Geology Commons^™

Evolution Of Propagator Wakes On The Kolbeinsey Ridge From An Integrated Geophysical Perspective, Ethan Stowell

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Oceanic lithosphere is formed following the extension and rifting of a continent, with new material generated at mid-ocean ridges. While ridges generally spread in the direction of extension, individual spreading centers are offset by perpendicular transform faults that break the ridges into individual segments. Ridge propagation, in which one ridge segment grows at the expense of another’s shortening, has been identified in global investigations as a poorly understood component of axial reorganization. This process leaves propagator wake structures composed of faults and pseudofaults visible as lows in Earth’s gravitational field, and transferred lithosphere with a distorted magnetic signature. This study …

Reconstructing Nebraska’S Late Quaternary Paleoenvironment, Landscape Change, And Human–Environment Dynamics Using Diatoms And Optically Stimulated Luminescence Dating, Gosia Mahoney

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This dissertation examines Holocene environmental change and human–environment interactions in the Nebraska Sand Hills by integrating geomorphic, paleoenvironmental, and geochronological data. It presents three complementary studies that together explore how climatic variability, local landscape processes, and human activity influenced environmental systems.

The first study reconstructs the early Holocene evolution of a dune-dammed valley in the central Sand Hills. Stratigraphic, sedimentological, and diatom evidence indicate that eolian activity resulted in a blocked fluvial system, leading to elevated groundwater levels and the formation of a wetland that later developed into a lake. Notably, this transformation occurred under relatively dry conditions, demonstrating that …

Nebraska Statewide Groundwater-Level Monitoring Report 2025, Aaron R. Young, Mark E. Burbach, Sue Olafsen Lackey, Robert Matthew Joeckel, Jeffrey Westrop

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Fulbright Project In Iceland In The Summer Of 2026, Irina Filina

Nebraska Academy of Sciences: Programs and Proceedings

This upcoming Fulbright project is inspired by an ongoing debate in the scientific community about the tectonic origin of Iceland. A long-standing theory of Iceland’s formation by excessive magmatism at the Mid-Atlantic spreading center over the well-known hot spot (i.e., oceanic crustal affinity) was recently challenged by the alternative hypothesis that the Icelandic crust is continental in nature and is being stretched and gradually modified by magmatic processes. Based on this hypothesis, a new sunken continent, Icelandia, has been proposed. One of the foundations for the proposed Icelandia is the presence of felsic lavas (indicative of continental flavor in the …

Last Glacial Maximum And Late Glacial Aeolian Sand Activity, South-Central Indiana, Usa, H. M. Loope, J. L. Antinao, P.R. Hanson, P. M. Jacobs, D. A. Grimley

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Report 17—Revisions To The Articles Of Organization And Procedure Of The Commission On Stratigraphic Nomenclature Of The Americas, Lynn T. Dafoe, Robert B. Macnaughton, Marie-Perre Aubry, Carlton E. Brett, James R. Lehane, Fernando Núñez-Useche, Randall C. Orndorff, Frank Brunton, Lucy E. Edwards, Richard H. Fluegeman, Howard Harper, Robert Matthew Joeckel, Norman P. Lasca, B. H. Tew

Conservation and Survey Division: Faculty and Staff Publications

Several revisions to the Articles of Organization and Procedure for the North American Commission on Stratigraphic Nomenclature have been adopted following the 75th, 79th, and 80th annual meetings of the Commission in 2020, 2024 and 2025, respectively. Of these, the most substantial change was revision of Article III regarding membership composition of the Commission and the addition of new member organizations from Central and South America and the Caribbean region. As a result, the Commission also voted to change its name to be more inclusive of the expanding membership, with approval of the name: Commission on Stratigraphic Nomenclature of the …

Understanding How Erosion And Unit Thickness Alter The Deformation Of Fold-Thrust Belts, Kaitlyn E. Gallis, Caroline M. Burberry

Nebraska Academy of Sciences: Programs and Proceedings

When a collision of two tectonic plates occurs, fold thrust belts develop, which are widely recognized as the most common mode in which the crust accommodates shortening. Most analog models do not consider erosion when documenting fold thrust belt formation. The lack of experiments on this topic means there are limited consistent studies on the relationship between erosion and deformation. Preliminary experiments suggest that the typical forward breaking thrust sequence is altered by eroding the hinterland, something this experiment series aims to prove or disprove. The new contribution of this work is a systematic evaluation of the variation in initial …

