Purpose
Ackmore to Zwingle can be used by anyone to look up Official Series Descriptions (OSDs) for the over 500 soil series that are named in NRCS soil surveys of Iowa.
It is a resource to help archaeologists and geoscientists interpret the lithology, relative age, and stratigraphic nomenclature of the surface geologic materials in which the soils of Iowa are formed. It classifies all defined soil series found in Iowa into Landform Sediment Assemblages (LSA), summarizing parent materials, expected horizonation, and, when possible, approximate age of the soil series.
The site classifies soil series according to their sedimentary, geologic, parent materials as described in the Official Series Descriptions (OSDs) and by the PMAT field in the ISPAID database. Classifications are generalized for series that form predominantly in Wisconsinan and earlier geologic materials in uplands. Series that formed predominantly in Holocene alluvium are assigned as appropriate to a lithostratigraphic unit of the DeForest Formation. See Methods for a discussion of the classification process.
The geodatabase from this project can be downloaded here. It is a sizable download. If you have trouble downloading it, please email ryan-lange@uiowa.edu.
This site is not intended for, and should not be used as, a primary source of information for geologic mapping of Iowa landscapes. The classifications provide, at best, a first approximation of the surface geologic materials that might be expected at a location where an NRCS map unit indicates the occurrence of a given soil series. See Appropriate Use for details.
Changes for the Second Edition
- In addition to their LSA classification, each soil series now has a summary of their Natural Resources Conservation Service (NRCS) official series description (OSD) (USDA 2025a) and horizonation in the table.
- 62 new soil series are included:
Alcester, Algansee, Alvin, Angus, Annieville, Anthon, Augusta Lake, Bearpen, Belmann, Belview, Bentonsport, Birds, Cokato, Coloma, Cornell, Corvuso, Cosmos, Creal, Danbury, Deloit, Derinda, Dinsmore, Donatus, Dorerton, Dunkerton, Eleroy, Eleva, Ella, Fort Dodge, Gillett Grove, Joliet, Kalmarville, Kandiyohi, Kasson, Klingmore, Lerdal, Liston, Marquis, Maxcreek, Maxmore, May City, McCreath, Medo, Melia, Merton, Moland, Moneta, Munterville, Ocheda, Okabena, Omsrud, Pilot Grove, Plano, Plumcreek, Quiver, Reedslake, Ridgeton, Roine, Rushmore, Sigglekov, Swanlake, and Wilsey.
- Castana has been reclassified to Camp Creek > 150 cm.
Additional Notes
- Many of the new series cover small areas that were previously mapped as a different series but were later considered different enough to become their own series (e.g. Anthon from Wadena).
- There are several areas mapped near Mason City as Roseville, but according to searches of the USDA website this does not appear to be an official series yet. Roseville appears to be mapped in close association with Whalan (shallow to bedrock) and Waubeek (shallow to till) soils.
- We highly recommend using the USDA Web Soil Survey (USDA 2025b). Artz (2011) has a tutorial as well as a lot of other useful information.
- If there are errors in this document or you think a soil series is misclassified in Ackmore to Zwingle, please email ryan-lange@uiowa.edu.