Basin-scale reconstruction of the geological context of human settlement: an example from the lower Mississippi Valley, USA

Large river valleys integrate hydroclimatic change differently than smaller ones. Whereas sedimentary deposits in smaller valleys serve to record temporally short-lived and/or low-amplitude hydrological and geomorphic responses, larger valleys are relatively insensitive to changes at these scales. However, because of their size, larger valleys archive sedimentary records of longer-term, geographically extensive flooding and climate-related landscape evolution. Recent work in the Upper Tensas Basin of the lower Mississippi River Valley, USA, demonstrates the utility of analyzing sediments from a large, geomorphically and fluvially complex river basin as a proxy for significant climatic and landscape changes and their relation to human history. A similar to 6000 year sedimentary archive is used to explore the interplay between climate change, landscape evolution, and human responses to changing environmental parameters. Once the Mississippi River basin stabilized following glacial retreat and deceleration of sea-level rise, the history of the river and its inhabitants was dominated by long periods of landscape stability punctuated by episodes of significant landform alteration. Modifications of the landscape are correlated with intervals of rapid climate change recorded in globally distributed multiproxy data sets. Periods of significant landscape instability and fluvial re-adjustment are recorded for the periods ca 4800-3800, 3000-2500, and 1000-800 cal BR These punctuations in the history of the lower Mississippi Valley are related to periods of major cultural transformation and suggest climate change plays a significant role in the long-term history of human occupation in this river valley. This research demonstrates how geoarcheology can provide information on human-environmental relationships and long-term landscape histories at temporal and spatial scales relevant to understanding cultural responses to climate change. (C) 2008 Elsevier Ltd. All rights reserved.