DOCSLIB.ORG

GEOLOGIC MAP of the LEONIA QUADRANGLE, BONNER and BOUNDARY COUNTIES, IDAHO, and Laterally and Nonuniform in Thickness

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
GEOLOGIC MAP of the LEONIA QUADRANGLE, BONNER and BOUNDARY COUNTIES, IDAHO, and Laterally and Nonuniform in Thickness IDAHO GEOLOGICAL SURVEY IDAHOGEOLOGY.ORG DIGITAL WEB MAP 149 MONTANA BUREAU OF MINES AND GEOLOGY MBMG.MTECH.EDU MBMG OPEN FILE 626 CORRELATION OF MAP UNITS rock less than 10 km (6 mi) to the west has too much quartz to be entirely igneous (Redfield, 1986). Locally stratiform, but generally discontinuous GEOLOGIC MAP OF THE LEONIA QUADRANGLE, BONNER AND BOUNDARY COUNTIES, IDAHO, AND laterally and nonuniform in thickness. Commonly floored by mafic sills. Alluvial and Colluvium and Glacial and Related Deposits Locally contains 5-10 percent clasts of laminated siltite and argillite a few Lacustrine Deposits Mass Wasting Deposits centimeters thick, some of which have apparent reaction rims; others Qal Qlm Qt Qglc Holocene appear deformed. Weathers more rusty than quartzite of Ype or Ypc. Gener- LINCOLN COUNTY, MONTANA ally hardest rock of the Prichard Formation, forming rounded exposures, Quaternary Qgl Qgo Qg Qgt Pleistocene abundant rounded float, and large blocky talus. May have formed from increased pore fluid pressure due to heating by the earlier sills (Anderson and Höy, 2000). Poorly exposed near southwest corner of map. Russell F. Burmester1, Mark D. McFaddan1, Roy M. Breckenridge1, Reed S. Lewis1, and Jeffrey D. Lonn2 Intrusive Rocks Belt-Purcell Kbgd Cretaceous Supergroup STRUCTURE 2012 Yms 3-4 The major structure in this quadrangle is the Moyie fault. It is characterized Yms1-2 regionally as an east-vergent thrust and juxtaposes older rocks on the west Ysh2 (hanging wall) against younger rocks on the east, consistent with this 60 13 Ypf 55 Qal Ysh interpretation. However, strata of the hanging and foot walls face each Ymi Ymic Ymi Yms 1 48 1-2 Qgl other, giving the impression that the fault occupies a syncline. Support for a Ysn Ypab 45 Mesoproterozoic synclinal fold geometry comes from existence of a slightly east-verging, Ymi Qgl Yms3-4 75 Yw 60 Qg southward-plunging syncline west of the Moyie fault in this quadrangle, Ype Qg 75 Qgt 55 Ypf and an open, northward-plunging syncline north of the international border 50 Ype 58 Ypd Ypf Ymic (Brown and others, 1995; Brown, 1998). One hypothesis is that these are Ype Ype 60 Ysh remnants of a syncline that was paired with the Sylvanite anticline to the Ypc 48 2 Ypd 80 Ysn Ymi east (Fig. 1) before further contraction was accommodated by faulting. This 50 Qglc 70 Ypc situation is consistent with the interpretation that the Moyie fault cut down 55 55 60 Ysh1 85 section into the Sylvanite anticline (Harrison and Cressman, 1993), so must Qglc Ypab Ypm 60 45 Qgl be younger. However, in the Curley Creek quadrangle to the north, the 55 Qgl 65 73 Moyie fault is overturned and Yms1-2 stromatolites dip steeply east, not the 56 attitude expected of a thrust fault. This configuration could be explained if Ymi Ymic 55 80 Ypab Ype veinlets. Dolomite is blue-gray where fresh and weathers light brown to orange. the fault and adjacent beds were folded as part of the west limb of the Ymic Qg 20 Thickness calculated from outcrop width in southern part of quadrangle is 420 Sylvanite anticline as it continued or renewed growth after or during thrust m (1,300 ft), but upper contact is faulted. Best exposed along east side of Koote- 50 SYMBOLS faulting. This syncline-thrust system is complicated by an east-side-up fault 50 A' nai River at north edge of map. Corresponds closely to members 3 through 5 of west of the Moyie fault that repeats part of the Prichard section, and numer- 25 Qgl 41 80 Contact: dashed where