Master of Science, Miami University, 2023, Geology and Environmental Earth Science

Fluvial terraces are vital to reconstructing past depositional dynamics within a watershed as well as determining flood and erosion risk. In the midwestern US, detailed mapping of terrace age is necessary to determine if deposition occurred during multiple distinct periods. In this study, changes to soil geochemistry over time were quantified from nine radiocarbon-dated soils spanning ~17,000 years and this relationship was used to infer soil age across a broad fluvial terrace. Regression models quantifying Fe/Ca, Zr/Ca, and Ti/Ca changes at multiple soil depths were created. Fe/Ca models returned R2 values between 0.69 and 0.97 with the lowest uncertainties compared to Zr/Ca and Ti/Ca models. Samples collected at 20-30 cm depth resulted in the highest correlation coefficient compared to samples collected at 0-10 and 60-70 cm. The mean Fe/Ca value of parent material was 0.33 with standard deviation 0.12. The models were subsequently used to infer soil age from Fe/Ca values of 388 locations on the floodplain and overbank deposits were delineated based on inferred soil age. In general, deposit age increases with increasing distance from the modern channel. Results support use of this field-based technique to map fluvial terraces at a high resolution.

Committee: Jason Rech Dr. (Advisor); Maija Sipola Dr. (Committee Member); Claire McLeod Dr. (Committee Member) Subjects: Earth; Geology; Geomorphology; Soil Sciences

PhD, University of Cincinnati, 2017, Arts and Sciences: Geology

Models attempting to define the links among climate, tectonics, erosion, and topography in high mountain environments have continued to evolve in recent years. Quantitative studies of the rates of catchment and bedrock erosion and the ages of significant depositional or erosional events are still needed to illuminate these complex links and their positive and negative feedbacks. Underlying climatic and tectonic forcings may exert significant control on the interplay of surface and tectonic processes and how mountain landscape systems develop. Regional variability poses an additional challenge to researchers in environments that are already dynamic and complex. To investigate how the interplay of these tectonic and climatic factors affect arid, mountainous regions and how they have affected the evolution of landscapes in mountain systems during the Quaternary, I present quantitative data bearing on the ages of moraines, strath and fluvial terraces, and alluvial fan surfaces using 10Be terrestrial cosmogenic nuclide (TCN) methods in the Pamir Range of western China and the Precordillera of Argentina, where optically-stimulated luminescence (OSL) dating was also applied. 10Be TCN methods were also used to determine catchment and bedrock erosion rates for a part of the Zanskar Range in the Indian Himalaya. My study examines the ages of these landforms within the context of each field area's climatic and tectonic setting. Dating and erosion results were analyzed within their geologic context, building a whole-basin sedimentary history in China, a regional climatic framework in Argentina, and a line between erosion rates and basin morphology and tectonics in India. In the Pamir Himalaya, results illustrate the presence of remarkably well-preserved alluvial fan surfaces dating back to ~580 ka, despite evidence of significant Quaternary basin change, including the development and drainage of a large paleolake and multiple glaciations since >80 ka. In the Zanskar (open full item for complete abstract)

Committee: Lewis Owen Ph.D. (Committee Chair); Marc Caffee Ph.D. (Committee Member); Craig Dietsch Ph.D. (Committee Member); Thomas Rockwell Ph.D. (Committee Member); Lindsay Schoenbohm Ph.D. (Committee Member) Subjects: Geology

