IDAHO GEOLOGICAL SURVEY DIGITAL WEB MAP 87 MOSCOW-BOISE-POCATELLO KAUFFMAN AND OTHERS

GEOLOGIC MAP OF THE FENN QUADRANGLE, IDAHO COUNTY, IDAHO CORRELATION OF MAP UNITS Disclaimer: This Digital Web Map is an informal report and may be revised and formally published at a later time. Its content and format Artificial Alluvial Mass Movement Intrusive Volcanic Rocks Island-Arc Metavolcanic Deposits Deposits Deposits and Metasedimentary Rocks John D. Kauffman, Keegan L. Schmidt, Dean L. Garwood, and Kurt L. Othberg may not conform to agency standards. Rocks m Qam Qaf 2007 Qas Holocene Qamo Qls Qt Qafo QUATERNARY Qag Pleistocene 02DG023 Columbia River Basalt Group 80 Tgn1 Tgv 02DG024 Saddle Mountains Basalt 02DG022 VC79-410 Tgv Tgn1 Tgn Qaf 1 Tgv 02DG021 Qas Grande Ronde Basalt 5 CENOZOIC A Tgr2 Tli Miocene TERTIARY FAULT Tgn1 Tgbd

Tgn 02DG043 Tgr1 1 Tgv Tgr 2? Tgv 1

Imnaha Basalt Tgv 02DG020 Tim Tgr2 Tgv

CREEK KJap CRETACEOUS Seven Devils Group Tgr2 JURASSIC MESOZOIC Qafo TRIASSIC TRPsd 02DG044 Tgv PERMIAN PALEOZOIC

Qas Qas 02DG019 Qas

GRAVE Tgr2 INTRODUCTION magnetostratigraphic units (Swanson and others, 1979). Of these units, flows SYMBOLS m of the R , N and R are exposed in the quadrangle. No Wanapum Basalt 02DG018 Tgn1 1 1 2 units occur in the quadrangle. A single flow of Saddle Mountains Basalt, the The geologic map of the Fenn quadrangle depicts rock units exposed at the 80 Contact: Line showing the approximate boundary between one Tgr ? Qaf 2 surface or underlying thin surficial cover of soil and colluvium. Thicker basalt of Grangeville, forms a thin cap on Grande Ronde Basalt units on the map unit and another. surficial deposits of alluvium and landslide deposits are also depicted where plateau surface. Basalt units were identified using hand sample characteristics, Qaf Tgr2 A’ they mask or modify the underlying rock units or form significant mappable paleomagnetic signatures, geochemical signatures, and compilation of Fault, approximately located; dotted where concealed; bar and 02DG042 Tgv units. The map is the result of field work conducted in 2002 and 2006 by previous data. Representative samples of most basalt units were collected ball on downthrown side; arrow indicates dip of fault. the authors and compilation from previous work, including that of Bond for chemical analysis. These samples supplement previous ones collected (1963) and reconnaissance mapping and sampling in the area from 1978 by V. E. Camp (written commun., 2002). Our sample locations and those to 1980 (Camp, 1981; Swanson and others, 1981). of Camp are identified on the map. Analytical results are listed in Table 1. Qas Fold axis, approximately located; dotted where concealed; arrow Samples were analyzed at Washington State University’s GeoAnalytical indicates direction of plunge. Tgv The quadrangle is mostly underlain by Miocene basalt flows of the Columbia Laboratory. River Basalt Group. Exposures of prebasalt rocks are restricted to the Salmon Qls 02DG017 River canyon in the south part of the quadrangle and consist of Permian to Saddle Mountains Basalt Anticline. Triassic island-arc rocks of the Seven Devils Group, including metamorphosed Basalt of Grangeville (Miocene)–Medium to dark gray, fine- to medium- volcanic flows, sediments, and intrusive units. The island-arc rocks were Tgv Monocline, synclinal flexure; shorter arrow on steeper limb. grained basalt with common plagioclase phenocrysts 1-4 mm in length and accreted to the North American continent during the Jurassic to Cretaceous 06JK004 scarce to common olivine grains generally <1 mm in diameter that tend to Syncline. Tgv and were later intruded by aplitic dikes, probably in the late Jurassic or Tgbd m weather pinkish or orangish. Reverse magnetic polarity as determined in the 02DG016 Cretaceous. Prior to eruption of the Columbia River Basalt Group, the land field and the laboratory. Consists