Modeling The Greenland-Iceland-Faroe Ridge Using Integrated Geophysical Analysis, Zachary Clowdus

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The Greenland-Iceland-Faroe Ridge (GIFR) is an area of significant geologic interest with anomalously thick crust related to enhanced melt generation from the interaction between the Mid-Atlantic Ridge and the Iceland hotspot. To the northeast of Iceland lies the Jan Mayen Microcontinent (JMMC), which is a continental fragment separated from Greenland during the opening of the Northern Atlantic. The overall extent of the JMMC, especially its southern boundary, remains poorly constrained. The crust beneath the GIFR is believed to be primarily of oceanic affinity. However, a recent discovery of felsic lavas in Iceland led to an alternative hypothesis that implies the …

Stable Isotope Paleoecology In The Bridgerian (Early Eocene): Investigation Of The Bridgerian Crash And The Canopy Effect, Aaron M. English

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The Early Eocene Climatic Optimum (EECO) was the warmest sustained interval of the Cenozoic. Its waning stages coincided with a marked decline in mammalian biodiversity known as the Bridgerian Crash, which was likely driven by increasingly cooler and drier conditions. Paleobotanical evidence suggests the early Eocene supported wet, subtropical to tropical forests at mid-latitudes, however the structure of these forests at the close of the EECO remains poorly understood. In this study, I measure carbon isotope values (d¹³C_E) from the enamel of early Bridgerian (~52.2 – 48.3 Ma) herbivorous mammals from the Greater Green River …

Groundwater In Nebraska, Troy E. Gilmore, Jesse T. Korus Dr.

Conservation and Survey Division: Faculty and Staff Publications

What is groundwater? Groundwater is water that fills and moves between spaces in underground rocks, gravel, sand, or other materials.

Older Groundwater Reservoirs In Nebraska, Marvin P. Carlson, Steven S. Sibray

Conservation and Survey Division: Faculty and Staff Publications

Sedimentary rocks below Nebraska's regional water table are saturated down to the crystalline igneous and metamorphic rocks of Precambrian age. The total thickness of these sedimentary rocks ranges from about 600 feet to over 10,000 feet. Nearly all current wells in Nebraska produce water from the near-surface, unconsolidated or partly consolidated rocks. Most studies to date -- interpretive reports, test drilling, inventory of wells, monitoring water levels, and water quality determinations -- have concentrated on these near-surface sources of groundwater.

Integrated Geophysical Modeling Of Newly Identified Pseudofaults Within Southern Cascadia Subduction Zone, Morgan R. Madsen

Honors Program: Senior Projects (Public)

The Cascadia Subduction Zone, located off the western coast of North America, has a long history of seismic activity, causing various geohazards such as megathrust earthquakes and tsunamis for the coastal population (Goldfinger et al., 2000; Tréhu et al., 2022). It is necessary to identify areas of greater risk, as seismic hazards will continue to affect the area due to ongoing subduction of the oceanic Juan de Fuca plate beneath the North American continent. Heavily fractured, weakened zones of oceanic crust, known as propagator wakes and pseudofaults, have been shown to correlate with greater seismicity (Ashraf and Filina, 2023a). Propagator …

Diffendal Receives Wisherd Award For University Service, Ronica Stromberg

Robert F. Diffendal, Jr., Publications

Even though he’s retired, Robert Diffendal seems to be working everywhere.

The professor emeritus in the School of Natural Resources retains offices in three buildings. He reports to work at the Center for Great Plains Studies five days a week for about four hours a day. His list of volunteer activities around the state goes on and on, affecting, by his count, 21,088 people since 2003, when he stepped away from full-time faculty work. He capped 2024 at Nebraska Innovation Campus, where he received the Wisherd Award for Outstanding Service to the University of Nebraska–Lincoln.

Chosen by the Emeriti and …

Stratigraphy And Osl Chronology Of Lunette Deposits Indicates That Nebraska’S Rainwater Basins Formed By Aeolian Deflation Between 39 And 25 Ka, P.R. Hanson, Robert Matthew Joeckel

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Early Holocene Interaction Of Aeolian, Alluvial, And Lacustrine Processes In A Dune-Dammed Valley In The Central Nebraska Sand Hills, Gpsia Mahoney, R. D. Mandel, P.R. Hanson, Sherilyn Fritz

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Conservation And Survey Division 2024 Annual Report, R.M. Joeckel, Michele Waszgis

Conservation and Survey Division: Faculty and Staff Publications

The Conservation and Survey Division of the University of Nebraska - Lincoln is the agency designated by statute to investigate and interpret the geologically related natural resources of the State, to make available to the public the results of these investigations, and to assist in the development and conservation of these resources. It consists of program areas in geology, water, soils and remote sensing-geographic information systems.