Master of Science, University of Akron, 2016, Geology

The goal of this study was to determine the relative contributions of increased flood frequency and continued land development on geomorphic change and damage to infrastructure throughout the Yellow Creek, OH watershed. Comprised of five sub-watersheds, the Yellow Creek watershed is located in Northeast Ohio and is a tributary of the Cuyahoga River. In Northeast Ohio, a statistically significant change point in both heavy precipitation and stream flow occurred in July 2003. On the USGS Cuyahoga River Old Portage stream gage record, there were only 18 days of mean daily discharge above the top 1% flood category (76 m3s-1) during the 13 years prior to July 2003 compared to 79 days in the 13 years after July 2003. Land cover data reveals that impervious cover in the watershed has increased by 0.80% from 1985-1996, 0.32% from 1996-2001, 0.67% from 2001-2006, and 0.38% from 2006-2010. The five sub-watersheds have contrasting development histories and vary from 4.5% to 23.5% imperviousness. Water level loggers were installed to measure hydrograph variability between the five sub-watersheds. Water samples were also taken on 11/10/15, 2/3/16, and 2/24/16 in the five sub-watershed streams to find the effect development has on road salt concentration in the stream. Aerial photos for nine years between 1994 and 2015 were used to assess changes in stream geomorphology through time. Results show that geomorphic change has been greater after July 2003 compared to before July 2003. These post-2003 geomorphic changes include an increase in unvegetated mid-channel bars and point bars as well as amplified channel migration. Elsewhere, Yellow Creek shows straightening and widening in response to increased flooding events. The 2000 to 2005 and 2012 to 2015 photo intervals showed the largest geomorphic change throughout the Yellow Creek watershed, especially in areas with steep topography and stream slope. Although urbanization in the watershed results in increased runoff, since 2003 in (open full item for complete abstract)

Committee: John Peck (Advisor); Linda Barrett (Committee Member); John Senko (Committee Member) Subjects: Geomorphology; Hydrology

Master of Science, The Ohio State University, 2006, Graduate School

Committee: Not Provided (Other) Subjects:

MS, Kent State University, 2024, College of Arts and Sciences / Department of Earth Sciences

Anthropogenic macro debris, otherwise known as trash, in urban streams is a persistent environmental problem throughout the world. The factors influencing trash accumulation within US urban stream channels has not been thoroughly investigated, with previous studies focusing largely on surrounding land use. I hypothesized that fluvial geomorphology is a better predictor of trash concentration than GIS-derived variables and that increased geomorphic complexity of stream reaches is associated with higher trash concentrations in urban streams. To test these hypotheses, I examined the relationships between in-stream trash concentrations and different geomorphologic characteristics, catchment characteristics, and catchment and riparian land cover in Cleveland (Ohio) and Charlotte (North Carolina) streams. I collected data on trash (>5 cm), large wood, cross-section and longitudinal profiles, and sediment sizes in 24 urban stream reaches, and calculated 19 geomorphic complexity metrics. Catchment characteristics and land cover variables were derived using ArcGIS Pro. Single and multiple regression approach have been used to find relationships between trash concentration and predictor variables. Trash concentrations ranged from 0.18 to 4.7 pieces/m bankfull width, with an average of 1.55 pieces/m. 71.8% of the collected trash was plastic. More variation in trash concentrations across stream reaches was explained through geomorphologic variables as compared to GIS variables when city-specific multiple linear regression models were made. When data from the two cities were combined, the opposite was true. Cross-section characteristics, especially bankfull width, were amongst the strongest predictors of trash concentration in both cities. Longitudinal profile and sediment characteristics were not predictive of trash concentration for Cleveland streams, and these data were not collected in Charlotte. Therefore, my hypothesis that more trash will be found in streams with more geo (open full item for complete abstract)

Committee: Timothy Gallagher (Advisor); Anne Jefferson (Committee Member); Christie Bahlai (Committee Member) Subjects: Geomorphology; Hydrology; Water Resource Management

Master of Science, University of Toledo, 2023, Geology

Glacial Lake Agassiz is a paleolake that formed over central North America at the end of the last Ice Age at ~14.3 ka, and its drainage into the North Atlantic likely contributed to the Younger Dryas cooling at ~12,900–11,700 cal yr BP. Drainage events are identified through the chronologic and geomorphic analyses of strandlines, including beach ridges, escarpments, and spits, which record past lake levels. Strandlines in a study area in the southern basin of Lake Agassiz in NW Minnesota warp upward toward the north as a result of glacioisostatic adjustment (GIA). Older strandlines have a steeper north-south gradient than younger strandlines due to differential rates of rebound. The study area contains a series of strandlines that are classified into 11 strandline groups (SGs) rather than named beach ridges previously identified along other sections of the Lake Agassiz coastline. SGs are composed of one or two well-developed beach ridges, or sets of ridges, that branch out and increase in number toward the south, representing many minor drops in lake level up to ~3 m due to a combination of incision of the southern outlet and uplift caused by GIA. A beach ridge formation model developed from littoral sediment sample analyses and GPR data at 100–500 MHz frequencies suggest that strandlines in the study area formed in an overall depositional regressive system with intermittent storm events. The estimated beach ridge rate of formation is ~8.5-17 yrs/ridge based on ~70 Lockhart Phase beach ridges in the study area and the corresponding optically stimulated luminescence (OSL) dates for the Herman through Tintah beaches and meltwater signatures during drainage events. Strandline chronology is also assessed based on eight OSL dating samples. Most of the dates fell within the error margin for published dates from associated strandlines at the southern outlet. However, samples from the Campbell and Tintah beaches are approximately 3,000 years older t (open full item for complete abstract)

