Geomorphology Commons^™

The Spatial And Temporal Distribution Of Large Rock Blocks And Control On Landscape Evolution In The Ozarks, Chelsea Moran

Graduate Theses and Dissertations

Geologists often use landscape form to infer landscape processes through time. While climate and tectonics shape geomorphic form, the potential range of spatial or temporal scales that can shape any specific landscape can render landscape process-form based hypotheses too general for consideration. Contributions by mathematical modeling have helped bridge the gap between inferring processes from form, notably in how sediment transport dynamics shape hillslopes. However, few models encapsulate the movement of large rock blocks ( >2 meters across) and their potential impact as hillslope sediment transport disruptors. The Upper Buffalo River watershed (BRW) in the Ozarks of northern Arkansas has …

A Comparison Of Relict And Active Terrestrial Patterned Ground As An Analog For Mars, John Paul Knightly Jr.

Graduate Theses and Dissertations

Patterned ground is a ubiquitous landform in periglacial regions of Earth and is also present across the mid to high latitudes of Mars. The association of terrestrial patterned ground to the presence of subsurface water ice in the form of permafrost that develops a seasonal ‘wet’ active layer during the summer thaw prompted further investigation of patterned ground on Mars. The Phoenix spacecraft was sent to the surface of the north polar plains of Mars to investigate an area of patterned ground where water ice was predicted to occur. The confirmation of subsurface water ice at the Phoenix landing site …

The Morphodynamic Interaction Of River Deltas And Their Marshes, Kelly M. Sanks

Graduate Theses and Dissertations

Globally, many of the largest river deltas contain vast marsh platforms that are currently threatened due to a combination of anthropogenic alterations to rivers and increasing relative sea level rise. Restoration and management plans for river deltas depend on optimizing riverine sediment accumulation in marsh platforms. However, the accumulation of organic material in marsh platforms is often neglected in predictive models and the interaction of ecogeomorphic processes governing marsh accumulation with the physical processes governing river delta growth is poorly understood.

Herein, I investigate this complex relationship through a combination of field and experimental studies. I show that in coastal …

Analysis Of Titan's Fluvial Features Using Numerical Modeling, Jeshurun Horton

Mechanical Engineering Undergraduate Honors Theses

River channels have been observed near the Huygens probe landing site on the surface of Titan, along with evidence of rounded water ice boulders transported through fluid flow. Evidence near the landing site suggests active flow of liquid methane, which has motivated the study of the effects of sediment load and channel sizes on Titan’s fluvial features. A numerical model is used to determine the viscosity, flow velocity, and critical boulder transport diameter based on channel size, slope, and a range of sediment concentrations. This model achieves two ends: first, observed boulder diameters are used to determine the ideal channel …

Modeling And Measuring Water Level Fluctuations In The Greenland Ice Sheet: How Moulin Life Cycle And Shape Can Inform Us On The Subglacial Drainage System., Celia Trunz

Graduate Theses and Dissertations

In the ablation zone of land terminating sectors of the Greenland Ice Sheet (GrIS), water pressures at the bed control ice motion variability on diurnal and seasonal timescales. During the melt season, large volumes of surface meltwater access the ice-bed interface through moulins.Moulins are large vertical shafts that connect the supraglacial and subglacial drainage systems. Moulins form when a crevasse intersects a surface meltwater source that can drive hydrofracture to the bed of the ice sheet. Upon reaching the bed, meltwater can establish and sustain an efficient, channelized drainage system. Due to the technical impossibility of physically exploring underwater passages …

Effects Of The Triassic-Jurassic Central Atlantic Magmatic Event Recorded In Continental Strata In Western Pangea: The Δ13c Record Of Warner Valley & Zion National Park, Dennis Mmasa

Graduate Theses and Dissertations

The Triassic is a period of abrupt climate change bracketed by mass extinctions including one driven by the eruption of the Central Atlantic Magmatic Province (CAMP) in the Late Triassic. The Moenave Formation (MF) of Utah and Arizona is ideal to investigate effects of the CAMP on continental strata distal to the eruptive center. This study focuses on the C-isotopic composition of bulk carbonate C from two localities, Blacks Canyon, Zion National Park, UT and Olsen Canyon within Warner Valley, UT. The data collected was used to document a chemostratigraphic record to compare to globally established records and bulk organic …

