Data from the North Pahroc and Seaman Ranges, Nevada, constrain the timing of extension and volcanism as well as faulting characteristics. These ranges record four separate episodes of normal faulting over a period of more than 31 m.y.: (1) prevolcanic normal faults older than 31 Ma; (2) small separation, synvolcanic faults that were active between 30 and 27 Ma; (3) faults that are bracketed between 18.8 Ma and the Quaternary but that, based on stratigraphic evidence, probably were active around 15 Ma; and (4) Pliocene-Quaternary faults that control modern basin-range topography. The hypothesized breakaway for the prevolcanic extensional system, the Seaman breakaway, appears to underlie the southern White River Valley. The Miocene faults in the North Pahroc Range may be upper-plate faults to the west-dipping Highland detachment, exposed east of the North Pahroc Range. These two major extensional systems were active in this area at different times, defining two overlapping regions of different ages of major crustal extension.