UNDERGRADUATES PRODUCE GASTINEAU CHANNEL FORMATION WEBSITE FOR IDENTIFICATION OF EARLY HOLOCENE MARINE SUBFOSSILS FROM AN UPLIFTED GLACIOMARINE DIAMICTON, JUNEAU, ALASKA

Following the Last Glacial Maximum (LGM), the Gastineau Channel Formation (GCF) was deposited between 12,000 and 10,000 years ago as retreating tidewater glaciers calved icebergs into deepening fjords, when rising sea level flooded the Juneau area (Miller, 1973, 1975). The three facies of this formation contain ice-rafted debris that was dumped into bluish-gray marine silt and sand. These sediments provide the early Holocene matrix for subfossils of marine mollusks, barnacles and foraminiferans. This glaciomarine diamicton is exposed throughout the Juneau area at elevations up to 230m and indicates that LGM ice-loading, locally depressed the crust well below worldwide sea level lowering of -120m.

Field studies undertaken by University Alaska Southeast environmental science program undergraduates, provided samples from throughout the region. Thilenius and Connor have identified the faunal constituents and reconstructed their distributions and ranges. Bleidorn created web accessible taxonomic keys and linked them with photomicrographs to facilitate comparison of faunal constituents from other early Holocene fjord deposits elsewhere in the region. Knuth created a new GIS map that provides site location data, early Holocene inundation visualization, and the areal extent of the facies in the GCF. The website enables visitors to key out species, locate invertebrate-rich outcrop locations, navigate through GCF stratigraphy, radiocarbon information, and learn about the areal extent of these uplifted fjord sediments.

It is hoped that this website will be provide a useful, easily accessible resource for Quaternary researchers working on post-LGM records of climate variability in the region. http://www.uas.alaska.edu/envs/gastineau_formation/index.html