The Honey Lake fault zone is one of four major, northwest-striking dextral faults that constitute the northern Walker Lane in northwestern Nevada and northeastern California. Global positioning system (GPS) geodetic data indicate that the northern Walker Lane accommodates ~10%–20% of the dextral motion between the North American and Pacific plates. Regional relations suggest that dextral movement in the Honey Lake area began ca. 6–3 Ma. Five 31.3–25.3 Ma ash-flow tuffs, totaling ~250 m in thickness, were distinguished in a paleovalley in the Black Mountain area of the Diamond Mountains, southwest of the Honey Lake fault. Four of these tuffs, totaling ~200 m in thickness, also occupy a paleovalley in the Fort Sage Mountains northeast of the fault. On the basis of the similar tuff sequences, we infer that the Diamond and Fort Sage Mountains contain offset segments of a once-continuous, westerly trending late Oligocene paleovalley. Paleomagnetic data from the 25.3 Ma Nine Hill Tuff indicate negligible vertical-axis rotation in the Diamond and Fort Sage Mountains. Correlation of the paleovalley segments in the Diamond and Fort Sage Mountains suggests 10–17 km of dextral displacement across the Honey Lake fault. About 10 km of offset is favored on the basis of constraints near the southeast end of the fault. The spread of possible offset values implies long-term slip rates of ~1.7–2.8 mm/yr for a 6 Ma initiation, and ~3.3–5.7 mm/yr for a 3 Ma initiation. These rates are comparable to slip rates inferred from Quaternary fault studies and GPS geodesy.

The Hunter Creek Sandstone of the Verdi Basin, Nevada, yielded a succession of superposed continental faunal assemblages ranging in age from the late Clarendonian (late Miocene) through the late Blancan (late Pliocene) in the North American land mammal age framework, or ca. 10.5–2.5 Ma. We describe two new local faunas from the Hunter Creek Sandstone: the East Verdi local fauna, of late-medial to late Clarendonian age, which includes Dinohippus cf. D. leardi , Camelidae, ?Antilocapridae, and Mammutidae or Gomphotheriidae; and the Mogul local fauna, of Hemphillian age, which includes Dinohippus sp., Rhinocerotidae, Camelidae (at least two species), Mammut sp., and possibly Gomphotheriidae. A third unnamed assemblage, of latest Hemphillian or earliest Blancan age, is represented by a small sample of fossils from W.M. Keck Museum locality P-105. The only taxa recovered from this locality are cf. Megatylopus and Gomphotheriidae or Mammutidae. A single late Blancan locality, the Byland locality, yielded Equus idahoensis . The recognition of this faunal succession provides a biostratigraphic framework for the Hunter Creek Sandstone that corroborates and is consistent with the previous chronostratigraphy based on radioisotopic and tephrochronologic dating methods.