Abstract The Franklin Mountains are located in far West Texas (ElPaso County) and southernmost central New Mexico (Dons Ana County). The range, when including the North Franklin Mountains (north of Anthony Gap), is 23 mi (38 km) long and less than 5 mi (8 km) wide (Fig. 1). It consists of a linear series of north–south-trending, westward-tilted fault blocks, which are bounded on the east and west by major normal faults. Gravity slides are common throughout the range. The mountains are reasonable examples of the basin-and-range structural and physiographic type. The structure is distinctly different from the thrusted (autochthon and three allochthons) Cretaceus sequence of the northern Chihuahuatrough of the Sierra de Juarez to the south in Mexico. The Texas lineament, the major structural feature separating these disparate northern and southern structural styles, if it exists, would pass through downtown El Paso. Access to the area is by 1-10. Three localities are suggested for examination (Fig. 1). Localities 1 and 2 are on paved, public thoroughfares. Locality 3 (Vinton Canyon) maybe reached from 1-10 at Westway, approximately 3 mi (4.8 km) south of the Texas-New Mexico line, byproceeding eastward on a dirt track toward the mountains. A high-clearance vehicle is required.

Abstract White Sands National Monument is located in west-central Otero and east-central Dona Ana Counties in south-central New Mexico (Fig. 1). It is within and bounded by the White Sands Missile Range. The monument has a visitor’s center with the usual facilities. It is open year-round with the single exception of Christmas Day. Summer hours (Memorial Day to Labor Day) are from 8 A.M. to 10 P.M. Winter hours are from 8:30 A.M. to sunset. Periodic trips to Lake Lucero led by monument personnel are planned for every other month. These trips are subject to change depending on weather conditions and the firing schedule at White Sands Missile Range. Information concerning these special trips may be obtained by phoning (505) 437-1058.

Abstract Lime mud that is abundant in all facies formed a hydrologic barrier that prevented migration of uranium solutions. Where original porosity did exist, is was occluded by calcite cement.