Committee: Timothy Fisher (Committee Chair); Richard Becker (Committee Member); Harry Jol (Committee Member) Subjects: Geology; Geomorphology

Master of Science (MS), Ohio University, 2023, Geological Sciences (Arts and Sciences)

Each cave is unique from structural or hydrological perspectives, which often complicates the prediction of subsurface flow routes needed for planning the economic development of karst landscapes and responding to groundwater contamination. This is true of the Great Savannah Cave System (GSCS) in southeastern West Virginia since the growing city of Lewisburg is expanding northward over the 50-mile-long cave system. The GSCS is the sixth-longest cave in the United States and pollution is affecting the cave in many still poorly defined ways. We report findings of a geological study of critical passages in GSCS as these findings to relate to subsurface flow paths and the prediction of unknown pathways. McClung Cave is in Greenbrier County in which the primary lithology is a Mississippian-age formation containing limestone and minor shales with negligible amounts of sandstone. Karst features of the GSCS formed along the contact zone between the Greenbrier and an underlying shale where streams sink upon encountering the limestones. Dip- and strike-oriented flow routes are analyzed using structural contouring, structural mapping, and passage morphologies. Vadose infeeders are generally oriented downdip, but with significant variability and hard-to-predict meandering due to geological features too small to be resolved in general geological mapping. Strike-oriented collector passages receive vadose streams from updip but are epiphreatic with infrequent filling during low recurrence interval floods. However, geological structures are only one control on the GSCS, and we present analyses of the host bedrock, including the qualitative results of thin-section studies designed to understand stratigraphic perching and selective cave development in certain lithologies. The information gained can be used to make predictions about flow routes and master conduits that have yet to be observed once additional data is collected.

Committee: Gregory Springer Dr (Advisor); Eung Seok Lee Dr. (Committee Member); Keith Milam Dr. (Committee Member) Subjects: Environmental Science; Geological; Geology; Geomorphology

Master of Science, The Ohio State University, 2022, Environment and Natural Resources

Unmanned aerial vehicles (UAVs) have an increasingly relevant role in the field of hydrology and water resources management. Their affordability and ease of use in comparison to traditional field-based methods have made research on their applications increase rapidly in the past decade. One application of UAVs to the hydrology of river systems is the estimation of particle sizes within a channel. This project investigated the ability of UAV imagery and Structure-from-Motion (SfM) photogrammetry to estimate grain-size distributions within a reach along the Olentangy River. To do this, we selected a study reach within the Highbanks Metro Park that was approximately 250 m in length and 50 m in width. We flew a DJI Mavic 2 Pro quadcopter UAV and collected imagery of subaerially exposed grains throughout gravels bars within this study reach. These images were processed using a SfM workflow that yielded point clouds and orthomosaics from which we extracted multiple topography-based and image-based metrics to be used as proxies for grain sizes. We then calibrated statistical regression models to predict the D50 and D84 grain size percentiles from these grain size proxies. While previous literature has suggested that topographic roughness metrics outperform image textural metrics for statistical grain size estimation, our study showed that the statistical models that were calibrated based on image textural properties performed better than those that were calibrated based on point cloud roughness properties. This contradiction may reflect the unique nature of our study site where the grains were dominated by smaller particles in comparison to other studies. The smaller grain sizes in our study area would have likely produced less significant topographic signatures in comparison to larger grains, which makes topographic roughness difficult to accurately measure and apply to statistical grain size estimation techniques. The results of this study suggest that topography-based g (open full item for complete abstract)