of one flow ranging from about 30-80 feet Tgn1 mass was eroded to form steep, rugged topography. During the Miocene, Estimated strike and dip of bedding or volcanic flow. thick. Forms the capping unit along the rim of Rock Creek canyon. Pinches the basalts were erupted from linear vents south and west of the quadrangle. Tgbd out northward just beyond the northern edge of the quadrangle. Probably m The flows invaded the area, filling the irregular topography and covering the Horizontal basalt flow. Qaf filled a broad flat synclinal trough and was restricted to the east side of Grave Tgr 2? older rocks. Near the contact of the basalt and the older rocks, discontinuous 02DG015 Creek by the Grave Creek fault and monocline and to the north side of the Strike and dip of bedding or volcanic flow. sediments were deposited and later were covered by subsequent basalt Salmon River by anticlinal and monoclinal flexures. Equivalent to the flows, forming interbeds within the basalt sequence. Structural warping of Tgr2 Grangeville Member of Camp (1981) and the Amphitheater flow of Bard the basalt occurred both during and after emplacement, in part controlling (1978). the distribution of younger basalt units, steam development, and the cutting Strike of vertical cleavage. 06JK050 of the Salmon River canyon and Rock Creek canyon (also called Rocky Swanson and others (1981) note a feeder dike for the Grangeville unit in 02DG014 Canyon). The Grave Creek fault in the northwest part of the quadrangle Von Berge Gulch and cite “P. Hooper, C. Knowles, and J. Bond, oral Tgr2 developed after extrusion of Grande Ronde R2 basalt and prior to extrusion communication,” as the reference. Recent communications with Peter Hooper of the basalt of Grangeville. Vertical displacement along this segment of the and Charles Knowles indicate the dike in question probably is not a Grangeville fault is about 200 feet. Landslides primarily occur where a thick weathered dike. A breccia dike (Tgbd) sampled at the location noted on Swanson and Headwall scarp of landslide. zone in basalt and thin Miocene sediments are exposed in the upper slopes others’ map has Grande Ronde chemistry (sample 06JK058; Table 1). We 2 of Rocky Canyon. The plateau soils include loess parent material (Barker, suspect a cartographic error, wherein a “Tgr” (for Grande Ronde) label may 1982), but loess deposits are thin and not included on this map. In addition Qaf have been misinterpreted as a “Tgv” (Grangeville) label when their map was 02DG013 to its present channel, Salmon River alluvial deposits form terrace remnants compiled. No source dike for the basalt of Grangeville was found during Qaf Tgv of at least two older regimes of the river. this project. Tgr1 Closed or nearly closed topographic depression in surface of Qaf Qag Tgb Qaf d basalt. 06JK058 DESCRIPTION OF MAP UNITS Grande Ronde Basalt 02DG012 Qafo Qas Qas Tgr2 Tgr2 Grande Ronde R2 magnetostratigraphic unit (Miocene)–Medium to dark Tim Tgr1 Tgn ARTIFICIAL DEPOSITS Qaf 1 Qls gray, fine-grained basalt, commonly with a sugary texture. Uncommon to common plagioclase phenocrysts 1-2 mm long. Reverse magnetic polarity, Qls Tli m Made ground (Holocene)–Artificial fills composed of excavated, transported, Sample location and number. Qaf although field magnetometer readings commonly give weak normal or Qls Tgn1 and emplaced construction materials of highly varying composition, but Tgr1 conflicting results, particularly near the top of the R section. Unit consists Tim Qaf 06JK062 typically derived from local sources. 2 06JK023 of one to three flows and thins from west to east and pinches out in the Tgr2 SEDIMENTARY AND northeast corner of the quadrangle. Thickness on the east rim of Grave Creek Tgbd canyon is about 200-250 feet. Thins eastward to about 40 feet before pinching Qas Tgr2 MASS MOVEMENT DEPOSITS out near Meyer Gulch in upper Rock Greek.

