Third-day road log, from Deming to Victorio Canyon and the southern Florida Mountains
— Nancy J. McMillan, Virginia T. McLemore, Jeffrey M. Amato, John W. Hawley, and Katherine A. Giles

The third-day tour will circumnavigate the Florida Mountains, a Basin-and-Range horst surrounded by well-developed alluvial fans. The route approaches the Florida Mountains from the north, passing the mid-Tertiary silicic volcanic complex of the Little Florida Mountains and towering spires of volcaniclastic beds of the Eocene Rubio Peak Formation. The nonconformity between basement and Phanerozoic sedimentary rocks takes on several expressions in the Florida Mountains. As the route proceeds south on the east side of the range, the nonconformity first appears between the Eocene Lobo Formation and the Cambrian Florida Mountains intrusion; farther to the south (and at Stop 1), the nonconformity is formed by Ordovician Bliss Sandstone on top of the intrusion.

Nestled in the eroded top of the Florida Mountains intrusion, Victorio Canyon provides the opportunity to discuss evidence for a major magmatic-tectonic event in New Mexico and Colorado during Cambrian-Ordovician time and its possible impact on the geologic history of the region at Stop I. The traverse crosses the upper eroded surface of the pluton into the overlying Bliss Sandstone and El Paso Limestone of the lower Paleozoic sedimentary succession. The traverse then climbs the canyon wall to reach controversial low-angle faults that have placed deformed El Paso Limestone, Ordovician Montoya Dolomite, and Silurian Fusselman Dolomite on top of the tilted Florida Mountains pluton and its sedimentary cover.

The trip will retrace its path around the north end of the Florida Mountains and drive south on NM-11 on the west side of the range to reach Stop 2. Exposed in the deeper section of the Florida Mountains pluton are examples of magma mixing that formed when mafic magma intruded the partially crystallized, but still mushy, Florida Mountains orthoclase granite.