Committee: Steve Lyon (Advisor); Sami Khanal (Committee Member); Kaiguang Zhao (Committee Member) Subjects: Environmental Science; Geology; Geomorphology; Hydrologic Sciences; Hydrology; Water Resource Management

Master of Arts, The Ohio State University, 2022, Geography

Improving tropical glacier modeling capacity is crucial for deriving climatological insight from tropical glacier fluctuations on historical to multi-millennial timescales and for predicting socially relevant glacier environmental changes under anthropogenic climate warming. Using the glacierized Queshque Valley of Peru's Cordillera Blanca as a case study, this thesis first develops data assimilation and calibration methods to adapt a coupled temperature-index mass balance and glacier flow model to tropical settings. The calibrated model is applied to project glacier evolution in the valley under an ensemble of climate change scenarios, confirming the high probability of near complete deglaciation by the end of this century. Despite the glacier's current trajectory, moraine features signal that ice once extended about 6km further down valley. Three cosmogenic nuclide dated moraines reveal extended ice cover at 10.8ka, 9.4ka, and 6.2ka BP, and historical maps show that the glaciers have retreated considerably since 1962 CE. Equilibrium experiments are used to identify all possible climatic conditions producing stable glaciers at the positions marked by the moraines and historical ice limit. Relative to the 1985-2015 CE climatic baseline, results suggest that valley temperatures were 2.9-1.9˚C cooler at 10.8ka BP and at least 1.0˚C cooler at 9.4ka BP. Proximity between the 9.6ka and 6.2ka moraines makes their climatic signatures difficult to distinguish. Finally, the equilibrium experiment confirms that in 1962 the glacier was already far out of balance. In summary, this thesis presents a data-intensive approach to improving model performance on a tropical glacier, enabling accurate ice loss projections, and helping to constrain paleoclimatic interpretations of tropical glacier geomorphology.

Committee: Bryan Mark (Advisor); Zhengyu Liu (Committee Member); Ellen Mosley-Thompson (Committee Member) Subjects: Geography; Geomorphology

Master of Arts, University of Toledo, 2021, Geography

On February 15th, 2019, Indiana Dunes was elevated to the designation of a U.S. National Park. Along with this designation belongs the credo of the U.S. National Park Service, to conserve such places that are deem naturally, historically, or in so many words ecologically important by such means as will leave them unimpaired for the enjoyment of future generations. In 2019, the water level in Lake Michigan was trending above the long term recorded average, and as a result several locations in the National Park sustained damage due to erosion and inundation. Current water levels are receding, but predictions suggest that fluctuations from low to high periods will becomes more frequent and more severe. Acknowledging that this may be a certain outcome, requires a great understanding of the shoreline morphology within the National Park, especially considering such namesake features as the shoreline dunes. This study uses LiDAR data from an era of below average to a period of elevated water level for five areas of interest within Indiana Dunes National Park, to categorize levels of change in the near shore and beach regions, as well as quantify metrics of beach width change. Resulting in several Areas of Interest containing mixed values of dune elevation loss with some gain. Importantly identifying that Mount Baldy and Central Avenue Beach have majorly experienced dune elevation loss where iv gains were not seen based on dune migration. Additional findings include the massive inundation of beach area and substantial loss of foredunes at Portage Beach and the token area of Beach width gain at Beverly Shores (East).

Committee: Patrick Lawrence (Committee Chair); Kevin Czajkowski (Committee Member); Ricky Becker (Committee Member) Subjects: Geography; Geomorphology; Remote Sensing

PhD, University of Cincinnati, 2021, Arts and Sciences: Geology

How do karst landscapes evolve over thousands to millions of years? How do various erosional processes contribute to that evolution? These are persistent questions in geomorphology and speleology. This dissertation addresses the question of processes from an erosion, transport, and deposition perspective. First, I cover the numerical modeling of abrasional wear by sediment transport in a cave passage, proposing a set of erosional zones comparing the contributions from dissolution and abrasion to the enlargement of cave passages. I then discuss the initiation of a long-term micro-erosion monitoring study in a cave river in Mammoth Cave National Park. It is anticipated that decades from now, data from that project will provide additional evidence to validate or refute the numerical modeling results. Next, I share the fieldwork investigation results of a sediment deposit in a different portion of Mammoth Cave. This was determined to be a debris flow deposit and a timeline of events leading to its deposition was proposed. Finally, I present the curricula of two activities designed to present karst hydrology and geomorphology to a wide variety of learners. These were then incorporated into Virtual Capstone Pathways to provide accessible and inclusive online options for undergraduate students. Deeply understanding our landscapes and their processes, and communicating about that knowledge effectively and accessibly can help people be passionate stewards of the land and of knowledge.

