The geoarchaeological record of Holocene sea level change and human occupation of the Texas gulf coast

Abstract

Geoarchaeological data from the central Texas coast suggest fundamental linkages between patterns of Holocene sea level change, evolution of estuarine environments, and human occupation. Three major periods of human occupation of estuary shorelines are identified, based on a series of calibrated radiocarbon ages from 47 stratigraphically discrete cultural components at 23 sites. These periods are separated by apparent hiatuses in occupation, intervals for which there is no chronometric or stratigraphic evidence of significant shoreline residence or of use of estuarine resources. Periods of occupation approximate times of sea level stillstand suggested by geologic data, while intervening periods correlate with proposed episodes of rapid sea level rise. During stillstand, the emergence of highly photosynthetic bay/lagoon shallows supporting nutrient-rich shoreline vegetation provided the basis for a rich, exploitable aquatic biomass. Rapid sea level change is likely to have adversely affected estuarine productivity through inundation of nutrient-rich shallows and through increases in salinity and water turbidity as protective barrier islands were breached by marine transgression. Geoarcheological study of estuarine environments under changing sea level conditions provides a long-term perspective on ecosystemic change relevant to concerns about the expectable effects of global change on the fragile biotic and economic productivity of shallow-water coastlines. ©1997 John Wiley & Sons, Inc.