Third-day road log, from Alamogordo to White Sands, San Agustin Pass, Organ quarry, and Tortugas Mountain
— Virgil W. Lueth, Spencer G. Lucas, Katherine A. Giles, Barry S. Kues, and James Witcher

Today's trip begins with a quick traverse of the southern part of the Tularosa basin with a stop at the world famous White Sands National Monument. We will then continue our traverse as we proceed up an out of the basin and onto San Agustin Pass, which separates the Organ and San Andres Mountains. We continue across the pass to enter the structural boundary zone between the Jomada del Muerto (to the north) and the Mesilla (to the south) basins of the Rio Grande rift. Here, we stop to examine the northern end of the Organ batholith, in the southernmost San Andres Mountains and the interactions between igneous intrusions and their host rocks that resulted in a variety of ore deposit types. The trip then proceeds south, along the spectacular western flank of the Organ Mountains. The route then traverses to the southwest into the Mesilla basin for the final stop at Tortugas ("A") Mountain. Here, we discuss paleo hot springs deposits and moderm hydrology on the margins of a rift basin.