A RECORD OF DYNAMIC CHANGES IN MORPHOLOGY FOR THE LATE HOLOCENE MISSOURI RIVER AND HABITAT IMPLICATIONS

We mapped alluvium on the Carrollton East, Carrollton West, Waverly and Grand Pass Quadrangles in the Missouri River Valley allostratigraphically to test if four morphologies found previously on the adjacent Miami Station and Malta Bend Quadrangles extend further up valley, or constitute a local anomaly. Mapping utilized the use of drill hole data, aerial photographs, satellite images and existing soil maps. Map units are broken down into: Primary abandoned channel fill (both passive and active), Secondary abandoned channel fill, point bar and splay units. The first morphology has channels of very thin width that are unusually deep (around eight meters) in cross section and are found in the northern part of the valley fill. The second morphology consists of wide-sweeping meander loops that have no restriction to locale in the valley. The third morphology has tight meander loops and typically contains passive fill of around eight meters. The fourth, most recent morphology is the island-braided river Lewis and Clark traveled Our preliminary study supports the hypothesis that the four meander trends recognized on the Miami Station Quadrangle are not just a local anomaly, but show regional trends in river pattern. These observations have important ramifications for ongoing land acquistion efforts aimed at comprehensive habitat restoration efforts throughout the Missouri Valley, as these morphologies produce sustantially different habitat substrates. In particular, the size and morphology of channel fills control the distribution of surface water retention and related wetland vs dryland habitat.