DESCRIPTION OF MAP UNITS

The geologic map for the Craig and Dixon Entrance quadrangles, upon which this report is based, is simplified from the publications and maps cited in the CDE-Bibliography. All the major geologic units in those reports are represented in the map units used here or are used in the descriptions of the units that follow. However, certain units used here combine units used by previous workers, and their maps should be consulted for more detailed information. Those reports also include considerably more details about the petrology, structure, and ages of the rock units in the area.

SEDIMENTARY, METAMORPHIC, AND VOLCANIC ROCKS

Qtv	Extrusive volcanic rocks (Quaternary? and Tertiary)-- Mainly rhyolite to basalt in a variety of breccia bodies, tuff layers, flows, small plugs and dikes

MzPzm	Metamorphosed sedimentary, volcanic, and intrusive rocks (Mesozoic and (or) Paleozoic)--Dark gray phylllite and fine-grained semischist., greenschist facies metamorphosed andesite and basalt flows on southern Cleveland Peninsula; amphibolitic and quartzo-feldspathic schist and gneiss to north; and few small bodes of metamorphosed diorite, quartz diorite, and gabbro

Trh	Hyd Formation (Triassic)-- Polymictic breccia that consists of pebbleto boulder-sized clasts of a heterogeneous suite of plutonic, metamorphic, and sedimentary rocks; possibly a submarine talus deposit. Age enigmatic; alternatively, may be Devonian

|Pkl	Klawack Formation and Ladrones Limestone, undivided (Middle and Early Pennsylvanian)-- Klawack Formation consists mainly of sandstone and siltstone-, the Ladrones Limestone is massive limestone. Both locally contain chert pebbles and nodules

Mp	Peratrovich Formation (Late and Early Mississippian)-- Bedded limestone with chert nodules that gradationally overlies bedded chert

Dpsc	Port Refugio Formation (Devonian), St. Joseph Island VoIcanics (Devonian?), and Coronodos VoIcanics (Devonian)--Mainly graywacke, mudstone, siltstone, and shale rich in volcanic material, accompanied by basalt flows and fragmental basalt. Locally, includes fossiliferous limestone

Dw	Wadleigh Limestone (Late, Middle and Early Devonian)-- Massive to bedded limestone with minor argillaceous limestone and calcareous shale

Dk	Karheen Formation and related rocks (Middle? and Early Devonian)-- Mainly redbed- and turbidite-
facies sandstone, mudstone, shale, and polymictic conglomerate. Minor limestone. Scattered rhyolite and andesite flows, and small plugs of andesite, dacite, and diorite

DSs	Sedimentary rocks of the Staney Creek and Tuxekan Passage area (Early Devonian? and Late to Early Silurian)-- Limestone, sandstone, mudstone, and polymictic conglomerate in order of abundance

Sh	Heceta Limestone (Late to Early Silurian)-- Reef limestone with minor limestone breccia, mudstone, and polymictic conglomerate

SOd	Descon Formation and related rocks (Silurian and Ordovician)-- Volcanic graywacke, siltstone, and mudstone turbidites with interlayered volcanic breccia, extrusive domes, flows, and tuffs that consist mainly of andesite and basalt with some dacite and rhyolite. Includes the andesitic breccia of Luck Creek. On northern Prince of Wales Island, includes small area of the partly correlative Bay of Pillars Formation which consists mainly of graywacke and mudstone turbidites.

Wales Group (Early Cambrian and Late Proterozoic)-- Divided into:

Zwg	Greenstone, greenschist, black phyllite, quartz-sericite schist, meta-keratophyre, and greenschist- to amphibolite-facies schist and gneiss

Zwm	Marble

PLUTONIC IGNEOUS ROCKS

Tm	Migmatitic granitic rocks (Miocene and/or Oligocene)-- Heterogeneous suite of granitic rocks that vary in composition from granite to diorite and from migmatites to massive and unfoliated

Kg	Granitic plutonic rocks (Cretaceous)-- Mainly tonalite, diorite, quartz diorite, quartz monzodiorite, and quartz monzonite, with several bodies of gabbro

Zoned mafic-ultramafic complex of Union Bay (Early Cretaceous)-- Divided into:

Kugb	Gabbro

Kudp	Dunite, pyroxenite, and peridotite

Jp	Plutonic rocks (Middle Jurassic)-- Peralkaline granite of Bokan Mountain and syenite at Dora Bay

P|Psy	Syenite (Early Permian and Late Pennsylvanian)-- Syenite near Klawock and leucosyenite on Sukkwan Island

SOg	Granitic to rnafic plutonic and metarnorphic rocks (Late to Early Silurian and Late Ordovician)-- Heterogeneous unit that includes granite, syenite, quartz monzonite, leucodiorite, diorite, quartz diorite, gabbro, hornblendite, trondhjemite, and pyroxenite. Also includes correlative metamorphic rocks at Kendrick Bay that consist mainly of gneiss, schist, and amphibolite

Og	Granitic plutonic rocks (Late and Middle Ordovician)-- Mainly quartz diorite, granodiorite, leucogranodiorite, and quartz monzonite. Also includes small body of foliated metagabbro and metadiorite with minor metavolcanic and metasedimentary rocks on southern Prince of Wales Island

g	Foliated granitic to mafic plutonic rocks (Early Cambrian)-- Foliated quartz diorite, granodiorite, diorite, and gabbro