Figure 27. Cross section through six paleomagnetic sections of Paleocene and uppermost Cretaceous (Campanian) strata in southwest San Juan Basin using base of magnetochron C29n as a datum. Boundaries for chrons C28r, C29n.1r, and C29n.2n are adjusted to make the thicknesses of these chrons as close to the same as possible at each locality, while still honoring the magnetic-polarity-site data. The resulting average thickness of C29n.1r is about 7 m.; for C29n.2n average thickness is about 11 m. Thickness of chron C28r and position of base of Ojo Alamo Sandstone on column BSA are corrected from thickness and position shown in Lindsay et al. (1981, figure 7) based on field studies in this area. Figures containing paleomagnetic data plots and photographs at these localities (except for KW section) listed on Figure 26.