Figure 4. Geologic map of the Ojo Alamo Sandstone type area. White arrowheads point to areas where paleomagnetic data were obtained from the Ojo Alamo Sandstone; HW = Hunter Wash, SM = South Mesa, BBA = Barnum Brown Amphitheater, and BSA = Barrel Spring Arroyo; WW marks the Williamson-Weil mammal quarry. Dinosaur-bone locality I, in the NW 1/4 Sec. 7, T. 24 N., R. 11 W., is locality where 34 bones from a single Hadrosaur were discovered and collected from Ojo Alamo Sandstone. Geology modified from Brown (1982) and Scott et al. (1979); base of Ojo Alamo Sandstone was remapped for this study. Numbers with D prefixes are USGS paleobotany locality numbers. Published palynomorph lists from this area and other areas are in tables in Appendix. BAA-1 through BAA-3 are palynologic sample localities of Baltz et al. (1966). Radiometric ages for sanidine crystals from altered volcanic ash beds H and J from Fassett and Steiner (1997) and Fassett (2000).