In this dissertation, I develop some theoretical tools to interpret measurements of magnetization in rocks, sediments and soils. I show that the magnetization curve for an ensemble of superparamagnetic particles depends only on odd moments of the volume distribution $\rm(\langle V\rangle,\langle V\sp3\rangle,\...).$ As long ...

The tectonic evolution of the Juan de Fuca plate system has undergone dramatic changes over the past several million years as evidenced by seafloor geomagnetic data. If there are large geodynamic forces active in the subduction of oceanic lithosphere, corresponding changes in the structure of the Cascadia subduction zone ...

Using teleseismic network data and new signal processing techniques, I investigated mantle structure in the vicinity of subduction zones. The 660-km seismic discontinuity in the Izu-Bonin region is depressed by up to 80 km, indicative of material 1000$\sp\circ$K colder than ambient mantle. A broad depression of the discontinuity ...

The Columbia River has a large, biologically productive estuary whose ecosystem depends on the balance of salt and fresh water. Outflow from the river also forms a vast buoyant plume which affects circulation for hundreds of miles along the coast. Both the estuarine salt balance and the initial state of the plume are determined ...