The topography of the Driftless Area, which was never glaciated during the Quaternary Period, is dominated by fluvial incision into flat-lying Paleozoic bedrock, resulting in deep, dendritic valleys. Local relief reaches 115 meters. Sediment coring across the region reveals that the geology of unconsolidated surficial materials is often controlled by the geomorphology. Uplands are capped by loess, colluvium blankets the slopes, and floodplains are marked by substantial filling with alluvial sediments. Three separate county maps are available for Vernon, Crawford, and Richland Counties. A single accompanying report describes map units across these geomorphically-similar counties and is published with the Vernon County map.