approximately located. Harrison and others (1992). Qgt 60 Qgl ous faults to the east. Some of those mapped as east-vergent thrusts may 60 25 25 Ypd date from late stages of folding or be coeval with the Moyie fault. Ysn Yms1-2 Mount Shields Formation, members 1 and 2 (Mesoproterozoic)—Red, 50 51 Thrust fault: teeth on upper plate; ball dashed where approximately Ypab Ypc Ype 45 75 pink, green, and gray quartzite, green and red siltite and argillite, and minor 55 Ysh2 located; dotted where concealed. Ypm Qgl carbonate. Green and lighter colors are more common toward base. Quartzite 60 50 55 58 Ymi 75 Yw 75 65 Qal 80 is in 0.3 m to rarely 1.0 m beds. It is fine grained and mostly flat laminated, but 55 Qgl Yms 50 Ymi Ypf 1-2 Normal fault: ball and bar on downthrown side; dashed where also cross laminated. Potassium feldspar is well in excess of plagioclase. Qgt 50 REFERENCES Qglc 58 Ymic 48 approximately located; dotted where concealed. Diffuse, nonresistant brown wisps of carbonate within the quartzite of upper Yms1-2 Ymi Ysh1 part of unit average a few centimeters in thickness and 10-15 cm in length. Ype Ypc 55 Ype Ypf Qal 65 Anticline axial trace; dashed where approximately located; dotted where Commonly rippled tops of the quartzite beds have thin red argillite drapes. Anderson, H.E., and D.W. Davis, 1995, U-Pb geochronology of the Moyie sills, Purcell Ypd 75 62 60 Ysn concealed. Siltite and argillite occur as graded and lenticular couplets and microlaminae. Supergroup, southeastern British Columbia: Implications for the Mesoproterozoic Ypab Qgl Ypm Ymi 60 65 Both red and green couplets have dewatering structures, mudcracks, and geological history of the Purcell (Belt) basin: Canadian Journal of Earth Sciences, Ymi 50 Yms3-4 Qgl Qal 70 Ypc 85 Syncline axial trace; dashed where approximately located; dotted where v. 32, no. 8, p. 1180-1193. 70 Ypc 75 mudchip breccias. Green strata may have more disrupted zones, but red strata Ymi 75 Qgl concealed. 35 52 Qgl have larger mudchips. Uppermost 35 m (115 ft) contains several 1-5 dm, rarely Anderson, H.E., and W.D. Goodfellow, 2000, Geochemistry and isotope chemistry of the 35 Ymi Qal Ysn 10 dm, layers of purple, buff-weathering low domal stromatolites as much as 30 Moyie sills: Implications for the early tectonic setting of the Mesoproterozoic Purcell 55 10 Strike and dip of bedding. Qgt Ypab cm high and 1 meter across, with bases of oolite and coarse, well-rounded basin, in J.W. Lydon, Trygve Höy, J.F. Slack, and M.E. Knapp, eds., The Geological 55 55 Ysh 55 1 quartz grains. Top placed above highest domal stromatolite. Best exposed near Environment of the Sullivan Deposit, British Columbia: Geological Association of Ypf Ysh Qal 20 Strike and dip of bedding; ball indicates bedding known to be upright. Ymi Qg 80 2 70 south edge of section 20 along Kootenai River. Thickness calculated from Canada, Mineral Deposits Division, Special Publication No. 1, p. 302-321. 13 Ymi 30 Ymi Anderson, H.E., and Trygve Höy, 2000, Fragmental sedimentary rocks of the Aldridge Ypc 17 10 Estimated strike and dip of bedding. outcrop width there about 300 m (1,000 ft). Corresponds closely to members 1 65 Formation, Purcell Supergroup, British Columbia, Chapter 14, in J.W. Lydon, 52 60 Qg and 2 of Harrison and others (1992). 50 45 Trygve Höy, J.F. Slack, and M.E. Knapp, eds., The Geological Environment of the Qgl 75 Ymi 50 Strike and dip of bedding, strike variable. MOYI 70 20 Sullivan Deposit, British Columbia: Geological Association of Canada, Mineral 54 Shepard Formation (Mesoproterozoic)—Occupies same stratigraphic level as Ypc Qgl 65 Ysn Deposits Division, Special Publication No. 1, p. 259-271. 