Earth and Space Sciences
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Large woody debris and river morphology in scour pool formation, dam removal, and delta formation
The interactions between large woody debris, fluid flow, and sediment transport are a first-order control on river processes, affecting channel morphology at multiple scales. This thesis investigates how wood geometry and ... -
Modeling firn densification through viscosity and microstructures
Knowledge of firn densification is important for several applications, such as for ice-sheet surface elevation changes from repeat satellite altimetry methods used to estimate ice-sheet contribution to sea-level rise. ... -
Landslides in Cascadia: Using geochronometry and spatial analysis to understand the timing, triggering and spatial distribution of slope failures in the Pacific Northwest United States
Landslides kill hundreds to thousands of people every year, cause billions of dollars in infrastructure damage, and act as important drivers of landscape evolution. In the Pacific Northwest USA, landslides routinely block ... -
Landscape Response to Oblique Convergence: Insights from Numerical Modeling and from the Marlborough Fault System, New Zealand
Strike-slip and oblique faults are prominent tectonic features that can dramatically influence the landscape at all scales. In this dissertation, I explore the effects of strike-slip and oblique faults on the landscape, ... -
The history, hydraulics, and geomorphic impact of outburst floods in the eastern Himalaya
Outburst floods have shaped many landscapes on Earth and represent a significant geologic hazard, but they are relatively infrequent, and we must rely on the sedimentary record to study the most extreme events that have ... -
From Earth to exoplanets: Quantifying atmospheric biosignatures and biogeochemical controls on habitability
It will soon be possible to determine the atmospheric composition of potentially habitable planets around other stars via astronomical observations. This raises the exciting possibility of detecting life remotely from its ... -
Co-evolution of Life and Environment across Earth History: Empirical & Modeling Constraints on Nutrient Cycling, the Rise of Oxygen, and Eukaryotic Evolution
That life and its environment have co-evolved through Earth’s history, and in doing so have maintained the conditions required for planetary habitability, is one of the great discoveries in the natural sciences during 20th ... -
Terrestrial Paleoclimate of the Cenozoic: Insights from and Developments of the Soil Carbonate Clumped Isotope Thermometer
Land temperature at the surface of the Earth is a first-order parameter used to describe climate, but reliable and widespread measurements of this basic parameter through geologic time has eluded geochemists and geologists ... -
Quaternary grounding-line fluctuations in Antarctica
The West Antarctic Ice Sheet may be prone to rapid collapse under climates warmer than today due to a dynamic instability at the grounding line, where the ice sheet goes afloat over seawater. However, there is to-date no ... -
Geomorphic and Atmospheric Investigations on the Habitability of Past and Present Mars
While the current surface of Mars is viewed to be inhospitable to life as we know it, past Mars may have harbored habitable environments though the extent and duration of such environment is still unclear. There are several ... -
Understanding Antarctic ice-stream flow using ice-flow models and geophysical observations
Ice streams are the primary pathway by which Antarctic ice is evacuated to the ocean. Because the Antarctic ice sheets lose mass primarily through oceanic melt and calving, ice-stream dynamics exert a primary control on ... -
Magnesium isotope fractionation associated with biotic and abiotic weathering -and- Developing a scalable method for rare earth element extraction from non-traditional feedstocks using engineered Escherichia coli
This dissertation is divided into two sections, with the first discussing magnesium (Mg) isotope behavior during biotic and abiotic rock weathering, and the second describing the application of engineered microbes for the ... -
An investigation of lightning-generated whistler waves in the inner magnetosphere
In this dissertation, we use a new and unique dataset to investigate lightning-generated whistler waves in the Earth’s inner magnetosphere. Global lightning data and high-resolution waveform data in the inner magnetosphere ... -
Testing the theory of radiation belt electron loss by hiss and electromagnetic ion cyclotron waves
Hiss, chorus and electromagnetic ion cyclotron waves (EMIC wave) are three major wave modes that are widely investigated and included in the radiation belt electron models to explain electron precipitation. The quasi-linear ... -
Understanding ice-sheet dynamics using geophysical observations and numerical ice-flow models
Mass loss from the world’s ice sheets is one of the largest sources of uncertainty in sea-level rise projections for the 21st century. One way to improve sea-level rise projections is to better understand the processes ... -
Structural controls and diagenetic conditions associated with fluid migration on the Moab Fault, UT
Faults and fault zones can have strong effects on fluid migration within the Earth’s crust, with important implications for resource management and earthquake hazards. The research presented within this dissertation addresses ... -
A window into terrestrial paleoclimate: soil carbonate formation processes and climate proxy applications
The isotopic composition of pedogenic (formed in soil) carbonates provides a geologically abundant archive of terrestrial climate change and the interactions between Earth’s climate, geologic, and biologic systems. However, ... -
Imaging northern Cascadia wave speed structure and slow slip
I calculate tremor source amplitudes for the northern Cascadia episodic tremor and slip (ETS) events from 2007-2010 and find they exhibit similar spatiotemporal patterns of radiated energy from tectonic tremor. In the ... -
The co-evolution of life and the nitrogen cycle on the early Earth
Nitrogen is an essential element for all life as we know it. Its abundance and speciation in the atmosphere and ocean has been dynamic through Earth’s history. The dynamic nature of nitrogen cycling is invariably linked ... -
Quaternary glaciation in Central Asia
The mountain ranges in Central Asia were heavily glaciated during the Quaternary Period. The relative magnitudes of paleoglaciers varied spatially and temporally. The chronology of glacial standstills was established from ...
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