This grant provides 50% of the costs of acquiring a Maran Ultra NMR core analyzer for the Environmental Geophysics Laboratory currently being built at Stanford University. The instrumentation will be used by the PI and graduate students investigating the use of NMR for environmental applications. In addition, it is likely that others will use the analyzer for research applications in the petroleum industry. There is growing interest in the use of NMR for characterizing the near-surface of the earth. The Maran analyzer is the central piece of equipment that will be used for laboratory studies of the relationship between measured NMR parameters and the basic physical and chemical properties of porous geological materials. The analyzer will be used to investigate the link between the NMR time constants and both the pore size distribution and tortuosity of materials. A second focus will be on improving the fundamental understanding of the mechanisms that control the NMR response in geological materials, with an emphasis on determining the role of paramagnetic species and the sensitivity to sorbed contaminants. This analyzer will be the first low field instrument of its kind at Stanford University, providing the capability to obtain laboratory data at the same frequency as that used in the collection of field and borehole data. The Maran analyzer will be housed in the Environmental Geophysics Laboratory, planned for construction in the summer of 2001. ***