55 the upper two units of the Wallace Formation mapped to the south of the 55 E Strike of vertical bedding. Ypab 40 50 Ypf Qgl Bishop, D.T., 1973, Petrology and geochemistry of the Purcell sills in Boundary 10 45 60 quadrangle (Harrison and Jobin, 1963; Lewis and others, 1999, 2000, Ymi Qglc County, Idaho, in Belt Symposium, Volume 2: Idaho Bureau of Mines and Geology 8 40 65 2002). Named Shepard Formation here because it is not markedly different 45 55 Horizontal bedding. Special Publication, p. 16-66. 5 60 70 17 30 from the Shepard Formation at its type locality and is separated from the 10 Qg Ymi 46 FAULT 70 Bishop, D.T., 1976, The petrology and geochemistry of the Purcell sills, Boundary Ypab 55 Qal Strike and dip of overturned bedding. carbonate-bearing pinch-and-swell strata typical of the Wallace Formation County, Idaho, and adjacent areas: University of Idaho Ph.D. dissertation, 147 p. 81 Ypc Ymi 70 8 Qglc Ypc 61 Ysn as found near Wallace, Idaho, by carbonate-free laminated strata (Ysn). Breckenridge, R.M., and W.M. Phillips, 2010, New cosmogenic 10Be surface exposure 10 Qg 65 45 Strike and dip of foliation. Subdivision follows Lemoine and Winston (1986) and Burmester (1986). 5 30 50 70 ages for the Purcell Trench lobe of the Cordilleran Ice Sheet in Idaho: Geological 5 40 40 20 27 Qg Society of America Abstracts with Programs, v. 42, no. 5, p. 309. 35 Strike and dip of cleavage. Ysh2 Shepard Formation, member 2 (Mesoproterozoic)—Microlaminated to 41 Ymi Brown, D.A., 1998, Geological compilation of the Yahk (east half) and Yahk River (west 28 Ypc 20 laminated dark gray to black argillite, dark olive-green- to white-weathering half) map areas, southeastern British Columbia: British Columbia Ministry of Ymi Qg Bearing and plunge of small fold axis. siltite, and very fine-grained white quartzite. Laminations are commonly Ymi Energy and Mines, Minerals Division, Geological Survey Branch, Geoscience Map Ymi Yms3-4 Qlm contorted, rarely cracked. Contortions are attributed to soft-sediment deforma- 1998-2, scale 1:50,000. Ypc 25 Bearing and plunge of asymmetrical small fold showing counterclockwise tion.
Load more

Recommended publications
  • The Cordilleran Ice Sheet 3 4 Derek B
    1 2 The cordilleran ice sheet 3 4 Derek B. Booth1, Kathy Goetz Troost1, John J. Clague2 and Richard B. Waitt3 5 6 1 Departments of Civil & Environmental Engineering and Earth & Space Sciences, University of Washington, 7 Box 352700, Seattle, WA 98195, USA (206)543-7923 Fax (206)685-3836. 8 2 Department of Earth Sciences, Simon Fraser University, Burnaby, British Columbia, Canada 9 3 U.S. Geological Survey, Cascade Volcano Observatory, Vancouver, WA, USA 10 11 12 Introduction techniques yield crude but consistent chronologies of local 13 and regional sequences of alternating glacial and nonglacial 14 The Cordilleran ice sheet, the smaller of two great continental deposits. These dates secure correlations of many widely 15 ice sheets that covered North America during Quaternary scattered exposures of lithologically similar deposits and 16 glacial periods, extended from the mountains of coastal south show clear differences among others. 17 and southeast Alaska, along the Coast Mountains of British Besides improvements in geochronology and paleoenvi- 18 Columbia, and into northern Washington and northwestern ronmental reconstruction (i.e. glacial geology), glaciology 19 Montana (Fig. 1). To the west its extent would have been provides quantitative tools for reconstructing and analyzing 20 limited by declining topography and the Pacific Ocean; to the any ice sheet with geologic data to constrain its physical form 21 east, it likely coalesced at times with the western margin of and history. Parts of the Cordilleran ice sheet, especially 22 the Laurentide ice sheet to form a continuous ice sheet over its southwestern margin during the last glaciation, are well 23 4,000 km wide.
