Named for Santa Fe railway station near Abo Pass in southeasternmost Valencia Co, NM. No type locality designated. Occurs as a belt, ranging from less than 500 ft to about 1000 ft wide, extending from north of Abo Pass southward along east flank of Los Pinos Mountains for about 5 miles in northeastern Socorro Co, NM in Orogrande basin. Varies from light to dark gray with greenish and nearly white facies in a few outcrops. Grain size rarely larger than 1 mm in diameter. Massive quartzose beds 3 to 5 ft thick alternate with thinner-bedded zones, commonly sericitic. Greatest thickness, about 600 ft, occurs at Abo Pass. Is oldest pre-Cambrian unit in study area. Conformably underlies pre-Cambrian Blue Springs schist (new). Geologic map. Measured stratigraphic cross sections. Structure cross sections. Pre-Cambrian age [presumably based on regional geology and stratigraphic position].

Source: GNU records (USGS DDS-6; Denver GNULEX).