Alluvial terrace and valley deposits are important sources of information about environmental changes, but the complex ways in which processes operate within river valleys and also in upstream and downstream areas makes interpretation of sediments difficult. Also troublesome are problems in assuring that the dating of sediments is accurate. Radiocarbon-dating methods have somewhat alleviated the latter difficulties, but comprehensive analyses of the dynamics of valley sedimentation based on more accurate chronologies have not been undertaken in many settings. This doctoral dissertation research project will develop a detailed chronology of alluvial change over the last 25,000 for the lower Colorado River valley of the Texas coastal plain. The chronology and analyses will be based on field mapping, on radiocarbon dating of important stratigraphic sections, and on reconstruction of depositional environments and sedimentary provenance for all stratigraphic units. The lower Colorado alluvial record will be compared with radiocarbon-controlled sequences from the upper Colorado River drainage basin and with records of sea-level rise and shoreline change along the Gulf of Mexico to address the relative roles of upstream, downstream, and internal factors as influences on the development of fluvial landforms in the lower Colorado valley. This project will provide valuable information about the timing and processes of landscape change in the study area. Because research methods to be used in this locale have been used elsewhere, this case study will contribute toward comparative analyses of regional landscape evolution and paleoenvironmental change. It also will provide an excellent opportunity for a promising young scholar to continue to develop independent research skills.
