Fracture-controlled ground-water distribution adjacent to Los Esteros Reservoir, Guadalupe County, New Meixco
— Jay Lazarus

The Triassic Santa Rosa Sandstone occurs at shallow depths over much of northeastern New Mexico. Approximately 11 km north of Santa Rosa, New Mexico, bitumen-impregnated Santa Rosa Sandstone is visible at the surface. These outcrops of bitumen-impregnated sandstone are known as the Santa Rosa tar sands. They were mined in the 1930's for an asphalt-like road material, but are not currently produced. In 1982 and 1983, an evaluation of the bitumen reserves was undertaken for SOLV-EX Corporation, on its Riley Ranch lease adjacent to Los Esteros Reservoir, an irrigation and flood-control reservoir (Fig. 1). As part of the resource-evaluation program, 18 exploratory core-holes were cased and used for geohydrologic evaluation of the lease. Data collected indicate that structure features modified by solution/collapse processes in the Santa Rosa region strongly influence ground-water distribution and occurrence.