Committee: Dylan Ward Ph.D. (Committee Chair); Shaaban Abdallah Ph.D. (Committee Member); Matthew Covington Ph.D. (Committee Member); Craig Dietsch Ph.D. (Committee Member); Mohamad Reza Soltanian Pereshkafti (Committee Member) Subjects: Geomorphology

Master of Science, The Ohio State University, 2021, Earth Sciences

The Chandeleur Slide is a large submarine landslide on the Gulf of Mexico seafloor in approximately 1100 meters of water, 200 km southeast of New Orleans, LA. This part of the Mississippi Fan received high sedimentation throughout the Pleistocene, causing high pore fluid pressure and abundant slope failures, though few as large as the Chandeleur. Given its proximity to major coastal cities, oil and gas infrastructure, and its large size, I examine the Chandeleur Slide to: (1) map the location and thickness of the displaced sediment, (2) understand what led to the initial slope failure, (3) decipher if this was a fast-moving or slow-moving event, and (4) consider potential hazard implications a slide like the Chandeleur represents for seafloor infrastructures and tsunami risks to coastal communities surrounding the Gulf of Mexico. I interpreted publicly available 2D and 3D multichannel seismic surveys and high-resolution bathymetry data to reveal several flow paths generally due south/southeast, and a slow-moving sediment mass with a translational-rotational behavior. The Chandeleur Slide includes extensional faulting in the headscarp area and compressional structures in the northern-most toe confined by a natural ramp-like structure. Beneath the Chandeleur Slide, I observe an upward-migrating salt body that has compressed a regional sand-rich unit (the Blue Unit). I interpret that the upward-migrating salt led to overpressure within Blue Unit sand layers, facilitating the initial failure of the Chandeleur. After failure, the Chandeleur Slide transported a large volume of sediment southward but was blocked by antecedent topographic highs that deflected much of the sediment to the south/southwest. The initial failure was followed by retrogressive headwall retreat northward, which created the prominent scarp on the seafloor. In total, the Chandeleur Slide comprises an area just over 1000 km2 and contains about 300 km3 of failed sediment.

Committee: Derek Sawyer Dr. (Advisor); Ann Cook Dr. (Committee Member); Daniel Pradel Dr. (Committee Member) Subjects: Earth; Environmental Geology; Geographic Information Science; Geological; Geology; Geomorphology; Geophysics; Geotechnology; Marine Geology

Master of Science (MS), Ohio University, 2021, Geological Sciences (Arts and Sciences)

Scallops are concave dissolution features that can form on soluble surfaces. These features have been used to recreate paleoflow conditions within cave systems. The goal of this study was to expand the knowledge of scallop spatial distributions and related statistics. We tested scallops' spatial distributions against random Poisson distributions. In order to test this, we measured scallops from Buckeye Creek Cave and the Boarhole Portal Cave System in Greenbrier, West Virginia and we performed statistical analyses on those measurements. We looked at the variance in scallop lengths between the two caves to determine if the distributions were statistically similar and concluded they were not. We then compared the variances of scallops on a vertical transect to those on a horizontal transect and found that this was inconclusive depending on passage geometry. Scallop distributions were compared to a random Poisson distribution and it was found that both cave's scallop distributions follow a random Poisson distribution, but are weakly inhibited. This was then corroborated by nearest neighbor analysis of scallops showing normality of the nearest neighbor distances, implying random relationships. Together, these results expand on reconstructing paleoflow with the of the spatial distribution of scallops. However, more work is needed to further understand the significance cave geometry contributes to reconstruction with scallop distribution.

