Postcards from the Field
Sills near and sills far! — Cornudas Mountains, Otero County, NM
January 24, 2022
A sill is a tabular igneous intrusion that is parallel to the planar structure of the surrounding rocks, one of the many possible shapes that magmatic intrusions can form! Bureau geologists are working in the Cornudas Mountains (near the Texas state line in southernmost Otero County, NM) to map out and study the 25 to 40-million-year old magma bodies that tower proudly over the Otero Mesa. This work is part of an Earth MRI-funded collaboration between the New Mexico Bureau of Geology (led by Dr. Virginia McLemore), Texas Bureau of Economic Geology, and USGS to investigate the economic potential for critical mineral resources in the area. New Mexico Bureau scientists Snir Attia and Nels Iverson, along with graduate student Mason Woodard spent a recent weekend mapping several of the intrusive plugs, sills, and dikes found in the area.