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Geologic units containing pumice

California

Recent (Holocene) pyroclastic and volcanic mudflow deposits, unit 1 (Cascade Volcanic Field) (Holocene)

Recent (Holocene) pyroclastic and volcanic mudflow deposits; in part Pleistocene.

Recent (Holocene) pyroclastic and volcanic mudflow deposits, unit 2 (Mono Craters) (Holocene)

Recent (Holocene) pyroclastic and volcanic mudflow deposits; in part Pleistocene.

Idaho

Basalt, clay, and pumice; Late Pleistocene basalt flows, volcaniclastic debris, and ponded sediments of subunit 4b; Snake River Plain; (Late Pleistocene)

Upper Pleistocene Snake Plain basaltic lava flows, unit 4.

Basalt flows, pumice, and tuff; Early Pleistocene to Pliocene basaltic volcanics; Snake River Plain (Early Pleistocene)

Lower Pleistocene to Pliocene basalts with associated tuffs and volcanic detritus.

Basalt, gravel, and pumice; Late Pleistocene basaltic volcanics and interlayered sedimetnsof subunit 3b; Snake River Plain (Late Pleistocene)

Upper Pleistocene Snake Plain basaltic lava flows, unit 3.

Basalt, pumice; Holocene basaltic lava flows and cinder cones; Snake River Plain and vicinity (Holocene)

Recent, relatively unweathered Snake Plain basalt flows and cinder cones.

New Mexico

Bandelier Tuff (Phanerozoic | Cenozoic | Quaternary)

Bandelier Tuff; Jemez Mountains area only

Oregon

Tuffaceous sedimentary rocks and tuff (Pliocene and Miocene) (Miocene to Pliocene)

Semiconsolidated to well-consolidated mostly lacustrine tuffaceous sandstone, siltstone, mudstone, concretionary claystone, conglomerate, pumicite, diatomite, air-fall and water-deposited vitric ash, palagonitic tuff and tuff breccia, and fluvial sandstone and conglomerate. Palagonitic tuff and breccia grade laterally into altered and unaltered basalt flows of unit Tob. In places includes layers of fluvial conglomerate and, in parts of the Deschutes-Umatilla Plateau, extensive deposits of fanglomerate composed mostly of Miocene basalt debris and silt. Also includes thin, welded and nonwelded ash-flow tuffs. Vertebrate and plant fossils indicate rocks of unit are mostly of Clarendonian and Hemphillian (late Miocene and Pliocene) age. Potassium-argon ages on interbedded basalt flows and ash-flow tuffs range from about 4 to 10 Ma. Includes the Drewsey Formation of Shotwell and others (1963); sedimentary parts of the Rattlesnake Formation of Brown and Thayer (1966); an interstratified ash-flow tuff has been radiometrically dated by potassium-argon methods at about 6.6 Ma (see Fiebelkorn and others, 1983); Bully Creek Formation of Kittleman and others (1967); Dalles Formation of Newcomb (1966, 1969); Shutler Formation of Hodge (1932), McKay beds of Hogenson (1964) and Newcomb (1966) (see also Shotwell, 1956); Kern Basin Formation of Corcoran and others (1962); Rome beds of Baldwin (1976); parts of the (now obsolete) Danforth Formation of Piper and others (1939), Idaho Group of Malde and Powers (1962), Thousand Creek Beds of Merriam (1910); the Madras (or Deschutes) Formation, the "Simtustus formation" of Smith (1984), and the Yonna Formation (Newcomb, 1958). In areas west of Cascade crest, includes the Sandy River Mudstone and the Troutdale Formation of Trimble (1963) and the lower Pliocene Helvetia Formation of Schlicker and Deacon (1967)

Tuffaceous sedimentary rocks and tuffs (lower? Pleistocene or Pliocene) (Pliocene to Early Pleistocene)

Rhyolitic to andesitic ash-flow tuffs, pumice-fall deposits, minor mud flows, and older alluvium on the flanks of Newberry volcano (MacLeod and others, 1981; 1982) and in areas west and northwest of Bend

Washington

Miocene-Pliocene nonmarine rocks (Miocene-Pliocene)

Tuffaceous and pumiceous andesitic sandstone and siltstone with interbedded conglomerate and claystone. Conglomerate beds chiefly andesitic, but also quartzitic, granitic, and basaltic; includes basalt flows locally.

Miocene-Pliocene volcanic rocks (Miocene-Pliocene)

Dark-gray, fine-grained, dense, porphyritic in part, basalt flows in central and south-central part of State; commonly interbedded with conglomerate, sandstone, and siltstone. Includes small areas of rhyolite north of Cle Elum in Kittitas County, and andesite north of Leavenworth in Chelan County.