Third-Day Road Log: From Circle A Ranch to The Fisher Trail, Nacimiento Mine Site, and The San Gregorio Trailhead
— Kevin M. Hobbs

Day 3 of the field conference focuses on areas on the Sierra Nacimiento mountain front near Cuba. Neotectonic uplift and erosion recorded in well-developed fluvial terraces are the focus of Stop 1, which affords an early-morning view of the mountain front and hands-on looks at the evidence for past stream power. We cross to the east side of U.S. Route 550 for Stop 2, visiting the site of the former Nacimiento Mine—once the economic lifeblood of Cuba, now a case study in postmining environmental issues—to discuss Triassic sedimentation, copper mineralization, and groundwater remediation at a newly- accessible set of trails and facilities. For Stop 3, we head high into the Sierra Nacimiento to see Paleoproterozoic granites that represent the basement upon which New Mexico’s Phanerozoic geologic history has been constructed. There, we discuss the interplay between hydrology and development, what the oldest rocks on the field trip can tell us, and then (hopefully) tie the conference together with a consideration of feedbacks between rock production, weathering, sedimentation, uplift, and subsidence.