Geomorphology Commons^™

The Fragmentation Of Helcar: A Paratethyan Model For Rhûn, Núrnen And The Dead Marshes, Federico Manzoni

Journal of Tolkien Research

This work proposes a conjectural paleogeographic model linking the Sea of Rhûn, Núrnen and the Dead Marshes to the former Sea of Helcar. Beginning from Christopher Tolkien's suggestion that Rhûn may represent Helcar ``vastly shrunken,'' the study combines textual evidence, the Ambarkanta, Fonstad's cartographic reconstructions, and terrestrial analogues drawn from the evolution of the Paratethys, the Messinian Salinity Crisis and other endorheic basins. Helcar is interpreted not merely as an isolated body of deep water but as the centre of a broader hydrological province subsequently partitioned by relief change, sedimentary infilling, basin isolation and drainage reorganization. Within this model, Rhûn …

Sedimentary Dynamics In Tubular Sandstone Caves, Porto União, Southern Brazil, Leandro Bianchini, Julio Cesar Paisani

International Journal of Speleology

Clastic sedimentation in sandstone caves remains poorly understood, particularly in systems with tubular morphology. This study investigates sedimentation, reworking, and sediment removal dynamics in the Legru Cave system, southern Brazil, based on the integrated analysis of sedimentary facies, microstructures, and microfeatures, combined with optically stimulated luminescence dating. The results indicate that conduit infilling is dominated by high-density flows, including cohesive debris flows, partially diluted multiphase flows, and flows with intermediate rheological behavior between mud flow and hyperconcentrated flow, in addition to shallow flow alternations. Sediment supply is predominantly allochthonous, related to hillslope-derived material delivered by overland flow and mud flows, …

Hydrogeophysical Assessment Of Groundwater And Saltwater–Freshwater Interface In A Quaternary– Neogene Coastal Aquifer, Kilwa Kisiwani Island, Southeast Tanzania, Simon R. Melchioly

Tanzania Journal of Science

This study aims to identify and explore new potential sites of groundwater resources using geophysical methods, and to demarcate the depth to the saltwater-freshwater interface. Kilwa Kisiwani Island is geologically covered mostly by Neogene and Quaternary alluvial sediments, sand and gravel. The geophysical techniques employed during the research include Vertical Electrical Sounding (VES), Electrical Resistivity Tomography (ERT), and Transient Electromagnetics (TEM). The Island has the potential for groundwater occurrences, but the layer with fresh water is shallow and thin. Out of the 18 VES sites, 2 (11%) points have shown non-potential, but the remaining 16 (89%) of the VES sites …

Understanding The Long-Term Patterns Of Change Of A Tidal Marsh In Mission Bay, San Diego, California, Carrie A. Shuster, Theresa Sinicrope Talley Ph.D., Drew Talley Ph.D., Zhi-Yong Yin Ph.D., Kellie Uyeda Ph.D.

Theses

Coastal marshes are among California’s most productive ecosystems and the most impacted, having been extensively modified by dredging, filling, and urban development. This thesis investigates over a century of change for a marsh in Northern Mission Bay, San Diego, California using ecological and spatial analyses.

Chapter 1 provides an overview of the environmental history and current land use of the Northern Mission Bay marsh, tracing changes from pre-contact Indigenous stewardship through colonial and modern urban development. It also introduces a restoration plant palette derived from historical and contemporary species occurrences, ecological functions, and documented cultural uses. By integrating ethnobotanical knowledge …

Process From Noise: Erosion Threshold Variability And The Morphology Of Gravel-Bed Rivers, Robert Paul Kostynick

Arts & Sciences Graduate Student Theses and Dissertations

Rivers are remarkably consistent as their geometry, width, depth, and slope change systematically downstream in response to differences in fluid discharge and sediment transport throughout a channel. Rivers move both water and sediment through terrains that depend on these downstream geometric adjustments influencing water quality, ecology, infrastructure, channel morphology, and landscape evolution at increasing timescales respectively. Rivers thus influence all aspects of life and define our spatial landscapes that shape boundaries, whether physical, politically, or socially. Nevertheless, a river is dynamic and does not adhere to human-defined boundaries, making it vital that we understand how these features change over time …

Wavelet-Based Multiscale Analysis Of Cave Co₂ Concentration In Response To Short-Term High-Intensity Tourism Activities: Spatiotemporal Heterogeneity And Lag Characteristics, Mingda Cao, Wenwen Song, Yan Zhang, Jie Zhang, Zhiqiang Yao

International Journal of Speleology

High-intensity tourism activities can cause a significant increase in cave air CO₂ concentration, thereby affecting the cave micro-environment and secondary carbonate deposition. During the 2023 National Day Golden Week, high-frequency continuous monitoring of cave air CO₂ partial pressure (PCO_2(A)) and visitor numbers was conducted in Dawang Cave, Anhui Province. Wavelet transform and cross-correlation analyses were used to reveal the multi-scale response characteristics of CO₂ concentration to tourism activities. The results show that: (1) PCO_2(A) exhibited clear diurnal variations (higher during the day, lower at night) and decreased spatially with enhanced ventilation, controlled jointly by …

Mono Gold: An Informal Account Of The Geology, Production, And History Of Mono County Gold And Silver Mining Districts, D. D. Trent

Eastern Sierra History Journal

Mono Gold explores the mining production, technology, and history of the Eastern Sierra, with a special focus on Mono County. Author Dee Trent, a geologist, spent decades visiting, researching, and photographing each of the mining operations discussed in this book-length monograph.

