The Colorado Rockies end in the Sangre de Cristo Range between Santa Fe and Las Vegas, New Mexico. At this latitude the Colorado Rockies are bipronged, consisting of the Santa Fe Range on the west and the Las Vegas Range on the east, with a synclinorium lying between the two. South of the end of the Santa Fe front a mild line of deformation continues for 60 mi along a monocline between Glorieta Mesa and the Estancia Valley downwarp. This trend dies out near the southern end of the Pedernal uplift near U.S. Highway 60.

The eastern front of the Colorado Rockies dies out at the end of the Las Vegas Range a few miles south of Las Vegas. Recent mapping in eastern New Mexico reveals a lineament of structures aligned southward from the Las Vegas front for nearly 200 mi. The principal elements of this alignment are the Anton Chico monocline, Leon anticline, Vaughn sag, Nalda shear zone, Tinnie fold belt, and Dunken uplift. Lesser folds and faults connect the above features along the lineament. These structures may reflect movement on a basement fracture zone which also determined the alignment of the eastern front of the Rockies.

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