Iowa DNR
River & Stream Biological Monitoring
Fish and Benthic Macroinvertebrate Surveys
Physical Habitat Assessments

Ecoregion 47c : Iowan Surface

Ecoregion Map

Ecoregion Characteristics

Landform Description
Irregular to smooth plains. Elevation 900-1200 ft.
Surficial Materials
Thin loess over loamy till.
Mollisols (Hapludolls, Argiudolls) {Kenyon-Floyd-Clyde}
Annual precipitation 31-33 in. Freeze free: 145-155 days.
Potential Vegetation
Bluestem prairie, oak-hickory forest
Predominant Land Use
The Iowan Surface ecoregion is a geologically complex region located between the bedrock-dominated landforms of the Paleozoic Plateau region and the relatively recent glacial drift landforms of the Des Moines Lobe. The southern and southeastern border of this ecoregion is irregular and crossed by major northwest- to southeast-trending stream valleys. In the northern portion of the region, the glacial deposits are thin, and shallow limestone bedrock creates karst features such as sinkholes and sags. There are no natural lakes of glacial origin in this region, but overflow areas and backwater ponds occur on some of the larger river channels contributing to some diversity of aquatic habitat and a large number of fish species.