geologic map of the scout mountain quadrangle, …geology.isu.edu/maps/scoutmtn_gm-22-m.pdf ·...
TRANSCRIPT
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Zpc Zpd
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MOSCOW-BOISE-POCATELLOIDAHO GEOLOGICAL SURVEY
PLATTGEOLOGIC MAP 22
limestone; some medium- to thick-bedded mottled limestone in upper part; in
quadrangles, Power County, Idaho: U.S. Geological Survey Bulletin 1399, 115 p.Trimble, D.E., and W.J. Carr, 1976, Geology of the Rockland and Arbon
and Power counties, Idaho: U.S. Geological Survey Bulletin 1400, 88 p.Trimble, D.E., 1976, Geology of the Michaud and Pocatello quadrangles, Bannock
Cambrian rocks in southeastern Idaho: U.S. Geological Survey ProfessionalOriel, S.S., and F.C. Armstrong, 1971, Uppermost Precambrian and lowest
Ludlum, J. C., 1942, Pre-Cambrian formations at Pocatello, Idaho: Journal of Geology,
sandstone. Thickness at least 300 meters with no known base. Mountain, three isolated outcrops of grayish green, poorly sorted, feldspathic weathers light gray to light brown. Includes, on the west side of Scout tan to gray cobble conglomerate with interstitial and interbedded sandstone;
Scout Mountain Member, lower cobble conglomerate part (Late Proterozoic)--Massive,
sparsely exposed to be mapped separately. Thickness approximately 100 Bannock Volcanic Member of Trimble (1976) because this rock type is too Mountain Member. Includes the slightly metamorphosed mafic lava in the to brown. Forms a swale between resistant upper and lower parts of the Scout and sandstone, very poorly sorted; typically tan to greenish gray, weathering
Scout Mountain Member, middle diamictite part (Late Proterozoic)--Cobbles, pebbles,
weathering tan, white and purple; minor beds of grit and conglomerate.Scout Mountain Member, upper quartzite part (Late Proterozoic)--Gray quartzite
Approximately 600 meters thick. beds in the bottom 10 meters. Equivalent to the "varved slate" of Ludlum (1942). and siltstone weathers distinctive silvery gray; a few thin limestone or dolomite
Upper Member (Late Proterozoic)--Medium and dark gray, finely laminated argillite
Pocatello Formation (Late Proterozoic)
Total thickness about 100 meters. gray to brown; interbedded with dark gray limestone beds typically 10 meters thick.Blackrock Canyon Limestone (Late Proterozoic)--Tan sandstone and siltstone weathers
of millimeters are distinctive. Thickness 900 meters. to siltite weathering tan to olive; mud cracks and irregular bedding on a scalePapoose Creek Formation (Late Proterozoic)--Gray to brown, very fine-grained quartzite
purple shale lenses near the top. Approximately 1 kilometer thick. minor grit and conglomerate beds; a few green phyllitic siltstone beds andCaddy Canyon Quartzite (Late Proterozoic)--Tan, vitreous, white-weathering quartzite;
color and lack of any carbonate. Thickness about 300 meters. sandstone beds. Can be distinguished from other fine-grained units by its greenInkom Formation (Late Proterozoic)--Green siltstone and mudstone; a few micaceous
quartzite; minor light-colored quartzite, argillite, and conglomerate beds.Mutual Formation (Late Proterozoic)--Purple and maroon quartzite and pebbly
bedded. Approximately 600 meters. fine-grained quartzite; weathers white, pink, tan, and brown; medium to thickCamelback Mountain Quartzite (Lower Cambrian)--Tan to light brown, medium- to
tan to brown sandstone. A few meters of limestone near the middle. ThicknessGibson Jack Formation (Lower Cambrian)--Dark gray shale; minor green mudstone and
Trimble and Carr (1976). Thickness 300-500 meters. Shale of Oriel and Armstrong (1971); equivalent to the Elkhead Limestone of Oriel and Armstrong (1971); may include the limestone part of the Leadbell lower part some thin-bedded oolitic limestone similar to Bancroft Limestone of
Thickness about 300 meters.
Thickness about 800 meters.
Blacksmith and Bancroft Limestones, undifferentiated (Middle Cambrian)--Gray
mostly nodular to platy limestone in lower part. Thickness 500-600 meters. with thin limestone beds; siltstone and some nodular limestone in upper part;Bloomington Formation (Middle Cambrian)--Green mudstone and shale interbedded
v. 50, p. 85-95.
