WASHINGTON DIVISION OF GEOLOGY AND EARTH RESOURCESRon Teissere, State GeologistDavid K. N orman, Assistant State GeologistGEOLOGIC MAP OF WASHINGTON STATEby J. Eric SchusterWASHINGTON DIVISION OF GEOLOGY AND EARTH RESOURCESGEOLOGIC MAP GM-532005Envelope illustration: Shaded-relief map of Washington StateProject cartographers: J. Eric Schuster and Charles G. CaruthersPro je c t e di t or s: K atherine M. Reed and Jaretta M. RoloffProject designer: Jaretta M. RoloffSpecial thanks to Don Hiller of the Washington Depar tment of Natural Resources,Resource Mapping Division, for car tographic consultation.Disclaimer: This product is provided ‘as is’ without warranty of any kind, either expressed or implied, including, butnot limited to, the implied warranties of merchantability and fitness for a particular use. The Washington Departmentof Natural Resources will not be liable to the user of this product for any activity involving the product with respect tothe following: (a) lost profi ts, lost savings, or any other consequential damages; (b) the fitness of the product for a par-ticular purpose; or (c) use of the product or results obtained from use of the product. This product is considered to beexempt from the Geologist Licensing Act [RCW 18.220.190 (4)] because it is geological research conducted by theState of Washington, Department of Natural Resources, Division of Geology and Ear th Resources.This report was p roduced by:Washington Depar tment of Natural ResourcesDivision of Geology and Earth ResourcesPO Box 47007Olympia, WA 98504-7007E-mail: [email protected]: http://www.dnr.wa.gov/geology/This repor t is available online at:http://www.dnr.wa.gov/geology/Printed copies of this report are available from:Washington State Department of PrintingPO Box 798, MS 47100Olympia, WA 98507-0798Phone: 360-570-5555Fax: 360-586-8831TTD: 360-570-5069Website: http://www.prt.wa.gov/Printed in the United States of AmericaPamphlet printed on recycled stockiiCONTENTSMapcompilationandproduction.................................1Descriptionsofmapunits ....................................1Unconsolidatedsediments...................................1Sedimentaryrocksanddeposits ................................2Volcanicrocksanddeposits ..................................3Intrusiverocks.........................................5Metasedimentaryandmetavolcanicrocks............................7Metamorphicrocks(amphibolitefaciesandhigher).......................9Tectoniczones........................................10References cited ........................................10FIGURE AND TABLESFigure 1. Index map to 1:100,000-scale quadrangles in Washington State .............ivTable 1. List of map units showing 1:250,000-scale unitsincluded in each 1:500,000-scale unit .........................12Table2. Listofnamedunits..................................17PLATEGeologic map of Washington State and key to geologic unitsiiiiv1:250,000-scale mapsFigure 1. 1:100,000-scale Geologic Maps of Washington119°47°15¢120°30¢020 30 40050403010102060mikmColvilleRocheHarborPortAngelesMountOlympus124°123°122°121°118°117°49°48°30¢48°47°30¢47°46°30¢46°IlwacoOmakCouleeDamBanksLakeRitzvilleConnellWalla WallaHoodRiverHermiston119°120°118°117°49°125°124°125°48°30¢48°47°30¢47°46°30¢46°123°122°121°120°45°30¢CapeFlatteryChewelahSpokaneRosaliaPullmanMosesLakeRichlandRepublicNespelemOrovilleRobinsonMtnChelanWenatcheeMountRainierSnoqualmiePassSkykomishRiverSaukRiverMountBakerBellinghamSeattleMountSt. H elensVancouverWestportChehalisRiverPriestRapidsYakimaCopalisBeachCANADAUSAClarkston(and Orofino)OREGONCANADAIDAHOUSAForksMountAdamsCentraliaAstoriaPortTownsendTwispTacomaSheltonToppenishGoldendaleSW QUADNW QUADSE QUADNE QUADGEOLOGIC MAP OF WASHINGTON STATEby J. Eric SchusterMAP COMPILATION AND PRODUCTIONThe 1:500,000-scale geologic map of Washingtonwas compiled entirely from the preceding 1:250,000-scalegeologic quadrant maps of Washington (Fig. 1) (Walshand others, 1987; Stoffel and others, 1991; Schuster andothers, 1997; Dragovich and others, 2002). The level ofdetail was simplified by combining the 1:250,000-scalemap units into 1:500,000-scale map units that havebroader lithologic and age ranges and by deleting smalllakes and small poly gons of unconsolidated sedimentar ymap units. Table 1 (p. 12) shows which 1:250,000 unitsmake up each of the 1:500,000 units. The reader will no-tice that a few 1:250,000 map units listed in Table 1do not fit entirely within the age range or lithologicrange of the 1:500,000 unit. This was done to avoid1:500,000 units with very limited extents and to reducethe number of 1:500,000 units. Typically, a 1:250,000unit that does not fit was lumped with an appropriate1:500,000 lithologic unit, but its age extends outside therange of the 1:500,000 unit. Also, typically, the ‘young’end of the age range of the 1:250,000 unit fits within theage range of the 1:500,000 unit, but the ‘old’ end extendsbeyond the age range of the 1:500,000 unit. For example,1:500,000 unitƒmt includes 1:250,000 unit pTog (NE),which extends into the Precambrian, and unit pTog (NW),which extends into the Paleozoic. Although the map unitshave been simplified for presentation at 1:500,000 scale,the faults, folds, dikes, and eruptive centers generallyhave not. In complex, crowded areas some folds andsome or naments that identify fault types were omitted topreserve legibility.The 1:250,000-scale quadrant maps cited abovewere, in tur n, compiled mostly from 1:100,000-scale geo-logic maps (Fig. 1) compiled by geologists of the Washing-ton Division of Geology and Earth Resources or theU.S. Geological Survey. The 1:100,000-scale maps arereferenced in the pamphlets that accompany the1:250,000-scale quadrant maps. The 1:100,000-scalequadrangle index map (Fig. 1) and lines of latitude andlongitude on the 1:500,000-scale geologic map plate areincluded as an aid to readers who wish to be able to iden-tify which 1:100,000-scale quadrangle(s) contain a geo-logic feature of interest.Small index maps of the State of Washington accom-pany each of the map unit symbols and brief descriptionsin the ‘Key to Geologic Units’ on the plate. Each indexmap ser ves two purposes: it shows the color of the mapunit, and it shows the distribution of the unit. Showing thedistribution of each map unit this way is an idea borr owedfrom the Pennsylvania geologic map (Miles, 2003), but us-ing the index map to show the