    [Show full text]
  • Seismotectonic Interpretation of the 2015 Sandpoint, Idaho, Earthquake Sequence
    Seismotectonic Interpretation of the 2015 Sandpoint, Idaho, Earthquake Sequence Daisuke Kobayashi Kenneth F. Sprenke Michael C. Stickney William M. Phillips Idaho Geological Survey University of Idaho 875 Perimeter Drive MS 3014 Staff Report 16-1 Moscow, Idaho 83844-3014 August 2016 www.IdahoGeology.org Seismotectonic Interpretation of the 2015 Sandpoint, Idaho, Earthquake Sequence Daisuke Kobayashi1 Kenneth F. Sprenke1 Michael C. Stickney2 William M. Phillips3 Staff Reports present timely information for public distribution. This publication may not conform to the Agency’s standards. Idaho Geological Survey University of Idaho 875 Perimeter Drive MS 3014 Staff Report 16-1 Moscow, Idaho 83844-3014 August 2016 www.IdahoGeology.org 1Department of Geological Sciences, University of Idaho, Moscow, Idaho 83844-3022 2Montana Bureau of Mines and Geology, Butte, Montana 59701-8997 3Idaho Geological Survey, University of Idaho, Moscow, Idaho 83844-3014 Contents ABSTRACT .........................................................................................................................1 INTRODUCTION ...............................................................................................................1 REGIONAL TECTONIC SETTING AND SEISMICITY .................................................2 THE 24 APRIL 2015 SANDPOINT EARTHQUAKE SEQUENCE .................................9 FAULT PLANE SOLUTIONS..........................................................................................13 TECTONIC IMPLICATIONS...........................................................................................17
    [Show full text]
  • Characterization of Ecoregions of Idaho
    1 0 . C o l u m b i a P l a t e a u 1 3 . C e n t r a l B a s i n a n d R a n g e Ecoregion 10 is an arid grassland and sagebrush steppe that is surrounded by moister, predominantly forested, mountainous ecoregions. It is Ecoregion 13 is internally-drained and composed of north-trending, fault-block ranges and intervening, drier basins. It is vast and includes parts underlain by thick basalt. In the east, where precipitation is greater, deep loess soils have been extensively cultivated for wheat. of Nevada, Utah, California, and Idaho. In Idaho, sagebrush grassland, saltbush–greasewood, mountain brush, and woodland occur; forests are absent unlike in the cooler, wetter, more rugged Ecoregion 19. Grazing is widespread. Cropland is less common than in Ecoregions 12 and 80. Ecoregions of Idaho The unforested hills and plateaus of the Dissected Loess Uplands ecoregion are cut by the canyons of Ecoregion 10l and are disjunct. 10f Pure grasslands dominate lower elevations. Mountain brush grows on higher, moister sites. Grazing and farming have eliminated The arid Shadscale-Dominated Saline Basins ecoregion is nearly flat, internally-drained, and has light-colored alkaline soils that are Ecoregions denote areas of general similarity in ecosystems and in the type, quality, and America into 15 ecological regions. Level II divides the continent into 52 regions Literature Cited: much of the original plant cover. Nevertheless, Ecoregion 10f is not as suited to farming as Ecoregions 10h and 10j because it has thinner soils.
