Geophysical investigation of the stone zone and loamy mantle on the Iowan surface
The processes that generated the distinctive landscape of the Iowa Erosion Surface (IES) of northeastern Iowa have been debated for over a century. A number of researchers have concluded that the IES experienced a periglacial environment and was underlain by continuous permafrost during the last gla...
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The University of Iowa
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ftproquest:oai:pqdtoai.proquest.com:1550914 2023-05-15T16:37:45+02:00 Geophysical investigation of the stone zone and loamy mantle on the Iowan surface Matzke, Jeffrey Alan 2013-01-01 00:00:01.0 http://pqdtopen.proquest.com/#viewpdf?dispub=1550914 ENG eng The University of Iowa http://pqdtopen.proquest.com/#viewpdf?dispub=1550914 Geology|Geophysics|Soil sciences thesis 2013 ftproquest 2021-03-13T17:36:23Z The processes that generated the distinctive landscape of the Iowa Erosion Surface (IES) of northeastern Iowa have been debated for over a century. A number of researchers have concluded that the IES experienced a periglacial environment and was underlain by continuous permafrost during the last glacial maximum. Ubiquitous throughout the IES is a stone zone that lies 60-100cm below the surface. Several explanations for the genesis of the stone zone have been proposed, including a lag concentrate, biomantle processes, and cryogenesis. We utilized a combination of coring and trenching, ground penetrating radar and resistivity to investigate the 3D distribution of the stone zone, overlying "pedisediment" and the underlying contact with dense till across a 100m2 area on a typical IES hillslope in east-central Iowa . Our preliminary results indicate that the stone zone occurs in the basal few decimeters of pedisediment that rests uncomformably and abruptly on eroded, dense till. Ice wedge casts extend from the stone zone into the underlying till. The depth of the stone zone below the modern surface increases downslope and the stone zone dissipates and eventually is replaced by relatively thick loamy sand beneath the footslope. These relationships argue against the stone zone being of biogenic origin. The occurrence of ice wedge casts associated with the stone zone and systematic changes in the thickness and texture of the pedisediment suggest to us that stone zone on the IES was formed by a combination of cryogenic and active zone erosive processes during the full glacial period. Thesis Ice permafrost wedge* PQDT Open: Open Access Dissertations and Theses (ProQuest) |
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PQDT Open: Open Access Dissertations and Theses (ProQuest) |
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ftproquest |
language |
English |
topic |
Geology|Geophysics|Soil sciences |
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Geology|Geophysics|Soil sciences Matzke, Jeffrey Alan Geophysical investigation of the stone zone and loamy mantle on the Iowan surface |
topic_facet |
Geology|Geophysics|Soil sciences |
description |
The processes that generated the distinctive landscape of the Iowa Erosion Surface (IES) of northeastern Iowa have been debated for over a century. A number of researchers have concluded that the IES experienced a periglacial environment and was underlain by continuous permafrost during the last glacial maximum. Ubiquitous throughout the IES is a stone zone that lies 60-100cm below the surface. Several explanations for the genesis of the stone zone have been proposed, including a lag concentrate, biomantle processes, and cryogenesis. We utilized a combination of coring and trenching, ground penetrating radar and resistivity to investigate the 3D distribution of the stone zone, overlying "pedisediment" and the underlying contact with dense till across a 100m2 area on a typical IES hillslope in east-central Iowa . Our preliminary results indicate that the stone zone occurs in the basal few decimeters of pedisediment that rests uncomformably and abruptly on eroded, dense till. Ice wedge casts extend from the stone zone into the underlying till. The depth of the stone zone below the modern surface increases downslope and the stone zone dissipates and eventually is replaced by relatively thick loamy sand beneath the footslope. These relationships argue against the stone zone being of biogenic origin. The occurrence of ice wedge casts associated with the stone zone and systematic changes in the thickness and texture of the pedisediment suggest to us that stone zone on the IES was formed by a combination of cryogenic and active zone erosive processes during the full glacial period. |
format |
Thesis |
author |
Matzke, Jeffrey Alan |
author_facet |
Matzke, Jeffrey Alan |
author_sort |
Matzke, Jeffrey Alan |
title |
Geophysical investigation of the stone zone and loamy mantle on the Iowan surface |
title_short |
Geophysical investigation of the stone zone and loamy mantle on the Iowan surface |
title_full |
Geophysical investigation of the stone zone and loamy mantle on the Iowan surface |
title_fullStr |
Geophysical investigation of the stone zone and loamy mantle on the Iowan surface |
title_full_unstemmed |
Geophysical investigation of the stone zone and loamy mantle on the Iowan surface |
title_sort |
geophysical investigation of the stone zone and loamy mantle on the iowan surface |
publisher |
The University of Iowa |
publishDate |
2013 |
url |
http://pqdtopen.proquest.com/#viewpdf?dispub=1550914 |
genre |
Ice permafrost wedge* |
genre_facet |
Ice permafrost wedge* |
op_relation |
http://pqdtopen.proquest.com/#viewpdf?dispub=1550914 |
_version_ |
1766028054430220288 |