Crustal Structure Of The Vøring Plateau And Vøring Spur From Joint Refraction And Reflection Travel-Time Tomography, Anika Nawar Mayeesha

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

Crustal architecture of the Vøring Plateau and Vøring Spur in the mid-Norwegian continental margin remains debated because the geophysical data in the area do not uniquely constrain whether the crust is continental, oceanic, or transitional. This study reanalyzes wide-angle ocean-bottom seismometer data from Profile 11-03 across the Vøring passive continental margin using joint travel-time tomography of crustal refractions and Moho reflections. A total of 6,760 first-arrival picks and 542 PmP picks from sixteen instruments were inverted for P-wave velocity and reflector depth. Three starting models were inverted independently to test sensitivity to the initial crustal configuration. The first two used …

Assessing Spatial Distribution Of Plausible Earthquake-Triggered Landslides Relative To Ca. 1000 Ybp Earthquake On The Gales Creek Fault, Jacqueline Rheingans

University Honors Theses

Modern coseismic landslides cluster near the surface trace of the fault that ruptured, suggesting that clustering of paleolandslides may record information about paleoearthquakes. This study documents the pattern of prehistoric landslides near the Gales Creek Fault (GCF), northwest Oregon, to assess whether it reflects an independently known paleoearthquake. The GCF is located northwest of Portland through the Cascadia fore-arc basin where landslides are often triggered by intense rainfall during the wet season or potentially by seismic shaking on the megathrust or on crustal faults. In order to understand how a seismic event on the GCF will impact landslide distribution I …

How Quickly Do Eastern Floodplains Store Carbon? Quantifying Reference Carbon Flux On The Dead Diamond River, Jacob Schnell

Earth Sciences Undergraduate Senior Theses

Terrestrial Earth systems sequester an estimated 30% of annual anthropogenic CO2 emissions. The largest share is stored in global soils which collectively store more than 3 times the amount of carbon as the atmosphere. Floodplains and river systems, while covering only 5–8% of land area, store 20–30% of the global soil organic carbon (SOC), yet, the rate at which floodplains sequester carbon remains highly uncertain. Here I constrain floodplain carbon sequestration rates for a model northeastern river that has not been impacted by development or significant human activity. I calculate carbon stock using total organic carbon and derive carbon flux …

Hillslope Aspect And Other Potential Controlling Factors On The Spacing Of Periglacial Stone Stripes In Se Oregon, Blue Hansen

University Honors Theses

Stone stripes are a type of patterned landscape that can be polygenetic in origin, but in the High Lava Plains province are interpreted to be relict periglacial features based on similarities to active stone stripe formation in current periglacial settings. Periglacial stone stripes are hypothesized to form via frost process, including ice-driven cracking and soil heave which is dependent on temperature, long-term differences in temperature may contribute to differences in stone stripe patterns or density. Stone stripes in Oregon and Idaho have previously been studied using field techniques, but there is room for reexamination of temperature controls on hillslope density …

”Wet Floodplains” Protect Carbon Sequestration Hot Spots: How Carbon Sequestration Varies Across The Floodplain, Jacob Schnell, Joshua Landis, Jordan Fields, Carl Renshaw

Wetterhahn Science Symposium Posters

Carbon hot spots (peats) store 2̃0x more carbon, and at a faster rate than any other area on the Dead Diamond floodplain. The fluxes found in this study give us a reference template for how river restoration could proceed, including how current techniques might be actively mismanaging these hot spots.

Quantifying Co2 And Ch4 Fluxes In A Semi-Arid Floodplain: Assessing Spatial And Temporal Drivers, Miles E. Kelsey

Earth and Planetary Sciences ETDs

Rivers transport sediment and carbon across Earth’s surface, and their floodplains can store carbon over decades to millennia, making them important to terrestrial carbon management. While soil carbon can persist long term, it may be released as greenhouse gases through processes like methanogenesis and heterotrophic respiration. Environmental controls on these fluxes remain poorly constrained across floodplains in different climate and geomorphic setting, but especially in semi-arid systems where measurements are limited. To address this gap, we quantified CO₂ and CH₄ fluxes along the Middle Rio Grande (New Mexico, USA) using 227 chamber measurements collected May to November 2025 at three …

Marine Geophysical Studies Of Coupled Tectonic And Sedimentary Processes At Active Plate Boundaries, Sarah R. Rysanek