Exploring Sediment Compaction In Experimental Deltas: Towards A Meso-Scale Understanding Of Coastal Subsidence Patterns, Samuel Mason Zapp

Graduate Theses and Dissertations

Subsidence in low elevation coastal areas has been extensively researched through direct field measurement, numerical modelling, and stratigraphic reconstruction of ancient sediment deposits. Here I present the first investigation of subsidence due to sediment compaction and consolidation in two laboratory scale river delta experiments. Compactional subsidence rates have never been thoroughly quantified in the experimental setting, though this mechanism is found to be a primary creator of total relative sea level rise which will likely cause coastlines to retreat in the coming years. Spatial and temporal trends in subsidence rates in the experimental setting may elucidate behavior which cannot be …

Geospatial Analyses Of Seismic Hazards And Risk Perception In Libya, Somaia Suwihli

Graduate Theses and Dissertations

Libya is not considered a highly active seismic region. However, several earthquakes of magnitude >5.0 have occurred there. This dissertation analyzes the seismicity of Libya in order to better understand earthquake hazards, related geomorphic features, and the current evolution of Libyan perceptions of seismic risk. The first article developed a baseline of past and current seismic inventory in Libya, which represented an assessment of Libya seismic hazard by translating, analyzing, and compiling historical sources and archaeological data. This study shows that Libya has experienced earthquakes in varying degrees since ancient times. Through the spatial and temporal distribution of earthquakes from …

Environmental Influences On Tree-Driven Karst Bedrock Physical Weathering, Cole Robert Jimerson

Graduate Theses and Dissertations

The role of tree roots as stressors that contribute to physical weathering processes and thus soil generation remains an open question in critical zone science. While evidence suggests roots may be able to damage rock by accessing pre-existing fractures, where they can expand due to water uptake or generate forces on rock in response to wind gusts, these processes have not been investigated in temperate karst regions until now. I monitored forces at the root-rock interface for an American elm and Hackberry tree between September 2019 and May 2020. I used piezoelectric force sensors to determine if differences in species, …

Spatial Analysis Of Soil Creep Rates On Mount Sequoyah, Fayetteville Arkansas, Amy Suzanne Morris

Graduate Theses and Dissertations

Mount Sequoyah in Fayetteville, Arkansas, is a part of the Boston Mountains, which are considered a deeply dissected plateau. The area is prone to mass wasting, which is the general downslope movement of sediments, soils, and rock through different processes that cause instabilities along a hillslope, and in its soil and loose rubble mantle. For this study, we looked at soil creep, which is the small-scale movement of soil downhill because of gravity, wetting and drying cycles, and heating and cooling cycles.

By measuring the tilt of utility poles, we determined multiple causes of soil creep. The variables that are …

The Shelf To Basin Transition And Tectonostratigraphy Of The Atoka Formation (Lower Pennsylvanian) In The Arkoma Basin, Northwest Arkansas, Travis Gibson White

Graduate Theses and Dissertations

The east-to-west oriented Arkoma Basin is a peripheral foreland basin or depositional trough that developed during the Carboniferous Period. This formation covers an aerial extent of approximately 33,800 square miles and spans from west-central Arkansas into southeastern Oklahoma (McGilvery, Manger, and Zachry, 2016; Perry, 1995). The Atoka Formation, deposited during the early Pennsylvanian, is the largest Paleozoic formation by aerial extent in the state of Arkansas and is located within and comprises the bulk of Arkoma Basin sediments (McFarland, 2004; Nance, 2018). This formation has been informally divided into three divisions, the lower, middle, and upper, based on their stratigraphic …

The Structure And Dynamics Of A River Delta Are Related Through Its Nourishment Area, Suggesting Optimality, Christopher A. Cathcart

Graduate Theses and Dissertations

Scaling relations in tributary network geomorphology are well understood with respect to optimality. However, the scaling relations between structure and dynamics in distributary network geomorphology are less well understood. This is primarily due to the fact that nourishment area boundaries are difficult to map compared to tributary network catchment area boundaries. Furthermore, most previous work has focused either on the distributary channel networks or the delta’s partitioning of discharge. Here we show that, on the Wax Lake Delta (WLD) in Louisiana, the asymmetry in nourishment areas and downstream nourishment boundary width (∏) at a channel bifurcation, acts as a control …

