"the spatial distribution of tree taxa (e.g. willow, cottonwood, boxelder,sycamore, maple, pin oak, ash, pecan, honey locust, elm, hackberry, buroaks) and herbaceous plant resources (e.g. grape, blackberry,
raspberry, etc.) across the valley floor also supports a tripartite topographically based division of the floodplain into three zones, which I have called deep wetlands, shallow wetlands and dry land (encompassing forests, grasslands, and clearings"