Publication Date


Date of Final Oral Examination (Defense)


Type of Culminating Activity


Degree Title

Master of Science in Geophysics



Major Advisor

John Bradford, Ph.D.


James P. McNamara, Ph.D.


Lee M. Liberty, M.S.


The critical zone is defined as the upper most portion of the crust extending from the top of unweathered bedrock to the top of the vegetation canopy. It is the zone in which inorganic rock is transformed into biologically useful soils and saprolites in a process termed weathering. Because the critical zone is the connection between the subsurface and surface it plays a role in a wide variety of biological, hydrologic, and climatic processes. Understanding the critical zone though is inherently difficult because its scale and heterogeneity often means direct sampling methods, e.g. soil pits and cores, under represent the heterogeneous critical zone process. Geophysical methods are increasingly applied to study the near-surface processes at a variety of spatial and temporal scales. This paper presents two geophysical experiments that capture two different hydrologic processes and two different scales: the first is the study of the influence of aspect, elevation, and snow accumulation on weathering depths at the catchment scales using seismic refraction tomography and second is the application of electrical resistivity tomography to observe the heterogeneous seasonal change of soil moisture and its connectivity at the plot scale.