Committee: Gregory Springer (Advisor); Katherine Fornash (Committee Member); Eung Seok Lee (Committee Member) Subjects: Geological; Geology; Geomorphology; Hydrology

Master of Science, University of Toledo, 2020, Geology

The rate of melting in glaciers around the world is accelerating due to global climate change, and this is projected to increase global sea level over the next century. Understanding subglacial hydrology will be key to being able to predict how glaciers will transport and store meltwater. Recent releases of high-resolution elevation data throughout the Midwestern United States have revealed numerous subglacial landforms that were previously unmapped, which may give insight into the subglacial hydrology of the Laurentide Ice Sheet (LIS). The focus of this study was to identify the stratigraphy and formation of new landforms known as Parallel Tunnel Channels (PTCs) that have been observed in northeastern Indiana, northwestern Ohio, and southeastern Michigan. PTCs consist of a chain of parallel, discontinuous depressions separated by a central ridge, crosscut recessional moraines, and many eventually lead to traditional tunnel channels. A PTC near the town of Auburn, Indiana studied using IDNR water well logs, a vibracore, and electrical resistivity surveys. The results suggest that the PTC is underlain by a partially laterally continuous, shallow, confined aquifer and its depressions were cut by meltwater. An additional PTC-like feature known as the Upland Channels near the town of Upland, Indiana was studied using passive seismic surveys. The surveys identified a buried valley following the length of the Upland Channels. An experimental physical model was constructed to investigate the surficial expression of an overpressurized, confined aquifer. The result of the experiment was numerous blowouts occurring along the margins of the confined aquifer, bringing groundwater to the surface. Based on the results, PTCs are hypothesized to form subglacially within an active R-channel, creating a connection between the base of the LIS and the confined aquifer. The Upland Channels are hypothesized to form proglacially along the margin of the LIS and are therefore not true PT (open full item for complete abstract)

Committee: Timothy Fisher (Committee Co-Chair); Richard Becker (Committee Co-Chair); Henry Loope (Committee Member); James Martin-Hayden (Committee Member) Subjects: Geology; Geomorphology

Bachelor of Science, Marietta College, 0, Petroleum Engineering and Geology

Located at the confluence of the Allegheny, Monongahela, and Ohio Rivers, Pittsburgh grew from a small colonial town to an American industrial giant over a span of a little more than one hundred years. Today, although no longer an industrial hub, Pittsburgh is still reliant on the remnants of the city's growth and its adaptation to geography. This project is an interdisciplinary study, combining geological and historical research, aimed to investigate the social implications of geology, geomorphology, and geography in Pittsburgh, Pennsylvania. The city was initially divided by the three rivers in three distinct towns, Pittsburgh, Allegheny City to the north, and Birmingham to the south. Although divided, their growing industries and economies were intertwined, encouraging human adaptation through significant infrastructural developments such as bridges, inclines, and tunnels. Furthermore, the rivers, although divisive, also became an essential piece that connected Pittsburgh to the rest of the country. Rivers were used for transportation of goods by boat since Pittsburgh's founding, and the invention of the steam engine and establishment of railroads loaded the river banks and floodplains with tracks and stations throughout the city. Pittsburgh's identity lies in its bridges, inclines, and tunnels: infrastructural proof of the people's adaption to the divisive geography.

Committee: Wendy Bartlett MS (Advisor); McDaniel Katy PhD (Committee Member); Johnson Grace MA (Committee Member) Subjects: Geography; Geology; History

PhD, University of Cincinnati, 2019, Arts and Sciences: Geology

The southern end of the Lesser Antilles subduction zone is considered to be a type-locality of Subduction-Transform Edge Propagator (STEP) faulting, where lithospheric tearing facilities the transition from subduction of the South American plate to transform motion of the Caribbean plate. Regions where plate boundaries transition from subduction to transform motion are sites of complex tectonic and deformation processes that are not well understood. The shallow emergence of the islands of Trinidad and Tobago that sit directly above the southeast Caribbean plate corner provide a unique setting to investigate the influence of the plate transition on shallow crustal deformation. In this dissertation, I characterize crustal deformation of the mountains of Trinidad and Tobago to evaluate the influence of the STEP fault transition at southeast Caribbean plate corner on the tectonic and geomorphic evolution of the mountains. Crustal deformation is examined through time-scales between 106 –103 years and from crustal depths of ~10 km to the surface in the mountains of Trinidad and Tobago. Quaternary surface uplift rates are determined using optically stimulated luminescence ages from marine terraces in Trinidad's Northern Range to evaluate spatial and temporal patterns of neotectonic activity along the southeast Caribbean plate boundary and yield uplift rates from to ~0.7–2 mm/a since 80 ka to the present. Geomorphic analyses and cosmogenic 10Be data from the Northern Range, Trinidad and Main Ridge, Tobago are used to constrain rates of hillslope erosion (ranging from ~6–167 mm/a), to identify controls on catchment erosion, and to investigate the steadiness or transience of the landscape with respect to tectonics and fluctuations of climate and sea-level during the Quaternary. The exhumation history of the Northern Range, Trinidad and eastern Paria Peninsula, Venezuela are constrained with analyses of apatite fission-track and apatite and zircon (U-Th)/He thermochronology an (open full item for complete abstract)

