1. Background information to accompany folio of geologic, mineral resource, geochemical, aeromagnetic, and gravity maps of the Hillsboro and San Lorenzo quadrangles, Sierra and Grant Counties, New Mexico Author/Creator: Hedlund, David Carl, 1924- author Publication/Creation: [Reston, Virginia] : United States Department of the Interior, Geological Survey, 1979 Format: Book Access & Availability: Loading