Geoarchaeology: An International Journal, Vol. 15, No. 5, 385–414 (2000)  2000 John Wiley & Sons, Inc. Coastal Paleogeography and Human Occupation of the Western Alaska Peninsula James W. Jordan 1 and Herbert D.G. Maschner 2 1 Department of Geography, University of Wisconsin-Madison. Madison, Wisconsin 53706 2 Department of Anthropology, Idaho State University, Pocatello, Idaho 83209 Geological and archaeological investigations on the western Alaska Peninsula establish re- lationships between postglacial sea level changes and regional settlement patterns, which are linked to the spatial and temporal distribution of marine and estuarine resources. Isostatic emergence dominated relative sea-level changes since deglaciation, but erosional landforms and gaps in the archaeological record suggest that site preservation has varied because of the interplay of eustatic sea level rise, isostatic uplift, and tectonic deformation. Coastal subsidence associated with a major earthquake about 2200 yr B.P. is linked with a 300-year hiatus in the regional archaeological record. A shift from estuarine to littoral and offshore resources following this period demonstrates the impact of such dynamic sea level fluctua- tio ns o n the shape and bio lo gic al pro duc tivity o f the c o astal zo ne. Ho wever, c hanges in village organization, house form, and subsistence base that define several archaeological phases arise from both environmental and sociopolitical instability. Models of culture change should ac- commodate local and regional geological boundary conditions in the North Pacific and simi- larly dynamic settings.  2000 John Wiley & Sons, Inc. INTRODUCTION Identifying the trend and timing of sea level changes is critical for interpreting the spatial and temporal patterns of prehistoric human occupation of coastal zones (Thompson, 1980; Masters and Flemming, 1983; Kraft et al., 1985; Johnson and Stright, 1991; Ricklis and Blum, 1997). Nowhere is this information more relevant than in tectonically and isostatically active areas where the sign and rate of relative changes of sea level vary over time. In such areas, dynamic sea level change affects the geometry of shorelines and embayments, nearshore biological productivity, and the preservation potential and viability of prehistoric settlements. Glaciation and tectonism along the southern margin of Beringia have resulted in a complex pattern of coastal landscape change since the last glacial maximum (LGM; 21,000–14,000 yr B.P.). Sea level changes along the eastern Aleutian arc (Figure 1) are due to tectonic, isostatic, and eustatic processes and have all been active individually and in combination during the late Quaternary (Detterman, 1986). Depositional and erosional shorelines that span the Holocene are preserved in many areas (Winslow, 1991; Jordan, in press) and provide a dynamic geologic