Earth and Planetary Sciences ETDs

Deep-sea and convergent margin sedimentary systems preserve critical records of tectonic and climatic processes that shape Earth’s surface. This dissertation investigates source-to-sink sediment routing and forearc deformation to better constrain the interplay between sedimentary and tectonic processes, through investigations of a deep-sea fan system, and the forearc geomorphology offshore Nicaragua. In the Gulf of Alaska, we integrate ultra-long-offset and regional multi-channel seismic reflection data, multi-resolution bathymetry, and plate reconstructions to remap the Baranof Fan system. Results show that the fan is larger than previously recognized and constructed by two primary depocenters linked to distinct glacial sediment pathways, with accommodation space …

A Gis Analysis Of The Relationship Between Ndvi Value, Slope, And Aspect Of The Terrain Of The Prairie Restoration Project, Basil Lund

2026 Symposium

The Prairie Restoration Project (PRP) encompasses 115 acres of land on the west side of the EWU campus. The goal of the PRP is to restore what was once a section of wheat farm back to its original Palouse prairie state. Here, I am using publicly available satellite data to examine some potential variables affecting the health of wheat plants planted in the years 2009 to 2017. I have used 4-band aerial imagery to create a map of NDVI values within the bounds of the PRP, which visualizes the near-infrared wavelengths that are reflected by healthy, chlorophyll-rich plants. I have …

Evaluating Improvements In Landslide Susceptibility Mapping Using Newly Derived Slope Units, Xinyi Zhang

Honors Capstones

Landslides frequently occur in mountainous regions and remain one of the major natural hazards threatening human safety, infrastructure, and regional development. In areas with steep terrain and intense rainfall, landslide disasters often cause serious economic losses and environmental damage. Landslide susceptibility mapping (LSM) has been widely used to identify potential landslide prone areas and to support disaster prevention, land management, and hazard mitigation. The accuracy of LSM is strongly influenced by the selection of mapping units.

This study focuses on I-lan County, Taiwan, and applies a newly derived slope unit dataset to evaluate its influence on landslide susceptibility mapping. Using …

Age And Characteristics Of Quaternary Fluvial And Dune Deposits Along The Arkansas And Cimarron Rivers In Osage And Pawnee Counties, Oklahoma, Barry A. Duncan

Graduate Theses and Dissertations

Quaternary aeolian and fluvial deposits along the Arkansas and Cimarron Rivers in Osage and Pawnee counties of central Oklahoma, record Late Pleistocene and Holocene fluvial landscape history in the eastern Osage Plains. Sediment supply, climate variability, channel incision, and channel migration control this landscape evolution. Sediment supply of both streams is dominantly sand. Late Pleistocene and Holocene precipitation have varied with periods of drought alternating with increased precipitation and warming. The study area is near the eastern boundary of substantial aeolian activity with drought and aeolian reworking of fluvial sand more severe to the west. This study examines the sediment, …

Of Dunes And Ice: A Surface-Atmosphere Investigation Of Mars Co2 Sublimation Features And Titan Aeolian Fields, Racine D. Cleveland

Graduate Theses and Dissertations

This dissertation investigates a central question: How do planetary boundary layer processes manifest in observable surface geomorphology, and how can planetary imagery be used to quantify those effects? The planetary boundary layer (PBL) governs near-surface exchanges of momentum, heat, and volatiles, yet direct atmospheric measurements remain spatially and temporally limited on most planetary bodies. By analyzing geomorphic features preserved in high-resolution imagery, this work quantifies how boundary-layer processes leave measurable signatures on planetary surfaces. For Mars, high-resolution images from the Mars Reconnaissance Orbiter (MRO) HiRISE instrument were used to map CO2 sublimation features, or Swiss Cheese Features (SCFs), on the …

Exploring Alternate Methods Of Flood Output Estimation During Natural Disasters, Finley Gardner

Honors College Theses

In April of 2025, extreme flooding damaged many homes and buildings of people across Kentucky. The Federal Emergency Management Agency (FEMA) produces maps that show the potential for flooding in areas around water bodies, but many of the April flooding damaged areas were well outside of the FEMA classification zones. The main purpose of this thesis research was to create an accurate model of potential flood extent in Kentucky and compare it to FEMA maps. This model did not require extensive computing power and produced a map that accurately depicted flood extent through the use of Digital Elevation Model (DEM) …

Recent Wetland Elevation Dynamics In Coastal Louisiana, Usa, Elizabeth Harris

LSU Master's Theses

Coastal marshes globally are increasingly vulnerable to accelerating relative sea-level rise (RSLR), which threatens their capacity to maintain elevation through feedbacks among sediment supply, vegetation productivity, hydrology, and soil processes. Although many marshes can persist under moderate rates of sea-level rise through vertical accretion and belowground biomass production, this resilience is strongly constrained by sediment availability and subsurface processes such as autocompaction and organic matter decomposition. High accretion is often assumed to confer marsh resilience; however, subsurface processes, particularly autocompaction driven by surface loading, can substantially offset elevation gains. Coastal Louisiana experiences among the highest rates of RSLR worldwide due …