Degree Type

Dissertation

Date of Award

1981

Degree Name

Doctor of Philosophy

Department

Agronomy

Abstract

Geomorphic, stratigraphic, and pedologic investigations were conducted in the geographic area along the Iowa and Cedar Rivers known as the Lake Calvin region. The landscapes studied included the terraces of the Iowa and Cedar Rivers and their tributary streams and the uplands surrounding the Lake Calvin basin;The uplands surrounding the Lake Calvin basin descend to a loess-mantled high terrace in a series of stepped geomorphic surfaces. Aeolian sand deposited by locally deflected winds was found throughout the uplands and on the loess-mantled high terrace. A paleosol developed in alluvium was identified on the high terrace throughout the Iowa River portion of the loess-mantled high terrace;The absence of a loess mantle on the low and intermediate terraces indicated that these surfaces were younger than 14,000 years before present. Based on similar stratigraphic relationships and elevations, the low, intermediate, and Iowa-Cedar terraces were considered contemporaneous terraces which occupy separate river valleys in the Lake Calvin basin. The low, intermediate, and Iowa-Cedar terraces were combined and renamed the low terrace;No evidence of fluvial sediments was found in a transect which traversed the sag in the divide near Columbus Junction, previously thought to be the outlet to Lake Calvin. Till deposits in the vicinity of Columbus Junction were identified as Pre-Illinoian, undifferentiated tills of the Wolf Creek Formation;Selected soils in the uplands were partitioned into three groups on the basis of their stratigraphy and parent material. Soil groups No. I and III consisted of well-drained soils on gently sloping convex uplands. Soil group No. II consisted of well-drained soils on gently sloping positions on the high terrace and soils with restricted drainage on the nearly level positions on the high terrace. The group No. II and III soils contained zones of sand below the loess or zones or bands of intercalated sand in the loess. Significant differences in the solum thickness and grade and type of structure in the lower part of the B horizon, and significant differences in clay, pH, available phosphorus, and total phosphorus depth distributions were found between group No. II and III soils and the group No. I and representative soils from east-central Iowa. On the basis of significant differences in morphological, physical, and chemical properties, the group No. II and III soils were considered more strongly developed than the group No. I and representative soils from east-central Iowa.

DOI

https://doi.org/10.31274/rtd-180813-11735

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Thomas James Bicki

Language

en

Proquest ID

AAI8123117

File Format

application/pdf

File Size

348 pages

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