Tgbd Alluvial Deposits Qls Qls Tgn1 Grande Ronde N1 magnetostratigraphic unit (Miocene)–Dark gray, fine- Qls grained generally aphyric to plagioclase microphyric basalt. Normal magnetic Alluvium of the Salmon River (late Holocene)–Channel and flood-plain deposits Qam polarity. Consists of four to six flows (possibly some with multiple “flow Qaf that are part of the present river system. Two grain-size suites are typically units”) with a total thickness of 800-900 feet. Well exposed in the canyons present: well-sorted and rounded pebble to boulder gravel in river bars and ACKNOWLEDGMENTS of Rock Creek and Salmon River. Individual flows range from 50 feet to more islands, and coarse sand in thin shoreline deposits. Gravel includes clasts Tgr1 than 150 feet thick. Flows near the top of the sequence are commonly 50- Tgn of primarily basaltic and metamorphic rocks. We thank the many landowners in the area for access to their property. V.E. 1 70 feet thick and typically sugary textured with scarce small plagioclase Camp provided copies of his field notes and map of the area and gave Qls phenocrysts 1-3 mm in length. Flows lower in the sequence, such as the Tgr Qamo Older alluvium of the Salmon River (early Holocene)–Primarily stratified sand permission to publish his sample analytical results. We would like to thank 2 Johns Creek flow of Bond (1963), are typically thicker, generally 100-200 Qaf and well-rounded pebble to boulder gravel of point-bar and terrace remnants Peter Hooper and Charles Knowles for their input regarding the Grande that are above modern levels of the Salmon River. Gravel clast lithology feet. Tgn1 Qas Ronde dike in Von Berge Gulch that was previously mapped as basalt of Tgv similar to Qam. May be capped by thin loess and eolian sand. Height above Grangeville. Tgr Grande Ronde R1 magnetostratigraphic unit (Miocene)–Mostly dark gray, present mean water level is approximately 40 feet. Interfingers with colluvium 1 B’ fine-grained aphyric to microphyric basalt. Very rare plagioclase phenocrysts and alluvial-fan deposits at toe of canyon slope. Thickness 5-20 feet. 2-4 mm in length in one or more flows. The informal Rogersburg unit (Reidel Qls and others, 1989) has common to abundant plagioclase phenocrysts 2-8 Qls Qag High terrace gravel of the Salmon River (Pleistocene)–Stratified sand and well- mm in length and is well exposed in lower Grave Creek. Reverse magnetic REFERENCES Qls rounded pebble to boulder gravel that form terrace remnants 60-100 feet Qls above present mean water level. Gravel clast lithology similar to Qam. polarity, although flows near the R1-N1 boundary commonly have inconsistent Barker, R.J., 1982, Soil survey of Idaho County area, western part: U.S. Department Qls Tgr2 Commonly capped by local colluvium, alluvial-fan deposits, or thin loess. and weak field magnetometer polarity readings; therefore the mapped contact of Agriculture, Soil Conservation Service, 266 p., 79 plates. Thickness 5-20 feet is poorly constrained. In general, the contact occurs between the Johns Creek and Center Creek flows of Bond (1963), which both have thick, tiered Bard, C.S., 1978, Mineralogy and chemistry of pyroxenes from the Imnaha and Tgv lower Yakima basalts of west-central Idaho: Washington State University Tgv Qas Channel and flood-plain deposits of Rock Creek and Grave Creek; and upland entablatures, and