    [Show full text]
  • Geologic Map of the Line Point Quadrangle, Boundary County Idaho, and Lincoln County, Montana
    IDAHO GEOLOGICAL SURVEY IDAHOGEOLOGY.ORG IGS DIGITAL WEB MAP 150 MONTANA BUREAU OF MINES AND GEOLOGY MBMG.MTECH.EDU MBMG OPEN FILE 623 white graded or nongraded argillite tops. Conspicuous bar code-like REFERENCES patterns in the middle, formed by alternating dark and light siltite, persist regionally (Huebschman, 1973) and have been used as markers for correla- GEOLOGIC MAP OF THE LINE POINT QUADRANGLE, BOUNDARY COUNTY, IDAHO, AND tion by Cominco (Hamilton and others, 2000). Siltite and argillite couplets, Anderson, H.E., and D.W. Davis, 1995, U-Pb geochronology of the Moyie sills, with dark, less commonly light tops, have even and parallel, uneven, wavy Purcell Supergroup, southeastern British Columbia: Implications for the or undulating lamination. Rusty nature of outcrop is due to weathering of Mesoproterozoic geological history of the Purcell (Belt) basin: Canadian CORRELATION OF MAP UNITS abundant sulfides, commonly pyrrhotite. Dominant lamination style and Journal of Earth Sciences, v. 32, no. 8, p. 1180-1193. LINCOLN COUNTY, MONTANA concentration of sulfides vary between members. Quartzite in 2-20 dm beds Anderson, H.E., and W.D. Goodfellow, 2000, Geochemistry and isotope chem- Alluvial and Colluvium and Glacial and Related Deposits is light weathering, averages about 60 percent quartz, 20 percent plagio- istry of the Moyie sills: Implications for the early tectonic setting of the Lacustrine Deposits Mass Wasting Deposits clase, with the rest mostly white micas and 5 percent biotite (Cressman, Mesoproterozoic Purcell basin, in J.W. Lydon, Trygve Höy, J.F. Slack, and 1989). Previous mapping in this area and to the east by Cressman and Harri- M.E.
    [Show full text]
  • Geologic Map of the Curley Creek Quadrangle, Boundary County
    IDAHO GEOLOGICAL SURVEY IDAHOGEOLOGY.ORG DIGITAL WEB MAP 148 MONTANA BUREAU OF MINES AND GEOLOGY MBMG.MTECH.EDU MBMG OPEN FILE 625 CORRELATION OF MAP UNITS Ravalli Group STRUCTURE GEOLOGIC MAP OF THE CURLEY CREEK QUADRANGLE, BOUNDARY COUNTY, IDAHO, AND The Ravalli Group that crosses the northeast quadrant of the map is only Alluvial and Colluvium and Glacial and Related Deposits slightly thicker than documented to the southeast (Cressman and Harrison, The major structure in this quadrangle is the Moyie fault. It is characterized Lacustrine Deposits Mass Wasting Deposits 1986) and south-southwest (Burmester and others, 2007). Although cosets regionally as an east-vergent thrust and juxtaposes older rocks on the west QalQQar lm Qt Qcg Qglc Holocene of thick sets of quartzite used to define the Revett elsewhere (Hayes, 1983; (hanging wall) against younger rocks on the east, consistent with this LINCOLN COUNTY, MONTANA Hayes and Einaudi, 1986) are rarely observed, Revett is mapped on the east interpretation. However, strata of the hanging and foot walls face each Quaternary side of the Sylvanite anticline, Fig. 1, (Cressman and Harrison, 1986) and Qgl Qgo Qg Qgt Qgk Pleistocene other, giving the impression that the fault occupies a syncline. Support for a correlated with the middle Creston north of the border where copper-silver- synclinal fold geometry comes from existence of a slightly east-verging, cobalt mineralization is similar to that in the Revett to the south (Hartlaub, southward-plunging syncline west of the Moyie fault south of the map, 1 1 1 1 2 Intrusive Rocks 2009). Revett mapped here as the swath of quartzite-rich strata below more Fig.1, (Miller and Burmester, 2004) and an open, northward-plunging Roy M.