Paper 394, 52 p.
meters.
Zpc
Zpd
Zpq
Zpu
Zb
Zpa
Zc
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500-600 meters.
C– gj
C– cm
C– b
C– bo
REFERENCES
Thickness 300 meters.
DESCRIPTION OF MAP UNITS
dolomite, and limy siltstone. Thickness 200-300 meters.Nounan Formation (Upper and Middle Cambrian)--Gray interbedded limestone,
most quartzite beds. Upper contact placed at the highest quartzite beds. limestone and dolomite; characterized by chalky-weathering feldspar grains inWorm Creek Quartzite (Upper Cambrian)--Gray to tan quartzite with interbedded
intraformational conglomerate and chert; a few dolomite beds near the top.St. Charles Limestone (Upper Cambrian)--Dark and medium gray limestone with minor
characteristic pink near exposures of carbonate rocks. Exposed thickness about to pale green felsic tuff. Diamictite near exposures of older rock; weathers conglomerate, tuffaceous sandstone, and mudstone interfingering with whiteSalt Lake Formation (Pliocene and Miocene)--Heterogeneous unit including pink to tan
cemented. Thickness exceeds 70 meters.Gravel (Pleistocene and/or Pliocene)--Coarse gravel to sand; consolidated and weakly
Talus (Holocene and Pleistocene)--Large angular blocks at the base of cliffs and steep
alluvium too small to show separately. Thickness generally 2-5 meters. includes colluvium on hillsides and slumped material; includes in a few places rounded rock debris, sand, and mud; unconsolidated and generally unstratified;Unconsolidated debris (Holocene and Pleistocene)--Very coarse to fine, angular to
obscures underlying rocks; small accumulations not shown. Thickness generallyLoess (Holocene and Pleistocene)--Tan and buff unbedded silt, shown only where it
Maximum thickness greater than 5 meters. bottoms and alluvial fans. Grades laterally into and locally includes colluvium.Alluvium (Holocene and Pleistocene)--Tan unconsolidated sand and gravel in valley
Thickness about 250 meters.
Tsl
1 kilometer.
C– n
C– sw
C– sc
hillsides.
5-10 meters.
QTgv
Qt
Qd
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Qal
1998Lucian B. Platt
GEOLOGIC MAP OF THE SCOUT MOUNTAIN QUADRANGLE, BANNOCK COUNTY, IDAHO
CORRELATION OF MAP UNITS
Zpc
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C– cm
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Unconformity
Unconformity
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Tsl
Qd Qt
PROTEROZOICLATE
LOWERCAMBRIAN
UPPERCAMBRIAN
MIDDLECAMBRIAN
PRECAMBRIAN
PALEOZOIC
TERTIARY
Pleistoceneand/or
Pliocene
Pliocene
Mioceneand
Pleistocene
Holoceneand
QUATERNARY
CENOZOIC
University of Idaho, Moscow, Idaho 83844-3014Published and sold by the Idaho Geological Survey
Control by USGS and USC&GS.
Topography by photogrammetric methods from aerialphotographs taken 1967. Field checked 1968.
Polyconic projection. 1927 North American datum100,000-foot grid based on Idaho coordinate system,east zone. 1000-meter Universal TransverseMercator grid ticks, zone 12.
Base map USGS Digital Raster Graphic. Reviewed by Kevin Hefferan, University of Wisconsin-Stevens Point.
Survey’s Digital Mapping and Information Lab.Digital cartography by Jane S. Freed at the Idaho Geological
Field work conducted in 1977-1978, 1986
Thrust fault: dashed where approximately located; teeth on upper plate.
Strike and dip of fracture cleavage.
Strike and dip of beds.
Contact: dashed where approximately located.
Fault: dashed where approximately located; dotted where concealed;bar and ball on downthrown side.
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5
SYMBOLS
NATIONAL GEODETIC VERTICAL DATUM OF 1929
1
1
1/2
SCALE 1:24,000
CONTOUR INTERVAL 40 FEET
0.5 0
0
1 KILOMETER
1 MILE
GN
UTM GRID AND 1968 MAGNETIC NORTHDECLINATION AT CENTER OF SHEET
0 53
17
MN
IDAHO
QUADRANGLE LOCATION