In lieu of an abstract, here is a brief excerpt of the content:

Archaeology and geomorphology! Perhaps nowhere in the world other than the ®oodplain and delta of a major river valley are these sciences so mutually dependent. This is especially true in the dynamic natural environment of the Lower Mississippi Valley, where both sciences have advanced together to a high state. The paths have not been easy, however, and there have been setbacks . This chapter mentions some of the highlights of the last half century of contributions of geomorphology and geology to understanding Mississippi valley landforms, processes, and history as related to human occupation. The chapter is written from the perspective of the author, who has been one of the principal participants in advancing the state of knowledge of alluvial and deltaic geoarchaeology during the last four decades. The Fiskian Era The year was 1944. The Lower Mississippi Archaeological Survey (later renamed Lower Mississippi Survey or LMS), being conducted by Louisiana State University, the University of Michigan, and Harvard University, had been under way for ¤ve years. The purpose of the survey was to investigate the northern two-thirds of the alluvial valley—an area long regarded as one of the principal blind spots in the archaeology of the Southeast (Phillips et al. 1951). According to the authors, this was not due to a lack of work; rather, the work had failed to reveal anything concerning pre-Mississippian cultures. At the same time at LSU, Harold Fisk, a geologist, had just completed a monumental report for the U.S. Corps of Engineers’ Mississippi River Commission on the geology of the alluvial valley of the Mississippi River (Fisk 1944). In this detailed and magni¤cently illustrated report, Fisk presented a re5 Paleogeography and Geomorphology in the Lower Mississippi Valley Roger T. Saucier construction of river meandering at one-hundred-year intervals for the last two thousand years and older channel positions at greater intervals going back about seven thousand years. His interpretation also included subdivision of the deltaic plain into several subdeltas (now generally referred to as delta complexes ). The principal investigators of the LMS—Phil Phillips, Jim Ford, and Jimmy Grif¤n—were not unaware of what Fisk had been working on for two years. They knew of the possibilities of correlating pottery chronology with Mississippi River hydrology, but, according to them, in their ¤eldwork “they had not been as aware as they might have been of the importance of relating sites to local drainage” (Phillips et al. 1951:295). In hindsight, they recognized the tremendous potential in dating sites by their river channel associations. Thus began several decades in which it was virtually unheard of for any archaeologist to investigate a major site without careful consideration of its geomorphic setting and Fisk’s river channel chronology. It should be recalled that, at least until 1952, so-called absolute dating techniques such as radiocarbon assays were still just a dream. Anything that approached producing a numerical age estimate was readily embraced. Problems with Fisk’s chronology soon emerged, however. Those archaeologists who endorsed the concept but urged caution in interpreting results were eventually to have the last word. For example, by 1951 Jim Ford already had experienced dif¤culties in reconciling archaeologically derived dates with Fisk’s channel chronology at the Greenhouse site in central Louisiana (Ford 1951) and questioned whether Fisk’s chronological intervals were really one hundred years long. Several years later, Ford, Phillips, and Bill Haag encountered unreconcilable differences at the Poverty Point period Jaketown site in west-central Mississippi, partly because of the ¤rst radiocarbon dates (Ford et al. 1955). They concluded that Fisk’s chronology was accurate in relative terms but not in calendrical terms. Subsequent Geologic Mapping In 1961, I graduated from LSU, accepted a position in the Geology Branch of the Corps’Waterways Experiment Station in Vicksburg, Mississippi, and began following in the footsteps of Fisk. During the next decade, I rapidly expanded a program of detailed engineering geologic quadrangle mapping that was eventually to cover most of the alluvial valley area (for example, see Saucier 1967). The approach that was used focused on identifying and delineating sedimentary units and their inferred environments of deposition. Stratigraphic relations were a key part of the interpretations, but the Corps’ re52 Roger T. Saucier ports did not discuss chronological implications. Signi¤cant new and exciting chronological concepts began to emerge and appear in the literature, however. For example, strong evidence emerged that the alluvial valley had experienced two rather than just one episode of glacial outwash deposition during...

Share