Committee: Lewis Owen Ph.D. (Committee Chair); John C. Weber Ph.D. (Committee Member); Brooke Crowley Ph.D. (Committee Member); Craig Dietsch Ph.D. (Committee Member); Eva Enkelmann Ph.D. (Committee Member) Subjects: Geology

Doctor of Philosophy, The Ohio State University, 2019, Environment and Natural Resources

Urbanization of watersheds leads to myriad changes to streams, including modified sediment and streamflow regimes that can result in altered fluvial geomorphic processes and channel structure. Hydrogeomorphic features have been linked to community composition of aquatic biota, as well as to stream ecosystem functioning. Biotic communities in urban stream ecosystems can be markedly different than their counterparts in more natural streams, often exhibiting reduced abundance, diversity, and shifts in assemblage composition, though the specific mechanisms through which urban land use and subsequent hydrogeomorphic modification effects these changes remain unresolved. Hydrogeomorphic modifications may impact both instream habitat as well as connectivity to the surrounding landscape, influencing both biotic assemblage composition as well as ecological connectivity between streams and their adjacent riparian zones. In 23 small urban stream reaches in the Columbus Metropolitan Area (CMA), Ohio, USA, I investigated potential linkages between urban-induced hydrogeomorphic characteristics and: (1) fish assemblage compositional changes over time (3-5 years); (2) fish assemblage trophic dynamics; (3) aquatic-to-terrestrial nutritional subsidies to a common riparian consumer (spiders of the family Tetragnathidae); and (4) downstream drift of larval macroinvertebrates in the water column. Hydrogeomorphic features related to instream habitat, the hydraulic environment (e.g., slope, shear stress, D50 [median bed sediment particle size]) and stream-floodplain connectivity (e.g., entrenchment ratio, sinuosity, incision ratio) emerged as common influences on fish assemblage composition and trophic dynamics, aquatic-terrestrial connectivity, and invertebrate drift. At a subset of 12 study reaches, several hydrogeomorphic variables showed significant changes over 3-5 years, with many decreasing (e.g., discharge [by 39%], slope [by 0.1%], and shear stress [by 29%, which decreased in co (open full item for complete abstract)

Committee: Mažeika Sullivan PhD (Advisor); Lauren Pintor PhD (Committee Member); Charles Goebel PhD (Committee Member) Subjects: Aquatic Sciences; Ecology; Environmental Science

Master of Science (MS), Ohio University, 2019, Geological Sciences (Arts and Sciences)

Slackwater deposits and hydraulic modeling were used to extend the historical record of floods and determine the critical threshold of sediment entrainment in the Greenbrier River of southeastern West Virginia (SE WV). The southward flowing bedrock river incises Paleozoic sandstones, limestones, and shales. The river has experienced three catastrophic floods since 1985: the 1985, 1996, and 2016 floods, which caused extensive damage in communities alongside the river with the most recent flood destroying roughly 1,200 homes in the Greenbrier River watershed. This study better constrains the frequency of floods that have the potential to cause similar damage, which is a matter of urgent need. Paleostage indicators (PSIs) found in Greenbrier River Cave were used as proxies for extending the historical record and reconstructing recurrence intervals of floods. Radiocarbon dating was used to determine ages of pre-historic slackwater deposits (floods) in the cave. Wolman counts were performed in the river channel to determine stream competence and sediment transport thresholds. Known discharges and recoverable paleostages were used to calibrate channel roughness in a 1-dimensional modeling program, HEC-RAS. Channel roughness (Manning's n) during large floods was determined to be 0.029. Discharges and clast entrainment velocities were calculated using a Shield's critical shear stress equation and clast size data, then compared against velocities determined in HEC-RAS. HEC-RAS was used to back-calculate discharges for the pre-historic flood deposits which allowed for the 100-year flood frequency to be re-evaluated. Recurrence intervals were assigned to discharges, calculated from clast size data and critical shear stress equation, using the existing flood frequency analysis. The reliability of using paleostage indicators and HEC-RAS to create flood chronologies is discussed.

