HR: 10:50h
AN: C42A-03 INVITED     [Abstracts]
TI: POST-LITTLE-ICE-AGE LANDSCAPE AND GLACIER CHANGE IN GLACIER BAY NATIONAL PARK: DOCUMENTING MORE THAN A CENTURY OF VARIABILITY WITH REPEAT PHOTOGRAPHY
AU: * Molnia, B F
EM: bmolnia@usgs.gov
AF: USGS, 926A National Center, Reston, VA 20192 United States
AU: Karpilo, R D
EM: ron_karpilo@partner.nps.gov
AF: National Park Service, 12795 W Alameda Parkway, Denver, CO 80225 United States
AU: Pranger, H S
EM: hal_pranger@nps.gov
AF: National Park Service, 12795 W Alameda Parkway, Denver, CO 80225 United States
AB: Historical photographs, many dating from the late-19th century are being used to document landscape and glacier change in the Glacier Bay area. More than 350 pre-1980 photographs that show the Glacier Bay landscape and glacier termini positions have been acquired by the authors. Beginning in 2003, approximately 150 of the sites from which historical photographs had been made were revisited. At each site, elevation and latitude and longitude were recorded using WAAS-enabled GPS. Compass bearings to photographic targets were also determined. Finally, using the historical photographs as a composition guide, new photographs were exposed using digital imaging and film cameras. In the laboratory, 21st century images and photographs were compared with corresponding historical photographs to determine, and to better understand rates, timing, and mechanics of Glacier Bay landscape evolution, as well as to clarify the response of specific glaciers to changing climate and environment. The comparisons clearly document rapid vegetative succession throughout the bay; continued retreat of larger glaciers in the East Arm of the bay; a complex pattern of readvance and retreat of the larger glaciers in the West Arm of the bay, coupled with short-term fluctuations of its smaller glaciers; transitions from tidewater termini to stagnant, debris-covered termini; fiord sedimentation and erosion; development of outwash and talus features; and many other dramatic changes. As might be expected, 100-year-plus photo comparisons show significant changes throughout the Glacier Bay landscape, especially at the southern ends of East and West Arms. Surprisingly, recent changes, occurring since the late-1970s were equally dramatic, especially documenting the rapid thinning and retreat of glaciers in upper Muir Inlet.
DE: 1815 Erosion and sedimentation
DE: 1824 Geomorphology (1625)
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
DE: 1894 Instruments and techniques
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting