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Title:A reassessment of the genesis of the Sangamon stone line and texture contrast profile in McDonough County, western Illinois
Author(s):Balek, Cynthia L.
Doctoral Committee Chair(s):Johnson, D.L.
Department / Program:Geography
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Biology, Ecology
Physical Geography
Abstract:This research reassesses the origin of the Sangamon stone line and texture contrast profile in a portion of western Illinois. Stone lines are commonly interpreted as former surface lags fanned by hillslope erosion owed to changes in environment, mainly climate. According to erosion models, texture contrast soils with stone lines are developed in two parent materials where the stone line separates an underlying, truncated, often fine-textured autochthonous subsoil from a younger, overlying coarse-textured allochthonous hillslope deposit. The hillslope deposit commonly possesses upper solum characteristics that are interpreted to have developed subsequent to the erosional event. As an alternative to the erosion hypothesis, some texture contrast stone line soils are interpreted to have formed biopedogenically in one parent material through the vertical sorting activity of soil fauna.
The purpose of the research was to test still another, equally if not more plausible hypothesis, that stone lines in Sangamon soils with texture contrast profiles formed due to "normal" suite of profile processes, a suite which includes biomechanical processes, such as subsurface burrowing and surface mound-building activity by animals. A biopedogeomorphic model is here proposed in which vertical biopedognic processes interact with "normal" landscape downwasting-upbuilding-and catenary processes to produce texture contrast stone line soils. The model was developed to explain the lateral consistency of the Sangamon Soil stone line profile across all nondepressional landscape positions in a portion of western Illinois.
Parts of two buried Sangamon Soil catenas drumlin-like landforms in McDonough County, western Illinois, were the focus of this work. Particle size analysis, pebble fabric analysis of stones in the stone line, micromorphology, light mineral analysis and fecal pellet analysis were conducted to ascertain parent material uniformity and the role of geomorphic versus biopedogenic processes in the formation of the paleocatenas. Results of the study indicate that the Sangamon Soil texture contrast-stone line profile is more likely to have been produced by "normal" biopedogenic processes than by purely erosion processes. The results also suggest that while both vertical and lateral biopedogeomorphic processes were important, the former were probably more so. It is further concluded that soil formation that produces stone-line bearing texture contrast profiles without episodic erosional truncation can be an on-going process in mid-latitude areas subjected to alternating climates.
Issue Date:1995
Rights Information:Copyright 1995 Balek, Cynthia L.
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9543522
OCLC Identifier:(UMI)AAI9543522

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