1630], and advances of many alpine glaciers elsewhere in western North America. Our data suggest that glaciers on Mt. Baker fluctuated in a similar manner to alpine glaciers in the Coast Mountains of British Columbia and in other mountain ranges of northwest North America during Neoglaciation.
DE: 0720 Glaciers
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1621 Cryospheric change (0776)
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting