Figure 4 . Stratigraphy from other studies has been simplified by listing only the lithologic units relevant to the discussion. Figure 5 . Stratigraphic columns showing preferred correlations between Group 6 and 7 rocks defined in Santa Isabel Wash and those described by other workers in nearby localities. In some cases the stratigraphy from other studies has been simplified by listing only the lithologic units relevant to the discussion.
Stratigraphic order is preserved in all cases.
Stratigraphic order of some Group 7 units is ambiguous.