are usually separated by one or two thin flows. Outcrop M.S. thesis, 75 p. Qls alluvial deposits in drainageways (Holocene)–Primarily stratified and rounded characteristics of flows are similar to those in the Grande Ronde N1 unit. Tgv pebble to boulder gravel in Rock Creek and Grave Creek; and stratified silt, Consists of about five to seven flows with a total thickness of 600-700 feet. Bond, J.G., 1963, Geology of the Clearwater embayment: Idaho Bureau of Mines sand, and clay with minor intercalated subrounded to angular gravel in local and Geology Pamphlet 128, 83 p. upland drainageways. Gravel clasts predominantly basalt. Tgbd Grande Ronde breccia dikes (Miocene)–Several breccia dikes occur in Camp, V.E., 1981, Geologic studies of the Columbia Plateau: Part II. Upper Grande Ronde basalt. These features do not appear to be sheared, fault Miocene basalt distribution, reflecting source locations, tectonism, and Qaf Alluvial-fan deposits (Holocene)–Crudely bedded, poorly sorted brown muddy breccias, but rather consist of welded angular fist-size and smaller fragments; drainage history in the Clearwater embayment, Idaho: Geological Society Tgr 2 2 gravel derived from basalt colluvium on steep canyon slopes. Gravel is they do not exhibit the typical horizontal jointing common to most feeder of America Bulletin, Part I, v. 92, p. 669-678. composed of subangular and angular pebbles, cobbles, and boulders of dikes. The dikes form vertical ribs on slopes because of their resistance to Reidel, S.P., T.L. Tolan, P.R. Hooper, M.H. Beeson, K.R. Fecht, R.D. Bentley, and 2 Tgv basalt in a matrix of granules, sand, silt, and clay. May include beds of silt weathering. Two adjacent dikes are located on the east slope above Grave J.L. Anderson, 1989, The Grande Ronde Basalt, Columbia River Basalt Group; and sand reworked from loess and Mazama ash. Thickness highly variable, Creek and several parallel dikes are in Rock Creek and tributary Von Berge stratigraphic descriptions and correlations in Washington, Oregon, and ranging 5-50 feet. Gulch. The dikes on Grave Creek and Von Berge Gulch terminate near the Idaho, in S.P. Reidel and P.R. Hooper, eds., Volcanism and Tectonism in the top of a thick flow in Tgn1 (the Johns Creek flow of Bond, 1963). The dikes Columbia River Flood-Basalt Province: Geological Society of America Special Qafo Older alluvial-fan deposits (late Pleistocene to early Holocene)–Poorly sorted in Rock Creek are on strike with the Von Berge Gulch dike and probably Paper 239, p. 21-53. gravel deposits of incised alluvial fan remnants. Texture and lithology similar are related, but erosion has removed their upper part; where exposed, they Swanson, D.A., J.L. Anderson, V.E. Camp, P.R. Hooper, W.H. Taubeneck, and to Qaf. Thickness highly variable, ranging 10-50 feet. cut Grande Ronde R1 flows. Samples of the dikes have Grande Ronde T.L. Wright, 1981, Reconnaissance geologic map of the Columbia River chemistry (Table 1). Basalt Group, northern Oregon and western Idaho: U.S. Geological Survey Tgn1 Tgv Latah Formation Tgr1 Open-File Report 81-797, 32 p., sheet 3 of 5. Imnaha Basalt Swanson, D.A., T.L. Wright, P.R. Hooper, and R.D. Bentley, 1979, Revisions in 5 Tli Sediments interbedded with basalt flows (Miocene)–Mostly coarse sand to stratigraphic nomenclature of the Columbia River Basalt Group: U.S. Qas silt, locally with