    [Show full text]
  • Quaternary and Late Tertiary of Montana: Climate, Glaciation, Stratigraphy, and Vertebrate Fossils
    QUATERNARY AND LATE TERTIARY OF MONTANA: CLIMATE, GLACIATION, STRATIGRAPHY, AND VERTEBRATE FOSSILS Larry N. Smith,1 Christopher L. Hill,2 and Jon Reiten3 1Department of Geological Engineering, Montana Tech, Butte, Montana 2Department of Geosciences and Department of Anthropology, Boise State University, Idaho 3Montana Bureau of Mines and Geology, Billings, Montana 1. INTRODUCTION by incision on timescales of <10 ka to ~2 Ma. Much of the response can be associated with Quaternary cli- The landscape of Montana displays the Quaternary mate changes, whereas tectonic tilting and uplift may record of multiple glaciations in the mountainous areas, be locally signifi cant. incursion of two continental ice sheets from the north and northeast, and stream incision in both the glaciated The landscape of Montana is a result of mountain and unglaciated terrain. Both mountain and continental and continental glaciation, fl uvial incision and sta- glaciers covered about one-third of the State during the bility, and hillslope retreat. The Quaternary geologic last glaciation, between about 21 ka* and 14 ka. Ages of history, deposits, and landforms of Montana were glacial advances into the State during the last glaciation dominated by glaciation in the mountains of western are sparse, but suggest that the continental glacier in and central Montana and across the northern part of the eastern part of the State may have advanced earlier the central and eastern Plains (fi gs. 1, 2). Fundamental and retreated later than in western Montana.* The pre- to the landscape were the valley glaciers and ice caps last glacial Quaternary stratigraphy of the intermontane in the western mountains and Yellowstone, and the valleys is less well known.
    [Show full text]
  • Geologic Map of the Ritz Quadrangle, Boundary County, Idaho
    IDAHO GEOLOGICAL SURVEY DIGITAL WEB MAP 119 MOSCOW-BOISE-POCATELLO WWW.IDAHOGEOLOGY.ORG BRECKENRIDGE, BURMESTER, AND LEWIS CORRELATION OF MAP UNITS GEOLOGIC MAP OF THE RITZ QUADRANGLE, BOUNDARY COUNTY, IDAHO Made Alluvial and Colluvium and Deposits Lacustrine Deposits Mass Wasting Deposits Glacial and Related Deposits Disclaimer: This Digital Web Map is an informal report and may be m revised and formally published at a later time. Its content and format Qal Qaf Qlm Qc Qglc Holocene may not conform to agency standards. Quaternary Roy M. Breckenridge, Russell F. Burmester, and Reed S. Lewis Qgl Qgo Qgt Qgk Qgls Pleistocene 2010 Intrusive Rocks Kgbf Kgc Kgc Cretaceous 75 Qgl Qgt Qglc Metasedimentary Kgc Rocks Kgc Kgc Ymi Qglc Qgl Qgt Ypm Ypab Mesoproterozoic Qglc Kgc 75 Qgk INTRODUCTION Kgc Granodiorite of Copeland (Cretaceous)—Porphyritic, medium- to coarse- Qgt grained hornblende-biotite and biotite granodiorite that underlies eastern Qlm half of quadrangle. Microcline phenocrysts are as long as 4 cm. Plagioclase Quaternary deposits on the Ritz 1:24,000-scale quadrangle were mapped has strong oscillatory zonation and average composition of an28. Quartz Qlm in 1997-8 and 2009 by R.M. Breckenridge. Bedrock was mapped in 2009 typically in aggregates 4-8 mm across. Myrmekitic intergrowth of quartz by R.F. Burmester and R.S. Lewis to augment mapping by R.F. Burmester and feldspar common. Color index 13-17; biotite is more than twice as Qlm (1982, 1985-86) and F.K. Miller (1994). Plutonic rock descriptions are abundant as hornblende in most of pluton; hornblende sparse or lacking at modified from Miller and Burmester (2004).
