QUATERNARY STRATIGRAPHIC BASIS FOR DELINEATING HYDROGEOMORPHIC PATCHES IN THE UPPER MISSISSIPPI RIVER VALLEY

The Upper Mississippi River Valley (UMV) has witnessed significant changes in fluvial style during the last glacial-interglacial cycle, including changes in stream gradient, channel pattern, sediment lithology, and location of depocenters. These changes are reflected in the landforms and sediments of the modern valley, and have produced associations of landforms and underlying sediments (Landform Sediment Associations and Allostratigraphic units) that are predictable and mapable at a variety of scales. These stratigraphic frameworks and valley-wide mapping efforts have been used extensively for managing the valley’s cultural resources over the past two decades. Many physical characteristics used to distinguish units in these stratigraphic frameworks also influence groundwater movement, soils, and biogeochemical processes that interact with the river hydrology to produce hydrogeomorphic patches. Hydrogeomorphic patches are the physical template for the ecological functions performed in “functional process zones” which are a research province of aquatic ecologists. We provide examples of the application of existing UMV alluvial stratigraphy and geomorphic mapping to the identification of hydrogeomorphic patches in the context of river management and restoration.