El Malpais - La Ventana Natural Arch
La Ventana Natural Arch is located along Highway 117 on the east side of the National Monument. It is one of the largest natural arches in New Mexico. The eastern escarpment of the Cebollita Mesa consists of cliffs of Jurassic Zuni Sandstone capped by Cretaceous Dakota Sandstone. The arch formed in the Zuni Sandstone. The arch is just outside of the National Monument on the El Malpais National Conservation Area (BLM, 2010).