USING REPEAT PHOTOGRAPHY TO DOCUMENT THE LANDSCAPE AND VEGETATIVE EVOLUTION OF THE GLACIER BAY AREA, GLACIER BAY NATIONAL PARK, ALASKA

Historical photographs of the Glacier Bay area, made between the l880s and 1980 by mapping surveys, early scientific expeditions, geological and glaciological investigators, and early tourists, are being used as part of an integrated effort to characterize the evolution of Glacier Bay’s landscapes and vegetation. The historical photographs, obtained from multiple sources, including several national archives, are analyzed to document former landscape parameters including: glacier extent and terminus position, vegetation distribution and type, wetland location and extent, and sediment distribution. Nearly all of the historical photographs lack metadata, most significantly camera, lens, and film data, and the geographic coordinates of the photo-point from which the photographs were made.

Field investigations conducted in 2003 and 2004, with historical photographs in hand, identified and revisited more than 100 photo-points where historical photographs were made. The latitude, longitude, and elevation of each photo-point was determined with G.P.S. Similarly, the bearing from the photo-point to the geographic feature corresponding to the center of the historical photograph was determined with Brunton Compass or G.P.S. At each location, a suite of digital images and color-film photographs were made of the same areas displayed in the historical photographs, often using lenses of different focal length. As many of the historical photographs were made with panoramic or mapping cameras, mosaicing and cropping were frequently necessary to reproduce the historical field-of-view.

Comparisons of historical and modern photo-pairs document the timing and magnitude of post-Little-Ice-Age glacier retreat and subsequent variability. Also evident is the rapid influx of vegetation and the transformation and progression from essentially bare bedrock to forest. Annotated photo-pairs are being posted on publicly-accessible websites and provided to National Park Service managers and interpreters. In 2004, similar studies are being initiated in Kenai Fjords and Denali National Parks.