These correlations are important for both paleomagnetic studies within the region and for establishing geologic ties across the Gulf of California. Rotational deformation north of the PVP may have begun contemporaneously with this adjustment along the Gulf Extensional Province rift margin. Ar Data Figures Figure 1 . Figure 2 . Informal names given here include Santa Isabel Wash, Arroyo Oculto, and Cuervo Negro and Santa Isabel faults.
Subscripts are abbreviations of informal unit names.
One anomalously young sample age for Tmr siw , interpreted to be the result of glass contamination, is not listed. The stratigraphic relationship between group 7 lava flows is not apparent in the field except that Tmr can clearly overlies Tma gem . Error bars on individual data points are 1 s . Figure 4 . Stratigraphy from other studies has been simplified by listing only the lithologic units relevant to the discussion.