U.S. Department of the Interior Scientific Investigations Map 3315 U.S. Geological Survey Prepared in cooperation with the Sheet 3 of 3 Water Resources Program of the Yakama Nation Pamphlet accompanies map CORRELATION OF MAP UNITS LIST OF MAP UNITS bth Basalt of Toppenish Ridge (early Pleistocene) [Radioisotopic ages (ka) shown for dated units, rounded from table 1. Stipple indicates units partly [Stipple indicates partly or wholly pyroclastic. See DESCRIPTION OF MAP UNITS for specific age unit or wholly pyroclastic. See DESCRIPTION OF MAP UNITS for specific unit age assignments] btn Basalt north of Trout Creek (Pliocene) assignments] btp Trachybasalt of Toppenish Creek (Pliocene) AGE SURFICIAL DEPOSITS VOLCANIC ROCKS SURFICIAL DEPOSITS AND BASEMENT ROCKS btr Basalt of Trout Creek (Pliocene) al Alluvium and silt deposits (Holocene) WESTERN SWATH EASTERN PLATEAUS bts Trachybasalt south of Toppenish Ridge (early Pleistocene) SWATH OF LESSER VENT DENSITY CENTRAL SWATH OF HIGH VENT DENSITY SIMCOE MOUNTAINS HIGHLAND oal Older alluvium (Holocene and Pleistocene) btw Basalt west of Tannawasha Pasture (Pliocene) cl Colluvium and talus (Holocene and Pleistocene) bub Trachybasalt of upper Blue Creek (early Pleistocene) ls Landslide deposits (Holocene and Pleistocene) bus Basalt of upper Sheep Creek (early Pleistocene) al Holocene Tcr Columbia River Basalt Group (Miocene) but Trachybasalt of upper Twentyfive Mile Creek (early Pleistocene or Pliocene) VOLCANIC ROCKS buw Trachybasalt of upper White Creek (Pliocene) 10 ka [Listed alphabetically by three-letter map-unit label] cl ls aec Trachyandesite east of Castle Rock (Pliocene) bw Basalt and trachybasalt of White Creek (early Pleistocene) apc Trachyandesite of Parrott Crossing (late Pleistocene) bwb Basalt of Wellenbrock Spring (Pliocene) bgb 68±10 bwc oal Late Pleistocene asi Trachyandesite of Simon Butte (early Pleistocene) bwc' Basalt of Wilson Charley Canyon Road (Pliocene) awv Trachyandesite west of Vessey Springs (early Pleistocene) bwd Trachybasalt of White Deer Road (early Pleistocene or Pliocene) ayc Trachyandesite of Yatama Creek (Pliocene) bwe Basaltic trachyandesite east of White Creek (Pliocene) apc 120±5 126 ka a72 Trachyandesite of Cone 3972 (Pliocene) bwf Basalt west of White Fir Creek (early Pleistocene) a72' Photograph showing stack of four thin Simcoe lava flows on east rim of Klickitat River gorge, midway between bbc Trachybasalt of Bowman Creek divide (middle or early Pleistocene) bwg Basalt west of Garner Camp (Pliocene) its White Creek and Summit Creek tributaries (fig. 3). Nearly aphyric flows, each 8–20 m thick, are mapped as bfc 681±2 trachybasalt of Schafer Creek (3.25 Ma); they flowed southwest across low-relief surface of Miocene Colum- bbe Trachybasalt east of Bear Creek (early Pleistocene or Pliocene) bwh Trachybasalt of White Deer Creek (Pliocene) bia River Basalt Group. Simcoe lavas commonly form relatively thin rimrock stacks atop Columbia River Basalt Middle Pleistocene bcd bps 631±27 Group. Viewed northeastward in image, 50–70 m of Simcoe lavas rest on 250-m-thick exposure of Columbia bbl Trachybasalt of Blue Creek (early Pleistocene) bwi Trachybasalt of West Indian Rock (Pliocene) River Basalt Group, which here includes several members of Wanapum and Saddle Mountains Basalts (Bentley 674±4 byt bkb 688±25 b58 700±30 and others, 1980). bbw Basalt west of Bergie Springs (Pliocene) bwk Trachybasalt west of West Fork White Creek (early Pleistocene) bnk bcc Trachybasalt of Clock Creek (early Pleistocene or Pliocene) bwl Trachybasalt of Wall Canyon (early Pleistocene) Middle or Early bms b10 781 ka bbc byc Pleistocene bcd Trachybasalt of Cedar Creek (middle Pleistocene) bwp Basalt west of Poker Spring (early Pleistocene) 776±2 bsl bcf Trachybasalt of South Fork Camp (early Pleistocene) bwr Trachybasalt and basaltic trachyandesite of West Road (Pliocene) bof 967±4 bcl Trachybasalt of Campbell Line (Pliocene) bws Trachybasalt west of Stagman Butte (early Pleistocene) bpb' bpb 822±3 boh 981±14 blc bcp Trachybasalt of cinder pits west of Vessey Springs (early Pleistocene) bwt Trachybasalt west of Toppenish Creek (Pliocene) brs bpo 1,101±3 bcr bww' bww Basalt west of Wilson Charley Canyon (early Pleistocene or Pliocene) bcr' Trachybasalt of Coyote Springs Road (early Pleistocene) bcs Basalt of Camas Patch (early Pleistocene) bxc Trachybasalt of Section Corner Creek (early Pleistocene or Pliocene) bcv byc Trachybasalt of Yeackel Camp (middle or early Pleistocene) bcv' Trachybasalt of Cedar Valley Road (early Pleistocene) bhb4 bcw Basalt west of Castle Rock (Pliocene) bys Basalt of South Fork Yatama Creek (Pliocene) bhb3 byt Trachybasalt of Yatama Creek (middle Pleistocene) bhb2 bcx Trachybasalt of Castle Rock (Pliocene) bhb1 bnw bc2 b00 Trachybasalt of Cone 3600 (early Pleistocene) b30 1,276±5 bcp Trachybasalt of Cone 3572 (early Pleistocene) bc5' bc5 Trachybasalt of Cone 3895 (early Pleistocene) b01 Trachybasalt of Cone 3801 (Pliocene) bsn bc6 Trachybasalt of Cone 3606 (early Pleistocene) b03 Basalt of Cone 4003 (early Pleistocene) bjb 1,350±50 bss bws 1,479±4 bnf 1,533±3 bc8 Trachybasalt of Cone 3580 (early Pleistocene) b10 Trachybasalt of Cone 3010 (middle or early Pleistocene) bdf Trachybasalt of Dry Creek Falls (early Pleistocene) b14 Basalt of Shield 3114 (Pliocene) b85 b03 b29 1,420±4 bdl Basalt of Delaney Spring (Pliocene) b22 Basalt of Cone 3122 (early Pleistocene) bmf b23 bcr bdr Trachybasalt of Deer Creek (early Pleistocene or Pliocene) Basalt of Cone 2823 (early Pleistocene or Pliocene) bcv 1,513±4 bgs bcv' bcr' mws 1,531±5 bds b27 Basalt of Cone 2784 (early Pleistocene or Pliocene) bds' Trachybasalt south of Dry Creek (early Pleistocene or Pliocene) mes b63 beb Basalt east of Bowman Creek (Pliocene) b29 Basalt and trachybasalt of Hill 2946 (early Pleistocene) Photograph showing intracanyon stack of thin lava flows mapped as basalt of Outlet Falls (0.97 Ma), viewed bsb northward at confluence of Outlet Creek and Klickitat River gorge. At left, 100-m-thick stack of >30 flows rests bec Trachybasalt of Elk Creek (Pliocene) b30 Trachybasalt of Cone 3066 (early Pleistocene) QUARTERNARY on Miocene Columbia River Basalt Group (beneath talus) and supports extensive low-relief plateau above rim. bst At right, beyond Klickitat River and River Route Road, low amphitheater is landslide complex at Borde Flats, b31 Basalt of Cone 