Pg. 165 (fig. 1), 167-170. Ingalls formation. Pyroxene and hornblende andesite mudflow breccia; local thin volcanic conglomerate at base; black-weathering craggy outcrops. Thickness along Red Clover Creek about 550 feet; in west-central part of quadrangle, maximum thickness appears to be about 800 feet, but section may be partly duplicated by faulting. Separated from underlying Eocene Lovejoy formation and overlying middle Miocene(?) Delleker formation by unconformities, both intervals marked by extensive faulting and erosion. In Red Clover Creek area, the Ingalls is on Lovejoy at all points where base is exposed; in east-central part of quadrangle, rests in many places on granitic and metamorphic rocks; in west-central part, lies on basement of metamorphic rocks but also overlaps edge of channels of unit here referred to as auriferous gravel, and in several instances it rests on metamorphic rocks on one side of a fault and on auriferous gravels on the other. No area can be designated as type because of variability of composition and thickness from one part of quadrangle to another. Age is Oligocene(?).
Named from Mount Ingalls in northern part of Blairsden quadrangle. Well exposed along Red Clover Creek, northeastern CA.

Source: US geologic names lexicon (USGS Bull. 1200, p. 1868).