pebble layers or lenses. Locally includes a hyaloclastic Tim Imnaha Basalt (Miocene)–Medium- to coarse-grained, sparsely to abundantly Geological Survey Bulletin 1457-G, 59 p. Qas deposit and sediment at the top of the Imnaha Basalt that is as much as 200 plagioclase-phyric basalt; olivine common; plagioclase phenocrysts generally Vallier, T.L., 1974, The Permian and Triassic Seven Devils Group, western Idaho Qas feet thick. The hyaloclastic unit is probably more extensive than mapped, 0.5-2 cm long but some are as large as 3 cm. Normal magnetic polarity. Qas and northeastern Oregon: U.S. Geological Survey Bulletin 1437, 58 p. Tim but it is generally poorly exposed or covered with colluvium. Several other About 600 feet of Imnaha basalt is exposed in the Salmon River canyon. thin, discontinuous interbeds, some too thin to show at the map scale, occur Locally, hyaloclastic deposits and sediments at the top of the unit (included Qag Qt Qafo in the Imnaha Basalt and below the basalt of Grangeville flow. in Tli unit) are as much as 200 feet thick. This hyaloclastic unit is likely more Qaf extensive than mapped, but typically is easily weathered and covered with Qaf Tli 06JK036 Mass Movement Deposits colluvial debris. Crude columnar structure within part of the deposits indicates the material was likely hot at the time of deposition. Talus (Holocene and Pleistocene)–Angular pebble-, cobble-, and boulder-sized Qam Qt Qls Qam 2 Qas fragments fallen and rolled from bedrock outcrops and accumulated below. Tgr1 INTRUSIVE ROCKS Deposits are characterized by a steeply sloping surface that is at or near the angle of repose. Commonly stabilized by vegetation. KJap Aplite dikes (Jurassic to Cretaceous)–Several fine-grained granitic dikes intrude TRPsd Tli the Seven Devils Group metavolcanic rocks exposed in the Salmon River 60 Qls Landslide deposits (Holocene and Pleistocene)–Poorly sorted and poorly stratified canyon. Probably more abundant than shown. Qt angular basalt cobbles and boulders mixed with silt and clay. Deposited by Qag 60 Qas slumps, slides, and debris flows. In addition to the landslide deposit, the ISLAND-ARC METASEDIMENTARY AND Qaf Qamo unit may include the landslide scarp and the headwall (steep area adjacent Qamo KJap Tim to and below the landslide scarp) from which material broke away (see METAVOLCANIC ROCKS Tgr2 Qam Symbols). Location of landslide deposits in steep canyons is typically Seven Devils Group controlled by the presence of sedimentary interbeds and the interface between 44 06JK022 basalt units and underlying basement rocks. Landslides range in age from Psd Seven Devils Group, undivided (Permian to Triassic)–Greenschist Tgr 15 1 55 ancient, relatively stable features, to those that have been active within the metamorphosed, dominantly green volcaniclastic, volcanic, and sedimentary 55 25 past few years. rocks. Recognizable protoliths include plagioclase-hornblende porphyritic TRPsd 20 20 volcanic flow and intrusive (mostly sills) rocks, volcanic breccias, and VOLCANIC ROCKS epiclastic conglomerate, graywacke, siltstone, and argillite. Epiclastic rocks 20 15 contain common feldspar crystals in addition to volcanic lithic fragments. 18 35 Columbia River Basalt Group Probably correlative to the Wild Sheep Creek Formation of Vallier (1974). 