3185 (early Pleistocene) bem Trachybasalt east of McKays Butte (early Pleistocene) above which rimrock is basalt of Pole Creek Road (3.3 Ma). bus beo Trachybasalt east of Olney Creek (early Pleistocene) b32 Trachybasalt of Cone 3632 (early Pleistocene) b37 bnt bes Trachybasalt east of Schafer Creek (early Pleistocene) b33 Trachybasalt of Cone 3303 (early Pleistocene) 1,328±2? bnb bew Basalt east of White Creek (Pliocene) b34 Trachybasalt of Cone 3401 (early Pleistocene) mnb bns' bns b36 bes b46 b32 bhs 1,566±3 b36' b36 bfc Trachybasalt of Featherbed Creek (middle Pleistocene) b36' Trachybasalt of Road Junction 3666 (early Pleistocene) b33 bfr Feldspar-rich trachybasalt north and south of Smith Butte (Pliocene) b37 Trachybasalt of Shield 3794 (early Pleistocene) bwf bly 1,697±20 1,687±5 bbl bub m93 bgb Basalt of Glaciate Butte (late Pleistocene) b39 Basalt of Cone 3963 (early Pleistocene) b34 bwk bsr 1,685±11 t39 b90 Early Pleistocene bgp b41 Trachybasalt of Crag 3541 (Pliocene) b94 bs 1,722±5 Basalt of Spring Creek gravel pit (early Pleistocene) asi b39 bgs b46 Trachybasalt of Cone 3346 (early Pleistocene) b97 b62 Trachybasalt of Graham Spring (early Pleistocene) 1,675±5 bsc X mtc bem b00 bhb1 bhb2 Trachybasalt of Hagerty Butte (early Pleistocene) b47 Basalt of Cone 5147 (early Pleistocene or Pliocene) bkl 1,748±5; 1,740±2 bhb3 bhb4 b52 Basalt of Knob 5268 (Pliocene) 1,875±3 bsi bop b73 bhf b73' Trachybasalt of Hoppers Flat (early Pleistocene or Pliocene) b58 Trachybasalt of Cone 5822 (middle Pleistocene) bsw 2,060±10 bsf bhs Trachybasalt of Hog Swamp (early Pleistocene) b59 Basalt and trachybasalt of Cone 5659 (Pliocene) 1,609±2 b31 bcs b22 bw 1,885±5 1,882±17 bht Trachybasalt at Tepee Creek headwaters (early Pleistocene or Pliocene) b60 Basalt of Cone 3560 (early Pleistocene) bsd b76 btc bc5' bc5 bhw Basalt at White Fir Creek headwaters (early Pleistocene or Pliocene) b62 Trachybasalt of Cone 2862 (early Pleistocene) bcf mns bix Basalt of IXL Crossing Road (early Pleistocene or Pliocene) b63 Trachybasalt of Cone 2763 (early Pleistocene) bgp bjb Basalt of Jungle Butte (early Pleistocene) b65 Trachybasalt of Cone 2865 (Pliocene) bjs bsu Trachybasalt of Jungle Spring (Pliocene) b66 Trachybasalt of Cone 2663 (early Pleistocene or Pliocene) bkb Trachybasalt of Kaiser Butte (middle Pleistocene) b68 Basalt of Shield 2368 (early Pleistocene or Pliocene) bwl bdf Photograph showing semi-arid plateaus typical of northeast part of Simcoe Mountains volcanic field. View southwestward upstream along Logy Creek near confluence of Spring Creek (at right). Gorge of Logy Creek is b73 bkc Trachybasalt of Kusshi Creek (early Pleistocene or Pliocene) Basalt and trachybasalt of Cone 2873 (early Pleistocene) ~130 m deep, walled mostly by Miocene Columbia River Basalt Group. Numerous ledges low on gorge walls and beo bsm' bsm 2,056±25 b73' in foreground are remnants of intracanyon lava flows of trachybasalt of Yatama Creek (~674 ka), one of bkl Trachybasalt of Klose Butte (early Pleistocene) b76 Trachybasalt of Cone 3176 (early Pleistocene) youngest units in volcanic field. Thin rimrocks on both sides of gorge are lava flows of basalt of South Fork bts bor 2,079±6 bmb