The Cascades mountain range of southern Washington is a geologically complex and tectonically active region. The area has been explored for potential oil and gas reserves by several major oil companies, but exploration efforts (mostly electrical and seismic reflection surveys) are hampered by the geologic complexity which often leads to poor data quality. Although no commercial quantities of oil or gas have been found to date, the existence of major sedimentary basins and potential source rocks has lead to continued interest. The Department of Energy and the US Geological Survey have conducted geophysical studies in the southern Washington region to study possible petroleum-bearing sedimentary basins as well as crustal tectonic structures. The natural gas potential of deep sedimentary basins is an area of research supported by the Morgantown Energy Technology Center of DOE's Office of Fossil Energy. This report summarizes the work to date which has been conducted at LBL's Center for Computational Seismology. A major goal of our work is to investigate the seismic reflection characteristics of a possible marine sedimentary basin located between Mt. Rainier and Mt. St. Helens. The zone of interest was initially identified by magnetotelluric studies (Stanley et. al., 1987) as an anomalous conductor called the southern Washington Cascades conductor (SWCC). As part of our research we have studied several aspects of seismic imaging of the SWCC. Our work has included ray tracing and synthetic seismograms generated for planning and interpretation of explosive shots using a 1024 channel sign-bit acquisition system; a comparison of the signal strength and imaging capabilities of explosive and vibrioses sources, and processing and interpretation of one of a series of seismic reflection surveys conducted over the SWCC with the sign-bit recording system.