    [Show full text]
  • Geophysical Interpretation of the Gneiss Terrane of Northern Washington and Southern British Columbia, and Its Implications for Uranium Exploration
    Geophysical Interpretation of the Gneiss Terrane of Northern Washington and Southern British Columbia, and Its Implications for Uranium Exploration GEOLOGICAL SURVEY PROFESSIONAL PAPER Geophysical Interpretation of the Gneiss Terrane of Northern Washington and Southern British Columbia, and Its Implications for Uranium Exploration By JOHN W. CADY and KENNETH F. FOX, JR. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1260 Gravity highs suggest that gneiss domes of the Omineca crystalline belt are the surface expression of a zone of dense infrastructure UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1984 UNITED STATES DEPARTMENT OF THE INTERIOR WILLIAM P. CLARK, Secretary GEOLOGICAL SURVEY Dallas L. Peck, Director Library of Congress Cataloging in Publication Data Cady, John W. Geophysical interpretation of the gneiss terrane of northern Washington and southern British Columbia and its implications for uranium exploration. (Geological Survey Professional Paper ; 1260) Bibliography: 29 p. 1. Gneiss Washington (State) 2. Gneiss British Columbia. 3. Uranium ores Washington (State) 4. Uranium ores British Columbia. I. Title. II. Series. QE475.G55C3 553.4'932 81-607564 AACR2 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 CONTENTS Page Abstract ............ Gravity studies continued Introduction .......... Regional crustal models .................. 13 Geologic setting ........ East-west gravity model ............... 15 Cenozoic plate-tectonic setting North-south gravity model .............. 17
    [Show full text]
  • Ice Age Floods
    Ice Age Floods Glacial Lake Missoula Remember Manny the Mastodon, Syd the Sloth, and the humongous ice dam that broke, saving their “herd” in the Ice Age movie. Well, almost of southeastern Washington was impacted by several massive real‐life floods caused by the breakups of colossal ice dams in northern Idaho. In the 1920s, a geologist named J Harlen Bretz spent years studying massive landforms in eastern Washington, collectively known as the "Channeled Scablands". Bretz noted that streams in many of the canyons were far too small to have eroded such large gorges. The presence of "dry falls", huge boulders out of place geologically, and out of scale “fossil” ripples in gravel bars led Bretz to conclude that these oversized features were created by some sort of massive flood But where could such a massive flood originate? Would you believe Western Montana? During the last ice age, between 15,000 and 13,000 years ago, the Purcell Trench Lobe of the Cordilleran Ice Sheet formed an ice dam blocking the Clark Fork River at about Sandpoint, Idaho and creating Glacial Lake Missoula. The site of Missoula itself was under 900 feet of water. Over the course of 2,000 years, the ice dam of Glacial Lake Missoula failed repeatedly, rapidly emptying the contents of the lake. After overflowing the shores of Glacial Lake Columbia, the floods spread out across the landscape and tore a myriad of channels across much of eastern Washington, creating the Channeled Scablands. Page | 1 The floodwaters then flowed across the Quincy and Pasco basins before damming up temporarily behind Wallula Gap, a topographic constriction at the border of modern‐day Washington and Oregon.
    [Show full text]
  • T, Copy Is PUBLIC PROPERTY * * to Rmaoyad from the Official File*
    UNITED STATES DEPARTMENT OF THE INTERIOR J. A. Krug, Secretary GEOLOGICAL SURVEY W. E. Wrather, Director Water-Supply Paper 866 GEOLOGY OF DAM SITES ON THE UPPER TRIBUTARIES OF THE COLUMBIA RIVER IN IDAHO AND MONTANA By C. E. ERDMANN »t, coPy is PUBLIC PROPERTY * * to rMaoyad from the official file*. PRIVATE ^ POSSESSION IS UNLAWFUL (R- s- S*** Vol« Z* W* f»c. 749) UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON: 1947 CONTENTS [The letters in parentheses preceding the titles are those nsed to designate the papers for separate publication] Page (A) Part 1, Katka, Tunnel No. 8, and Kootenai Falls dam sites, Kootenai River, Idaho and Montana. __________________________________ 1 (B) Part 2, Hungry Horse dam and reservoir site, South Fork Flathead River, Flathead County, Mont________________________________ 37 (C) Part 3, Miscellaneous dam sites on the Flathead River upstream from Columbia Falls, Flathead County, Mont_____________________ 117 ILLUSTRATIONS PLATE 1. Index map of northwestern Montana and northeastern Idaho showing location of dam sites on Kootenai River__________ 2 2. Geologic map of Katka dam site, N% sec. 31, T. 62 N., R. 3 E., Boundary County, Idaho__-___---_______-----__--_--_-- 18 3. A, View upstream through Katka dam site, Idaho; B, Kootenai River trench upstream from Katka dam site, Idaho_______ 26 4. A, View downstream through Tunnel No. 8 dam site, Montana; B, Kootenai River trench upstream from Tunnel No. 8 dam site, Montana_________________________________________ 27 5. Geologic map and cross sections of Kootenai Falls dam site, sees. 13 and 14, T. 31 N., R. 33 W., Lincoln County, Montana. 34 6. A, Kootenai River valley above Kootenai Falls, Mont.; B, Right abutment of lower dam site at Kootenai Falls, Mont- 34 7.