Geochemical Analysis Of Mississippian Cherts And Devonian-Mississippian Novaculites, Southern Midcontinent Region, Julie Mary Cains

Graduate Theses and Dissertations

This study uses trace elements and radiogenic isotopes (Pb, Sr, and Nd) to investigate the origin and mode of formation for the siliceous deposits in the Lower Mississippian Boone Formation and the Devonian-Mississippian Arkansas Novaculite in the southern midcontinent. Mississippi Valley-type Pb-Zn ore deposits in the Tri-State District and the Northern Arkansas District were deposited by hydrothermal fluids, and highly radiogenic Pb isotope ratios suggest a genetic relationship between the Boone Formation chert (206Pb/204Pb ~ 21.59, 207Pb/204Pb ~ 15.87, 208Pb/204Pb ~ 40.10) and the MVT ores. Due to the very low concentration of Pb in the Boone chert (~2 ppm) …

Changes To Subaqueous Delta Bathymetry Following A High River Flow Event, Wax Lake Delta, Usa, Amanda Rose Whaling

Graduate Theses and Dissertations

I report changes to the subaqueous bathymetry of the Wax Lake Delta (WLD) located in coastal Louisiana with the purpose of quantifying the two- and three-dimensional evolution of the entire delta front. The spatial distribution and volume of erosion and deposition were determined by differencing two Digital Elevation Models (DEMs) collected 16 months apart, including the 2nd largest high flow event (flood) in the WLD’s recorded history. The difference map showed 6.41×10^6 m^3 ± 3.70% of sediment were deposited and 1.19×10^7 m^3 ± 2.71% were eroded yielding 5.46×10^6 m^3 ± 7.32% of net erosion in the survey area (~75.9 km^2). …

Speleogenesis In Turbulent Flow, Max P. Cooper

Graduate Theses and Dissertations

Existing models of speleogenesis neglect the shape of cross-sections, which can hold information related to climate, tectonics, and sediment supply in their widths. The first study of this dissertation simulates cross-sections of phreatic tubes, vadose canyons, and paragenetic galleries using a method developed for bedrock channels. Successful simulation of these cross-sections depends on erosion scaling with shear stress, in conflict with speleogenesis theory. Scaling of equilibrium width in paragenetic galleries was explored through analytical derivation and simulations, showing that width scales positively with discharge to the 1/2 power, and negatively with a weak power of sediment supply. Negative scaling of …

Keeping Pace With Relative Sea Level Rise: Marsh Platform Monitoring Shows Minimal Sediment Deficit Along The Louisiana Coast, Kelly Marie Sanks

Graduate Theses and Dissertations

Recent reports estimate that the marshes of the Mississippi Delta receive just 30% of the sediment necessary to sustain current land area1. An extensive monitoring campaign by the USGS and LCPRA provides direct measurements of sediment accumulation, subsidence rates, and deposit characteristics along the coast over the past 10 years2, allowing us to directly evaluate this sediment balance. By interpolating bulk density, organic fraction, and vertical accretion rates from 273 sites, a direct measurement of organic and inorganic sediment accumulation can be made. Results show that a total of 82 MT/year of sediment is delivered to the coast. Using a …

The Role Of Co2 Sublimation In Mass Wasting And Landscape Evolution Under Martian Conditions, Matthew Edwin Sylvest

Graduate Theses and Dissertations

Here we present the first set of laboratory experiments under martian atmospheric conditions which demonstrate that the sublimation of CO2 ice from within the sediment body can trigger failure of unconsolidated, regolith slopes, and can measurably alter the landscape. Previous theoretical studies required CO2 slab ice for movements, but we find that only frost is required. Hence, sediment transport by CO2 sublimation could be more widely applicable (in space and time) on Mars than previously thought. This supports recent work suggesting CO2 sublimation could be responsible for recent modification in martian gullies.