Exploring Intraplate Seismicity In The Midwest, Alexa Fernández

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Intraplate seismicity represents a notable occurrence within the stable North American Craton. This research explores the potential sources of stresses that could reactivate older faults and influence seismic activity within this region. Among these sources, the enduring impact of the last glacial period is considered, which includes continued glacial isostatic adjustments (GIA). During GIA the lithosphere rebounds due to the retreating ice, and the forebulge caused by far-field flexure in response to the glacial load, collapses. This results in significant faulting, fracturing, and seismic activity associated with the deglaciation phase. The adjustment of the lithosphere manifests as both near surface …

Sensitivity Of Present And Future Seasonal Precipitation Over Central United States To The Representation Of Rocky Mountain Topography, Ranasinghe Disanayakalage Sherly Shelton Ranathunga

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Precipitation change across the Central United States (USA) is of great interest to the research community. Studies using global climate simulations suggest that the “100^th-Meridian”, which separates the “dry west” from the “moist east” will shift to the east as the climate responds to future emissions pathways. However, these simulations are run at relatively coarse resolutions, which do not accurately represent topography. Here, we perform regional simulations using the Weather Research and Forecasting (WRF) model to explore the sensitivity of present and future precipitation patterns across the central USA to the representation of the Rocky Mountains (RM). We …

Phylogenetic And Biogeographic Patterns Of Devonian Proetid Trilobites, Katherine Jane Jordan

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Ecological disruption events such as mass extinctions can result in the permanent alteration in clades and ecosystems. A pivotal time of change during the history of life on Earth can be seen in the Devonian Period. During this time, major transitions in marine and terrestrial system resulted in a different world at the end of the period in comparison to the beginning. One such group most heavily impacted were trilobites. Trilobites were reduced to one order by the end of the Devonian: Proetida. My dissertation focuses on phylogenetic, biogeographic, and paleocommunity patterns of this group, known as the last of …

Theory Of An Automatic Seepage Meter And Ramifications For Applications, V. A. Zlotnik, D. K. Solomon, D. P. Genereux, T. E. Gilmore, C. E. Humphrey, A. R. Mittelstet, A. V. Zlotnik

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Public Horticulture: Process And Design Of The Lincoln Botanical Garden, Brad Kindler

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Beginning in 2012, the local non-profit, The Lincoln Botanical Garden, began organizing the conceptual design and creation of a glass conservatory within a botanical garden in Lincoln, Nebraska. These proposed urban enhancements seek to fill a gap in garden amenities in the city by providing year-round access to public horticulture programming and education.

This project, Public Horticulture: Process and Design of the Lincoln Botanical Garden, documents these efforts and makes design recommendations for a themed Glacial Erratic Garden that could be constructed within the botanical garden.

Advisors: Ellen Paparozzi and Sam Wortman

Publications And Other Works By R. F. Diffendal, Jr., Robert F. Diffendal Jr.

School of Natural Resources: Faculty Publications

Articles
Chapters in Books
Books
Field Guides
Geologic Maps
Other Maps
Cover Photographs
Other Photographs
Newspaper and Other Articles
Test-Hole Logs
Television Programs
Geonotes
Abstracts
Reviews
Manuscripts Accepted (A), Submitted (S), or in Preparation (P)
Geologic Maps in Press
Geologic Maps-Nebraska
Public Documents
Miscellaneous Publications
Editing

Updated March 2024

Stage And Discharge Prediction From Documentary Time-Lapse Imagery, Kenneth W. Chapman, Troy E. Gilmore, Mehrube Mehrubeoglu, Christian D. Chapman, Aaron R. Mittelstet, John E. Stranzl Jr.