    [Show full text]
  • 2006 Idaho Earth Science Teachers Summer Field Workshop Geology and Natural Hazards of the Lake Pend Oreille-Clark Fork Area J
    2006 Idaho Earth Science Teachers Summer Field Workshop Geology and Natural Hazards of the Lake Pend Oreille-Clark Fork Area July 9-14, 2006 Detail from Geologic Map of the Hope Quadrangle, Bonner County, Idaho by Russell F. Burmester, Roy M. Breckenridge, Reed S. Lewis, and Mark D. McFaddan (2004) Idaho Geological Survey University of Idaho Moscow, Idaho FIELD TRIP GUIDE START - PAVILION, SAM OWEN CAMPGROUND. Take Peninsula Road to State Highway 200. Turn north (left) on Highway 200. Proceed 3.7 miles to highway overlook on west (left) side of highway. STOP 1 - LAKE PEND OREILLE - HIGHWAY SIGN OVERLOOK Lake Pend Oreille, the largest lake in Idaho, is located about 50 miles south of the British Columbia border in the Purcell Trench. The lake level is 2062 feet above sea level, with the surrounding terrain as high as 6000 feet. The maximum depth of the lake is an impressive 1150 feet, the deepest lake, by far, in the region. The location of the lake is probably related to an old river valley controlled by faults. Lake Pend Oreille was carved repeatedly by a lobe of Pleistocene ice, scoured by ice age floods and filled with glacial outwash and flood deposits. Aerial View, southwest above Clark Fork, Idaho, of Green Monarch Mountain and the location of the ice dam at the eastern margin of Lake Pend Oreille Lake Pend Oreille in northern Idaho is a fascinating geomorphic feature. This lake lies in a basin formed by Cordilleran glaciation immediately below the site of the ice dams that repeatedly formed Pleistocene Lake Missoula.
    [Show full text]
  • Kootenai River Subbasin Summary DRAFT Draft Kootenai River Subbasin Summary
    Draft Kootenai1 River Subbasin Summary2 September 29, 2000 Prepared for the Northwest Power Planning Council Subbasin Team Leader Brian Marotz Montana Fish, Wildlife, & Parks Contributors (in alphabetical order): Dale Becker, Confederated Salish and Kootenai Tribes Jim Hayden, Idaho Department of Fish and Game Greg Hoffman, Montana Fish, Wildlife & Parks Sue Ireland, Kootenai Tribe of Idaho Brian Marotz, Montana Fish, Wildlife & Parks Vaughn Paragamian, Idaho Department of Fish & Game Rox Rogers, US Fish and Wildlife Service Scott Soults, Kootenai Tribe of Idaho Alan Wood, Montana Fish, Wildlife & Parks DRAFT: This document has not yet been reviewed or approved by the Northwest Power Planning Council. 1 Spelled Kootenai in the U.S. and Kootenay in Canada. 2 Time constraints did not allow the for the inclusion of significant information for the Canadian portion of the subbasin. However, this information will be included in future planning efforts. Kootenai River Subbasin Summary DRAFT Draft Kootenai River Subbasin Summary Table of Contents Subbasin Description................................................................................................................. 1 General Description ........................................................................................................... 1 Fish and Wildlife Resources..................................................................................................... 12 Fish and Wildlife Status ...................................................................................................
    [Show full text]