Intrusive rocks crop out in the East Range and Humboldt Range in Pershing County associated with the Koipato Group volcanic rocks (TRkv). They intrude upper Paleozoic rocks of the Golconda terrane (GC) and rocks of the Koipato Group. Limited older evidence suggests that these rocks may be Triassic (Silberling and Wallace, 1967; Wallace, Silberling, and others, 1969; Wallace, Tatlock, and Silberling, 1960; Wallace, Tatlock, and others, 1969), but new data (du Bray and Crafford, 2007) suggests that most of the intrusive rocks mapped as Triassic in the East and Humboldt Ranges are Cretaceous or younger. In northern Esmeralda County between the Royston Hills and the Monte Cristo Range small exposures of Upper Triassic plutons are inferred to relate to the Lee Vining intrusive epoch in eastern California (Stewart, 1980). These rocks also intrude into the Golconda terrane (GC).