Mountains surround you. To your left is Dagger Mountain; to your right, the Rosillos Mountains stand 5,445 feet above sea level. On the distant horizon loom the Chisos Mountains lying in the heart of Big Bend National Park. The Rosillos Mountains formed as underground magma (molten rock) pushed upward but never reached the surface. The molten material bulged into a mushroom shape, coming to rest on top of older rock layers and doming the others above it. The roan-colored (rosillos in Spanish) mountains you see are composed of this igneous rock which cooled and lay far below the surface. Over time, erosion has chiseled away the overlying rock, exposing the once molten mass.