A second set of experiments were carried out …

3d Seismic Interpretation Of A Plio-Pleistocene Mass Transport Deposit In The Deepwater Taranaki Basin Of New Zealand, Francisco Jose Rusconi

Graduate Theses and Dissertations

A series of Plio-Pleistocene mass transport deposits (MTD) have been identified in the deepwater Taranaki Basin, in New Zealand, using the Romney 3D seismic survey, which covers an area of approximately 2000 km2. One of these MTDs has been chosen for description and interpretation based on high confidence mapping of its boundary surfaces. The deposit exhibits an array of interesting features similar to those documented by researchers elsewhere plus a unique basal feature unlike those previously observed. The basal shear surface exhibits erosional features such as grooves, “monkey fingers”, and glide tracks. Internally, the MTD is typically characterized by low …

Rock Art Management And Landscape Change: Mixed Field Assessment Techniques For Cultural Stone Decay, Kaelin M. Groom

Graduate Theses and Dissertations

As tourism continues to grow as one of the world’s most ubiquitous markets, the development and promotion of non-invasive techniques for cultural stone decay analysis and landscape change are vital to establishing conditional base-lines to best aid cultural heritage management (CRM) efficacy. Using rock art as a medium, this dissertation presents three independent case studies employing the Rock Art Stability Index (RASI) and repeat photography to explore the merits of mixed rapid field assessment techniques in relation to CRM and heritage tourism. While rock art is only one example of irreplaceable world heritage resources, examining how they decay and what …

Comparison Of Flow Dynamics And Bifurcation Angles In Tributary And Distributary Channel Networks, Thomas Coffey

Graduate Theses and Dissertations

The dynamics of channel mouth bifurcations on river deltas can be understood using theory developed in tributary channel networks. Bifurcations in groundwater-fed tributary networks have been shown to evolve dependent on diffusive ground water flow patterns

directly adjacent to the channel network, producing a critical angle of 72°. We test the hypothesis that bifurcation angles in distributary channel networks are likewise dictated by a diffusive external flow field, in this case the shallow surface water surrounding the subaqueous portion of distributary channels in a deltaic setting. We measured 25 unique distributary bifurcations in an experimental delta and 197 bifurcations in …

Statistical Analysis Of Fluvial Channel Belts, Kyle Ryan Spencer

Graduate Theses and Dissertations

As meandering rivers laterally migrate over time, they build channel belts. The accumulation of all previous flow paths creates the channel belt. To better understand these ancient rivers, modern river systems are being mapped to find statistical relationships between current flow path and the channel belt of river systems. It is important to examine a wide range of systems in terms of age, size, and location. The rivers are being mapped using an ImageJ, interpretations from Saucier (1994) and Google Earth. Three channel belt morphologies are mapped for 15 modern channel belts; the width of the river in relation to …

Influences Of Channel Dredging On Avulsion Potential At The Atchafalaya River, Gordon William Mccain

Graduate Theses and Dissertations

In 1950, the U.S. Army Corps of Engineers (USACE) reported a rapid increase of water discharge from the Mississippi River to its distributary channel; the Atchafalaya River. If not prevented by man-made structures, the complete capture of the Mississippi River by the Atchafalaya River was predicted. The USACE report cites multiple causes for the observed increase in discharge partitioning, yet fails to assess the largescale channel dredging operations conducted throughout the Atchafalaya River Basin during the 1930's and 1940's as a potential cause for the increased discharge. To assess the role man-made interventions, specifically channel dredging, played in the increase …

Reservoir Characterization And Depositional System Of The Atokan Grant Sand, Fort Worth Basin, Texas, Victoria Wood

Graduate Theses and Dissertations

The Atokan Grant Sands are a tight gas sand play that would add new reserves to the Fort Worth Basin. The Fort Worth Basin is located in north-central Texas just west of Dallas, Texas. Within the basin, the study area consists of Denton, Wise, Tarrant, and Parker Counties in Texas. The basin is bounded to the north by the Red River Arch, to the west by the Bend Arch, to the south by the Llano uplift, to the east by the Ouachita structural front, and to the northeast by the Muenster Arch. The Grant Sands are approximately 1,500 ft stratigraphically …

Lithologic Controls On Bedrock Channel Morphology In The Buffalo River Basin, Evan A. Thaler