54 Qls 15 The stratigraphic nomenclature for the Columbia River Basalt Group follows 37 Tgn1 TRPsd that of Swanson and others (1979) and Camp (1981). In Idaho, the group Tgn KJap 1 is divided into four formations. From oldest to youngest, these are Imnaha KJap 35 Basalt, Grande Ronde Basalt, Wanapum Basalt, and Saddle Mountains Basalt. Imnaha Basalt is exposed in the Salmon River and Rock Creek canyons in Tgr1 30 the southwest part of the quadrangle. Grande Ronde Basalt, from oldest to 33 Qas youngest, has been subdivided into the informal R1, N1, R2, and N2 50 TRPsd B Base map scanned from USGS film-positive base, 1963. SCALE 1:24,000 Field work conducted 2002 and 2006. MN Topography by photogrammetric methods from aerial photographs taken 1 0.5 0 1 This geologic map was funded in part by the U.S. Geological Survey 1961. Field checked 1963. MILE National Cooperative Geologic Mapping Program, GN FEET o o USGS Award No. 06HQAG0020. Transverse Mercator. 1927 North American Datum. 0 30 20 1000 0 1000 2000 3000 4000 5000 6000 7000 10,000-foot grid ticks based on Idaho coordinate system, west zone. Digital cartography by Jesse S. Bird and Jane S. Freed at the KILOMETER Idaho Geological Survey’s Digital Mapping Lab. 1000-meter Universal Transverse Mercator grid ticks, zone 11. 1 0.5 0 1 IDAHO Table 1. Major oxide and trace element chemistry of basalt samples collected in the Fenn quadrangle. Note on printing: The map is reproduced at a high resolution of 600 dots National geodetic vertical datum of 1929. UTM Grid and 1963 Magnetic North Contour interval 40 feet. per inch. The inks are resistant to run and fading but will deteriorate with QUADRANGLE long-term exposure to light. Major elements in weight percent Trace elements in parts per million Declination at Center of Map Dotted lines represent 20-foot contours. LOCATION PDF map (Acrobat Reader) may be viewed at www.idahogeology.org. Sample Map number Latitude Longitude Unit name unit SiO TiO Al O FeO* MnOMgO CaO Na O K OPO Ni Cr Sc V Ba Rb Sr Zr Y Nb Ga Cu Zn Pb La Ce Th Nd Map version 6-7-2007. 2 2 2 3 2 2 2 5 **VC79-410 45.9968 -116.32311 Grande Ronde Basalt R Tgr ? 55.12 2.37 14.98 11.77 0.19 3.49 6.89 2.85 1.75 0.38 Grave Creek 2 2

Fault 02DG012 45.94662 -116.36235 Grande Ronde Basalt R1 Tgr1 53.45 2.442 14.05 11.39 0.195 4.99 8.83 2.97 1.34 0.344 20 71 25 371 466 36 338 178 34 14.2 21 47 121 5 11 45 3 A A’ 02DG013 45.95006 -116.36312 Grande Ronde Basalt R1 Tgr1 54.00 2.519 13.70 12.16 0.207 4.31 7.93 3.14 1.67 0.375 6 27 34 366 537 40 341 202 38 14.8 21 34 124 5 22 52 6 4000 Grave Creek 4000 Tgv Tgv 02DG014 45.95597 -116.36301 Grande Ronde Basalt R Tgr 53.83 2.446 13.88 11.97 0.207 4.48 8.10 3.18 1.54 0.364 11 33 38 358 516 35 345 196 37 13.9 23 36 125 6 36 53 2 Tgr2 Tgr2 Tgr2 1 1 Qas Tgv Tgv 02DG015 45.95929 -116.36195 Grande Ronde Basalt R Tgr 53.38 2.192 14.42 11.63 0.189 4.89 8.71 3.11 1.17 0.317 30 63 38 290 500 24 346 179 35 14.5 22 85 118 7 14 44 5 Qas 1 1 Tgn 3000 1 3000 02DG016 45.96388 -116.35981 Grande Ronde Basalt R1 Tgr1 54.29 2.184 14.08 11.19 0.197 4.75 8.37 3.13 1.46 0.341 21 51 32 344 513 36 326 180 36 13.8 22 78 122 7 20 46 6 Tgn1 FEET Tgn1 02DG017 45.96693 -116.3608 Grande Ronde Basalt R1 Tgr1 54.54 2.269 13.92 11.53 0.200 4.44 8.03 3.19 1.52 0.349 17 48 32 332 533 40 324 191 38 13.6 21 71 118 6 33 68 5 FEET Tgr1 Tgr1 Tgr1 02DG018 45.97731 -116.35724 Grande Ronde Basalt N1 Tgn1 57.31 2.260 13.57 11.02 0.196 3.16 6.75 3.38 2.02 0.327 6 21 36 356 732 51 310 199 40 13.5 22 21 124 12 24 43 5 2000 Tim 2000 02DG019 45.98054 -116.35664 Grande Ronde Basalt N Tgn 56.49 2.236 13.38 12.07 0.217 3.19 6.74 3.26 2.09 0.325 4 24 39 352 690 53 309 198 38 14.4 23 21 123 7 29 49 7 Tim Tim 1 1

