A CONCEPTUAL MODEL FOR FORMATION OF HANGING BOGS ON THE IOWA
EROSION SURFACE IN EASTERN IOWA. 

Mark W. Smith and William L. Niemann.  
University of Dubuque, Dubuque, Iowa 52001.

The Iowa State Preserve manages a "hanging bog" located south of the Cedar River near Cedar
Rapids, Iowa.  The bog is caused by the flow of groundwater along an impermeable subsurface
layer that intersects a hillside.  Four monitoring wells, including a continuous-measurement
water-level probe, were placed in the bog to record water levels.  The well data was compared to
water levels in the Cedar River and precipitation levels to determine if the above groundwater
was connected with the Cedar River Aquifer.  The site data was used to construct a geologic
cross section of the hillside.  In addition, the geology of the surrounding area was studied using
published maps and the Iowa Geological Survey Bureau's online well-log database (GEOSAM). 
From the site and area data a general conceptual model was developed to explain formation of
hanging bogs on the Iowa Erosion Surface in eastern Iowa.  This model was then used to
compare similar locations along the Cedar River to detect and predict possible additional hanging
bogs.

Keywords:  Bogs, geology, conceptual model, Iowa Erosion Surface