Grantee Research Project Results
Late Quaternary Sea Level Change in Southern Beringia: Coastal Paleogeography of the Western Alaska PeninsulaEPA Grant Number: U915030
Title: Late Quaternary Sea Level Change in Southern Beringia: Coastal Paleogeography of the Western Alaska Peninsula
Investigators: Jordan, James W.
Institution: University of Wisconsin - Madison
EPA Project Officer: Manty, Dale
Project Period: January 1, 1996 through January 1, 1997
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1996)
Research Category: Academic Fellowships , Fellowship - Geography , Ecological Indicators/Assessment/Restoration
The objective of this research project is to determine the long-term (Holocene) trend of sea level in the context of isostatic, tectonic, and climatologic controls, which will serve as the basis for assessing the geomorphic effects and ecological implications of sea level fluctuation since the late Pleistocene deglaciation of the southern margin of Beringia.Approach:
Regional sea level data are equivocal, showing both emergent and submergent trends across 35 years of tide gauge data (Emery and Aubrey, 1991). A general eustatic model of sea level rise since the last glacial maximum is inappropriate for coasts of the north Pacific because of active tectonism and the effects of glacial isostasy. Long-term sea level fluctuations must be determined from terrestrial evidence preserved in coastal plain settings (van de Plassche, 1986). A lithostratigraphic model was constructed to explain the sequence of sedimentary facies encountered from the lowest to highest marine and glaciomarine deposits. Geomorphic mapping, shallow coring of coastal marshes, and sampling of bluff exposures provide data on the elevation of deposits and their relationship to former sea levels. The identification of biostratigraphic facies (macrofossils and diatoms) will help define transitions between salt- and freshwater environments. The apparent ages for deposits or features will be determined by conventional and AMS 14C dating of organic samples. Volcanic ash, soil, and archaeological stratigraphy provide relative age control, where datable organic materials are absent. A regional sea level curve will be developed through correlation of these data sets across the study area (c. 300 km2), and will allow a paleogeographic reconstruction of coastal environments to be made. Sea level changes linked to seismic events will be identified from core and bluff stratigraphy where possible, and will strengthen predictions of the magnitude and rate of future changes.Supplemental Keywords:
fellowship, Alaska, sea level, sea level changes, ecological implications, geomorphic effects, north Pacific.