Pg. 35 (table), 45-52. Hartford Hill rhyolite. Described as biotite rhyolite with some quartz latite; occasional underlying lenses of dacite; in places rhyolite overlies fanglomerate or auriferous gravels. Exposures commonly buff to reddish-brown, although some dense glassy facies are lavender; usually light colored, commonly almost white on fresh surfaces. Attains thickness of 450 feet on Hartford Hill. Overlies conglomeratic material at south end of Hartford Hill. Underlies with erosional unconformity Alta andesite (new). Age is considered Eocene based on stratigraphic relations.
Mapped in Silver City district and south end of Virginia Range, 12 mi northeast of Carson City, western NV.
See also V.P. Gianella, 1934, Mining and Metallurgy, v. 15, no. 331, p. 299 (table 1). Name Hartford Hill rhyolite appears only on table. Age is Miocene(?). Thickness 400 feet.

Source: US geologic names lexicon (USGS Bull. 1200, p. 1690); supplemental information from GNU records (USGS DDS-6; Menlo GNULEX).

Pg. 50, pl. 3. Hartford Hill rhyolite tuff. Redescribed as light-pink to dull-purple vitric-crystal tuff, tuff-breccia, and welded tuff. Includes a few feet of conglomerate at its base on south slopes of Hartford Hill. Fragments of granitic and metamorphic rocks are common and, in a few places, constitute as much as 10 percent of the rock. Thickness at type locality about 1,000 feet. Some interbedding with overlying Alta formation. Type locality and geographic extent indicated. Age is partly Oligocene(?) but may be partly or mainly Eocene(?).
Type locality: Hartford Hill, near Silver City, [Virginia Range, near Storey-Lyon Co. line], Virginia City 15-min quadrangle, western NV. Extensively exposed in Comstock Lode district and south and southwest of Virginia City quadrangle.

Source: Publication; US geologic names lexicon (USGS Bull. 1200, p. 1690).

K-Ar ages on sanidine and plagioclase from Hartford Hill Rhyolite yielded 22.8 and 22.7 Ma.
Sample locality: 5 mi southwest of Wadsworth, NV, in SW/4 NE/4 sec. 14, T. 20 N., R. 23 E., just north of Highway 40.

Source: GNU records (USGS DDS-6; Menlo GNULEX).

Mapped in Lyon, Douglas and Ormsby Counties, Nevada. Rocks of Hartford Hill Rhyolite Tuff lie at base of Tertiary section of andesitic rocks and overlie granitic or metamorphic rock except in Virginia Range where unit overlies 300 ft of claystone and near Yerington where unit overlies conglomerate. Age is considered early Miocene based on isotopic dating (Evernden and James, 1964)

Source: GNU records (USGS DDS-6; Menlo GNULEX).

Mapping in Carson City-Silver City area reveals that rocks included in Hartford Hill Rhyolite Tuff make up diverse sequence of welded and ash-flow tuffs ranging in age from 28 to 22 Ma. Name Hartford Hill abandoned and replaced by (oldest to youngest): Mickey Pass Tuff, Lenihan Canyon Tuff (new), Nine Hill Tuff (new), Eureka Canyon Tuff (new), and Santiago Canyon Tuff (new). Type locality is reassigned to Santiago Canyon Tuff.

Source: GNU records (USGS DDS-6; Menlo GNULEX).