02DG020 45.98751 -116.35527 Grande Ronde Basalt N1 Tgn1 55.06 2.118 13.73 12.09 0.210 3.98 7.65 3.29 1.49 0.388 12 27 40 379 641 36 311 179 39 13.4 22 47 125 5 20 47 5 1000 1000 02DG021 45.99565 -116.36319 Grande Ronde Basalt N Tgn1 55.45 1.975 14.07 10.95 0.205 4.24 7.95 3.18 1.62 0.364 12 31 36 362 602 36 323 165 39 12.2 22 43 121 7 14 46 6 TRPsd? 1 TRPsd? TRPsd? 02DG022 45.9985 -116.37101 Grande Ronde Basalt N1 Tgn1 54.91 2.201 13.71 12.28 0.212 3.74 7.63 3.27 1.61 0.424 13 22 26 392 656 35 317 188 43 13.5 21 51 129 4 12 54 1 0 0 02DG023 45.9986 -116.37103 Grande Ronde Basalt N1 Tgn1 55.96 1.801 14.34 10.44 0.189 4.31 8.01 3.32 1.38 0.245 4 15 33 309 539 36 317 155 33 11.3 20 19 112 6 22 26 5

02DG024 45.99865 -116.37058 Grande Ronde Basalt N1 Tgn1 57.20 1.851 14.65 8.78 0.171 4.35 8.03 3.11 1.60 0.256 4 18 38 313 709 38 334 158 37 11.4 18 17 114 7 13 44 4 02DG042 45.97463 -116.28213 basalt of Grangeville Tgv 53.31 1.377 15.52 9.15 0.202 6.01 10.95 2.66 0.65 0.170 33 135 31 238 521 11 255 130 24 14.5 19 59 78 2 23 48 4 Rock B’ 02DG043 45.99146 -116.3093 Grande Ronde Basalt R Tgr2 55.79 2.417 13.79 12.27 0.182 3.24 6.91 3.17 1.77 0.453 10 18 32 352 973 46 339 192 38 15.6 24 23 128 8 22 45 5 Tgr2 Creek 4000 2 Tgv Tgr 2 Tgv Tgv Tgv 02DG044 45.98159 -116.2924 basalt of Grangeville Tgv 53.26 1.308 15.81 8.09 0.145 6.56 11.47 2.56 0.62 0.163 32 167 31 226 402 13 253 123 29 14.2 19 36 69 527133 Qls B 06JK004 45.96457 -116.35579 Grande Ronde Basalt, breccia dike Tgbd 55.45 2.108 13.78 11.88 0.210 3.83 7.63 3.17 1.57 0.369 12 9 35 370 635 38 316 180 37 11.3 22 42 123 10 22 47 3 28 3000 Salmon Tgn Qas 3000 1 06JK022 45.88888 -116.26639 Grande Ronde Basalt R Tgr 56.30 2.220 13.88 11.41 0.195 3.36 6.97 3.31 1.93 0.426 8 14 32 322 725 51 346 184 33 11.6 22 12 128 11 27 61 5 32 River Tgn 2 2 Tim 1 06JK023 45.94239 -116.27741 Grande Ronde Basalt N Tgn 55.75 2.378 13.68 12.02 0.209 3.33 6.99 3.29 1.89 0.446 12 5 31 360 753 48 322 191 36 13.0 22 20 131 10 24 59 5 30 Tgr1 1 1 2000 Tgr 2000 1 06JK036 45.89839 -116.31019 Grande Ronde Basalt R2 Tgr2 55.64 2.368 13.50 12.65 0.199 3.27 6.75 3.37 1.81 0.443 13 6 31 361 764 49 317 190 37 13.2 22 24 133 10 30 62 5 32 Tim FEET 06JK050 45.95642 -116.34769 Grande Ronde Basalt R Tgr 55.58 2.373 13.56 12.45 0.215 3.30 6.93 3.39 1.75 0.453 13 5 32 361 820 43 323 189 36 12.1 22 23 133 10 31 63 5 31 Tim? 2 2 FEET TRPsd 06JK058 45.94675 -116.32253 Grande Ronde Basalt, breccia dike Tgb 56.17 1.784 14.26 10.53 0.197 4.30 7.98 3.01 1.51 0.247 9 7 33 315 578 38 319 154 30 9.6 21 15 115 9 17 38 3 25 1000 1000 d

TRPsd? 06JK062 45.94125 -116.32014 Grande Ronde Basalt, breccia dike Tgbd 55.64 2.098 13.83 11.90 0.199 3.77 7.65 3.10 1.44 0.375 14 9 33 364 743 36 325 178 36 10.8 21 40 124 9 24 49 3 28 TRPsd? * Major elements are normalized on a volatile-free basis, with total Fe expressed as FeO. 0 0 ** Samples collected by V. Camp in 1979. Analytical results used with permission (Camp, written commun., 2002). All analyses performed at Washington State University GeoAnalytical Laboratory, Pullman, Washington.

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