Stratigraphic correlation chart for western Colorado and northwestern New Mexico
— Marjorie E. MacLachlan

The stratigraphic nomenclature applied in various parts of west-ern Colorado, northwestern New Mexico, and a small part of east- central Utah is summarized in the accompanying chart (fig. 1). The locations of the areas, indicated by letters, are shown on the index map (fig. 2). Sources of information used in compiling the chart are shown by numbers in brackets beneath the headings for the columns. The numbers are keyed to references in an accompanying list. Ages where known are shown by numbers in parentheses in millions of years after the rock name or in parentheses on the line separating two chronostratigraphic units.

No Quaternary rocks nor small igneous bodies, such as dikes, have been included on this chart. Because space is limited, all the accepted formal stratigraphic-rank endings for each of the units are abbreviated (Cgl, Conglomerate; Dol, Dolomite; Fm, Forma-tion; Gb, Gabbro; Gp, Group; Gn, Gneiss, Gr, Granite; Ls, Lime-stone; M, Member; Monz, Monzonite; Qtz, Quartz; Qtzite, Quartzite; Ss, Sandstone; Sh, Shale; T, Tongue). Other abbreviations used are Can for Canyon, Cr for Creek, and pt for part. Dashed lines where used as boundaries for stratigraphic units on the chart indicate that the upper and (or) lower time span is uncertain.