Committee: Gregory Springer (Advisor); Gregory Nadon (Committee Member); Dorothy Sack (Committee Member) Subjects: Geology; Geomorphology; Paleoclimate Science

MS, University of Cincinnati, 2019, Arts and Sciences: Geology

This study focused on glaciation in the South American Arid Diagonal (AD) climatic feature which intersects in the Andes mountain range at approximately 24°S. This NE-SW-trending zone of hyper-aridity separates the Atlantic-sourced Easterly moisture belt from the Pacific-sourced Westerly precipitation in the central Andes. We present new geomorphological maps of the landforms, particularly of glacial moraines across two mountain ranges within the Western Cordillera of the central Andes. Additionally, new 36Cl chronologies using surface exposure dating were produced from two sites near the northern boundary of the modern AD. One site is located in the Cordillera del Tatio at ~21°S (Tatio field site), the other is the southernmost valley in a stratovolcano chain called the Cordon de Puntas Negras at ~24°S (SPN field site). Paleo-ELAs were reconstructed utilizing a two-dimensional numerical model to simulate glaciers over a 90m digital elevation model of the upstream catchment. We find that four glacial stages were present at both field sites sampled. Glacial stabilizations from the El Tatio field site, once assumed Lateglacial in age are on the order of 10-20 thousand years older than previously published. Tatio ages ranged from ~25 ka to as early as MIS 5. We also found that dated glacial stages from El Tatio and the Puntas Negras are not synchronous with lake highstands on the Altiplano, but projected ages of the younger glacial stages indicate both sites were glaciated during the Tauca phase. Regional comparison indicated the possibility of glacial occupation of the Tatio site into the Lateglacial during the Coipasa phase (12 ka) after rapid deglaciation of the SPN field site. Regional ELA comparisons supported the trend of moisture loss from the NE to SW portions of the climatic AD feature.

Committee: Dylan Ward Ph.D. (Committee Chair); Aaron Diefendorf Ph.D. (Committee Member); Thomas Lowell Ph.D. (Committee Member) Subjects: Geology

MS, University of Cincinnati, 2018, Arts and Sciences: Geology

Topographic features created by glaciers can reveal how they erode bedrock. The goal of this study was to determine the relative roles of the glacier and bedrock in the formation of topographic features within two formerly glaciated valleys at scales of 10⁻² to 10¹ m. The relationship between glacial sliding, rock type (crystalline vs. sedimentary), and fractures was examined through measurements of fracture spacing and orientation in the field and through Fourier spectral analysis of high-resolution DEMs. Topographic data were collected through Structure-from-Motion (SfM) photogrammetry at fifteen field sites in Alaska Basin and Darby Canyon in the Teton Range, WY, USA. The Fourier spectral analysis revealed that significant topographic roughness developed on the glacier bed at wavelengths between 0.01 to 1 m. This is similar to the spacing of open fractures in the bedrock, suggesting that glacial erosion processes exploit the fractures, creating small-scale roughness. Two-dimensional spectral analysis showed that within the quartz monzonite and dolomite, significant roughness elements were aligned in directions either parallel or perpendicular to ice flow, but unrelated to the fracture orientations. Within the gneiss, the significant roughness elements were not aligned with the direction of ice flow, but were oriented perpendicular to the foliation and fractures. These results suggest that fracture spacing controls the spatial frequency of roughness, while the direction of ice flow controls its orientation. However, in certain rock types, heterogeneity within the rock can have more influence on the orientation of roughness than the direction of ice flow.

Committee: Dylan Ward Ph.D. (Committee Chair); Craig Dietsch Ph.D. (Committee Member); Thomas Lowell Ph.D. (Committee Member) Subjects: Geology