SURFICIAL GEOLOGY OF THE WAVERLY QUADRANGLE, BREMER COUNTY IOWA

A surficial geologic map of the Waverly Quadrangle was constructed in cooperation with the Iowa Geological and Water Survey, and the USGS (EDMAP). These geologic data are leading to county-specific land use planning tools for the city of Waverly, IA, the Natural Resources Conservation Service (NRCS), and local farmers. The study area was located in northeastern Iowa (Bremer County and Black Hawk Counties). The Waverly 7.5’ Quadrangle covered an area from 42^o 37’30’’ N to 42^o 45’ latitude and 92^o 30’ W to 92^o 22.5’ longitude. The map was completed using ArcGIS software, recent soil survey maps, and field work. Field observations were conducted to characterize the quadrangle’s geologic units.

The Waverly Quadrangle lies in a terrain of dissected Pre-Illinoian glacial deposits that blanket a Paleozoic bedrock surface with significant relief. The study area also represents a portion of the Iowan Erosion Surface and exhibits Wisconsinan and Holocene alluvial surfaces, eolian landforms, and discontinuous outcrops of Paleozoic bedrock. Geologic units within the project area included Paleozoic carbonate bedrock, Pre-Illinoian glacial sediment and alluvium, Wisconsin outwash, loess, Holocene alluvium, and eolian sand. Some of the more important findings from the recent mapping of this quadrangle include: 1) lineated loess-capped, elongated elliptical ridges known as pahas, which are aligned in a northwest-southeast direction and 2) substantially shallow bedrock seen from GEOSAM data. GEOSAM is Iowa’s geologic site and sample cores tracking program.