Author(s):
Frederick E. Nelson* - University of Delaware
Michael T. Walegur - University of Delaware
Kim J. Park Nelson - University of Minnesota
Abstract:
Locational data were obtained for 96 periglacial blockfields in the Appalachian Mountains of eastern USA using "TerraServer," a Virtual Globes (VGs) resource for viewing air-photo and satellite imagery. The elevation of Appalachian blockfields south of the Last Glacial Maximum border parallels regional gradients of contemporary mean July, summer, and annual temperature. July temperature reductions inferred from paleoecological studies indicate that the median elevation of blockfields throughout the Appalachians lay at or above timberline during the Last Glacial Maximum (LGM). Paleotemperatures calculated using known Appalachian lapse rates and published LGM temperature departures indicate that most blockfields in the study area were formed in association with permafrost. Allochthonous blockfields appear to be constituent elements of periglacial "form communities" developed under severely cold conditions, and are useful indicators of Pleistocene permafrost conditions. Internet-based VGs can be used to create generalized reconnaissance-level data bases of large-scale periglacial landforms and hillslope features over large areas. Complementary use of Virtual Globes technology and spatial-analytic techniques holds considerable potential for addressing the broad-scale problems with which traditional climatic geomorphology is concerned.