Conservation and Survey Division: Faculty and Staff Publications

Imagery from fixed, ground-based cameras is rich in qualitative and quantitative information that can improve stream discharge monitoring. For instance, time-lapse imagery may be valuable for filling data gaps when sensors fail and/or during lapses in funding for monitoring programs. In this study, we used a large image archive (>40,000 images from 2012 to 2019) from a fixed, ground-based camera that is part of a documentary watershed imaging project (https://plattebasintimelapse.com/). Scalar image features were extracted from daylight images taken at one-hour intervals. The image features were fused with United States Geological Survey stage and discharge data as response variables …

Analysis Of Legacy Gravity Data Reveals Sediment-Filled Troughs Buried Under Flathead Valley, Montana, Usa, Ali Gebril, Mohamed A. Khalil, Robert Matthew Joeckel, James Rose

Conservation and Survey Division: Faculty and Staff Publications

Shallow, dominantly silt- and clay-filled erosional troughs in Quaternary sediments under the Flathead Valley (northwestern Montana, USA) are very likely to be hydraulic barriers limiting the horizontal flow of groundwater. Accurately mapping them is important because of increasing demand for groundwater.We used a legacy Bouguer gravity map measured in 1968. The directional derivatives of the map are computed, and the map was enhanced by implementing edge detection tools.We produced generalized derivative, maximum horizontal gradient, total gradient and tilt gradient maps through two-dimensional Fourier transform analysis. These maps were remarkably successful in locating buried troughs in the northern and northwestern parts …

Joint Interpretation Of Ert And Self-Potential Data To Characterize The Subsurface Geology And Hydrodynamics Along The Sutherland Supply Canal And Paxton Siphon Inlet, Paxton, Nebraska., M. K. Aboushanab, D. R. Hallum, R. M. Joeckel

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Migrating Whooping Crane Activity Near U.S. Air Force Bases And Airfields In Oklahoma, David A. Brandt, Aaron T. Pearse, Mark T. Bidwell, John Conkin, Matthew Butler

United States Geological Survey: Publications

The Aransas-Wood Buffalo population of Grus americana (Linnaeus, 1758; whooping cranes) migrates through the United States Great Plains, encountering places substantially altered by human activity. Using telemetry data from 2017 to 2022, we investigated whooping crane migration behavior around U.S. Air Force bases in Oklahoma. Our study focused on potential collision risks between whooping cranes and aircraft, a substantial concern for aviation safety. We determined that activity was greatest at Kegelman Air Force Auxiliary Airfield, near whooping crane critical habitat. On average, 61 percent of marked whooping cranes used locations west of Kegelman Air Force Auxiliary Airfield and Vance Air …

Leveraging High Resolution Classifications And Random Forests For Hindcasting Decades Of Mesic Ecosystem Dynamics In The Landsat Time Series, N. E. Kolarik, Nawaraj Shrestha, T. Caughlin, J. S. Brandt

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Nebraska Statewide Groundwater-Level Monitoring Report 2023, Aaron R. Young, Mark E. Burbach, Sue Olafsen Lackey, Robert Matthew Joeckel, Nawaraj Shrestha, Jeffrey Westrop

Conservation and Survey Division: Faculty and Staff Publications

This report is a synthesis of groundwater-level monitoring programs in Nebraska. It is a continuation of the series of annual reports and maps produced by the Conservation and Survey Division (CSD) of the University of Nebraska in cooperation with the U.S. Geological Survey (USGS) since the 1950s. Groundwater-level monitoring began in Nebraska in 1930 to survey the state’s groundwater resources and observe changes in its availability on a regular basis. The CSD and USGS cooperatively developed, maintained, and operated an observation-well network throughout the state. These two agencies were responsible for collecting and archiving this information, and for making it …

Transient Electromagnetic (Tem) Survey For Targeted Drilling On The Kurtzhals Property, Cedar County, Nebraska, Jesse Korus, Katherine (Katie) Cameron, Michele Waszgis

Conservation and Survey Division: Faculty and Staff Publications

The Kurtzhals property is in Section 19, Township 30N, Range 3 in Cedar County, Nebraska. The present land use is agricultural row crop, but past use included hog production. Two active irrigation wells are located on adjacent properties to the west and southwest. An irrigation well was installed in the northwest corner of the property in 2022. Due to the low yield (300 gallons per minute) of this well, Mr. Kurtzhals seeks to install an additional irrigation well to supplement the first. Several unsuccessful test holes had been drilled prior to the present survey. The purpose of this survey was …

Zircon Luminescence Dating Re-Visited, C. Schmidt, T. Halter, P.R. Hanson, A. Ulianov, B. Putlitz, G. E. King, S. Kreutzer

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.