Undivided metasedimentary, metavolcanic, and gneissic rocks. (1600-1800 Ma)

Metasedimentary rocks, mostly derived from sandstone and shale, with minor conglomerate and carbonate rock. Includes quartz-rich, mostly nonvolcanic Pinal Schist in southeastern Arizona and variably volcanic-lithic sedimentary rocks in the Yavapai and Tonto Basin supergroups in central Arizona. (1600-1800 Ma)

Weakly to strongly metamorphosed volcanic rocks. Protoliths include basalt, andesite, dacite, and rhyolite deposited as lava or tuff, related sedimentary rock, and shallow intrusive rock. These rocks, widely exposed in several belts in central Arizona, include metavolcanic rocks in the Yavapai and Tonto Basin supergroups. (1650 to 1800 Ma)

Sandstone and conglomerate derived from volcanic rocks with associated intermediate-composition lava flows, breccias, and tuffs. In southern Arizona this unit includes rocks of the Artesa sequence, Pitoikam Formation, Mulberry Wash volcanics, Rudolfo Red Beds, Recreation Red Beds, and Gardner Canyon Formation. In western Arizona it includes the Harquar Formation, rocks of Slumgullion, and related(?) unnamed units in the Kofa and Middle Mountains. This unit is characterized by maroon, brown, and purplish-gray volcanic-lithic sandstone and siltstone, with subordinate to abundant conglomerate, quartz-rich sandstone and sparse limestone. (150-170 Ma)

Highly faulted and folded rocks of units Jv, J_, and Pz, deformed and metamorphosed in Jurassic, Cretaceous and Tertiary time. This unit is restricted to west-central Arizona. (160-540 Ma)

Schists of various types; mostly Paleozoic or Mesozoic age; some Precambrian.

Schists of various types; mostly Paleozoic or Mesozoic age; some Precambrian.

Allingtown Metavolcanics plus Maltby Lakes Metavolcanics - Allingtown Metavolcanics - Green, fine-grained, massive greenstone, composed of epidote, actinolite, albite, and chlorite, commonly with abundant megacrysts of saussurite, interlayered with minor green phyllite, generally containing quartz and sericite. Dark amphibole in western outcrops. Maltby Lakes Metavolcanics - Green to gray-green, fine-grained, massive to well-foliated and layered greenstone, greenschist, and schist; also dark amphibolite to west and southwest.

Lower part [of Maltby Lakes Metavolcanics] - Gray-green to green, fine-grained, generally well foliated greenschist, greenstone, and schist or phyllite, composed of albite and chlorite, plus quartz and sericite or epidote and actinolite. Mixed metavolcanics and metasedimentary rocks.

Maltby Lakes Metavolcanics - Green to gray-green, fine-grained, massive to well-foliated and layered greenstone, greenschist, and schist; also dark amphibolite to west and southwest.

Upper part [of Maltby Lakes Metavolcanics] - Green to gray-green, fine-grained, layered and foliated to massive greenstone and greenschist, composed of epidote, albite, actinolite, and chlorite, and locally minor quartz, sericite, garnet, pyrite, or calcite. Mainly metavolcanic.

Lower Mesozoic intrusions; localized near the Snake Canyon of western Idaho.

Upper Triassic shale overlying reefal limestone and dolomite in west-central Idaho.

Jurassic marine wacke, volcanic, or carbonate metasediments of western Idaho.

Vaughn Hills Quartzite - Quartzite, phyllite, conglomerate, and chlorite schist.

Volcanic Complex of Cecil County - Metamorphosed andesitic and dacitic volcanic rocks (greenstone, greenschist, quartz amphibolite, and schistose felsite); amygdules and volcano-clastic textures locally preserved; thickness unknown.

Metabasalt - Sequence of conformably layered volcanic rocks of fine-grained to aphanitic, greenish-gray, retrogressively metamorphosed greenstone, greenschist, and basalt. Greenschist contains clots and lenses of blue quartz and abundant sulfide. Unit does not crop out and is known only from subsurface borings and artificial exposures. Interpreted to be Late Proterozoic by Volkert and Drake (1993) on the basis of geochemical similarity to Late Proterozoic metadiabase dikes in New Jersey Highlands.

Alkalic basalt, greenstone, and actinolite schist. Includes metamorphosed volcanoclastic rocks and iron-rich schist.

Orfordville Formation, Post Pond Volcanics - Greenstone, green chloritic schist interbedded with schistose felsite, quartz-feldspar-sericite schist; fine-grained chloritic, biotitic gneiss, all west of Ammonoosuc fault; mainly amphibolite east of the Ammonoosuc fault.

Orfordville Formation, Sunday Mountain Volcanics - Greenstone, chloritic schist, felsite, and quartz-feldspar-sericite schist.

Mostly homogenous schistose greenstone; in places massive, mottled, and containing conspicuous calcite and epidote. Tuffaceous chlorite schist in upper part in northern Pend Oreille County. Amphibolite and plagioclase amphibolite in Little Pend Oreille Lakes district. Massive to sheared or schistose greenstone with dark-green ovoid spots; agglomeratic and amygodaloidal in places; sheared pillows near Blue Creek, central Stevens County; minor intrusive phase and probable center of eruption west of Finch magnesite quarry; central to southwestern Stevens County.

Biotite, quartz diorite, trondhjemite, and hornblende gneisses, many of which are migmatitic; includes small granitic bodies locally. Small areas of mica schist, marble, amphibolite, and lime-silicate rocks in Entiat Mountains area of Chelan County.

Greenschist of central Whatcom and Skagit Counties.

Greenschist, phyllite, and slate; includes some limestone, quartzose phyllite, schistose metaconglomerate, breccia, and basic igneous rocks. Includes schist locally.

Schist, amphibolite, and minor lime-silicate rocks, marble, quartzite, and metaconglomerate.

Sedimentary and volcanic rocks, undivided. Graywacke, argillite, siltstone, slate, volcanic rocks, phyllite, greenschist, and greenstone.