Graduate Theses and Dissertations

The longevity of high relief terrains in passive margin systems remains an explained phenomenon in geomorphology. Current landscape evolution models assume an equilibrium state between rock uplift rates and erosion rates. However, analysis of chi gradients of bedrock channels across several lithologies in the Buffalo River Basin reveals disequilibrium in the basin controlled by the presence of a thick interval of Pennsylvanian sandstone that caps many of the plateaus in the basin. Headwater channels beneath the caprock tend to have higher chi gradient values in all lithologies than headwater channels in basins where the sandstone caprock is absent. High chi …

Controls On Dissolution Rate Variation At A Pair Of Underflow-Overflow Springs At The Savoy Experimental Watershed, Kiefer Allen Vaughn

Graduate Theses and Dissertations

Physical dissolution experiments and numerical modeling have been used in the past to study limestone dissolution rates. Numerical models have typically used constant dissolution rates, whereas rates in nature vary in time. Limestone tablets allow natural estimation of rates over month time scales, but these rates cannot necessarily be extrapolated to geologic timescales and also do not aid our understanding of short term variability. This study characterizes natural variability in these rates and examines potential causes of that variability from first principles. This may enable more accurate projections of dissolution rates within models. This study combines measurement of physical and …

Analysis Of Environmental Influences On Dressed Stone Decay: A Case Study Of Tafoni Development On A Hewn Djinn Block In Petra, Jordan, Kaelin M. Groom

Graduate Theses and Dissertations

Petra, Jordan captivates tourists and researchers with its dramatic sandstone cliffs, Nabatean, Roman, Byzantine and Roman architecture, and rich cultural heritage. However, increasing tourism in the valley is exacerbating stone degradation and complicating heritage management. This research analyzed environmental influences on dressed stone decay via tafoni development and evaluating cell evolution on an isolated hewn feature, known as Djinn Block X. Resembling other sandstone blocks found in the area, this irregular sandstone monument exhibits faces ranging in size from 2.5m by 3.5m to 3.9m to 4.2m (29m perimeter). Protruding features, incisions along the top, and a large platform attached to …

Breckenridge Shelter Geoarchaeology, Trevor John Seekamp

Graduate Theses and Dissertations

My graduate research mainly focuses on Breckenridge Shelter (3CR002), Carroll County, Arkansas. As a geoarchaeologist, my concerns are geomorphological and geological processes affecting the shelter and surrounding hill slope. Breckenridge is one of several similar, Pine Hollow bluff shelters, about Beaver Lake, an impoundment of the White River, in northwest Arkansas.

Classification Of Satellite Time Series-Derived Land Surface Phenology Focused On The Northern Fertile Crescent, Brian Embree Bunker

Graduate Theses and Dissertations

Land surface phenology describes events in a seasonal vegetation cycle and can be used in a variety of applications from predicting onset of future drought conditions, to revealing potential limits of historical dry farming, to guiding more accurate dating of archeological sites. Traditional methods of monitoring vegetation phenology use data collected in situ. However, vegetation health indices derived from satellite remote sensor data, such as the normalized difference vegetation index (NDVI), have been used as proxy for vegetation phenology due to their repeated acquisition and broad area coverage. Land surface phenology is accessible in the NDVI satellite record when images …

Penetration Forces For Subsurface Regolith Probes, Ahmed Elshafie

Graduate Theses and Dissertations

Investigating planetary bodies using penetrometers can provide detailed information about its history and evolution. An estimation of subsurface density and porosity can be made from the shape of the penetration curve. Using penetrometers mounted on planetary platforms could be challenging due to the uncertainty of the subsurface composition and since the maximum allowed force for penetration is the weight of the lander or rover on the surface. Estimation of penetration forces can provide a reliable constraint on the maximum reachable depth without endangering the whole mission. Therefore, knowledge of the required penetration force to specific depths can be helpful in …

Subsurface Planetary Investigation Techniques And Their Role For Assessing Subsurface Planetary Composition, Ahmed Elshafie

Graduate Theses and Dissertations

Subsurface planetary investigation techniques are of high interest and importance for the scientific community. Not only they can enhance our knowledge of the history of planetary formation but also can lead to information about its future. Whether the investigation is being conducted remotely using imagers, radars or physically using penetrometers or drills, a pre-existed knowledge of the mechanical and electrical properties of the subsurface regolith should be acquired for better data interpretation and analysis. Therefore, the main objective of this work is to investigate the mechanical and electrical properties of planetary analogs, understand their role for assessing the subsurface structure …