Rock Exposures# in the Study# Area - IIHR · GEOLOGIC# UNIT CONTACT BEDROCK WELL DATA POINT COUNTY#...
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Transcript of Rock Exposures# in the Study# Area - IIHR · GEOLOGIC# UNIT CONTACT BEDROCK WELL DATA POINT COUNTY#...
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GEOLOGIC UNIT CONTACT
BEDROCK WELL DATA POINT
COUNTY BOUNDARY OR TOWN
MAJOR HIGHWAY
Interstate Route
US Route
State Route
TOWNSHIP BOUNDARY
RIVER OR STREAM
Description of Map Symbols
#
Scale 1:250,000
5 0 5 10 15 Miles
5 0 5 10 15 Kilometers
(if printed 36" x 40" format)
DIGITAL GEOLOGIC MAP OF IOWAPHASE 3 : NORTH - CENTRAL IOWA
Prepared by
Brian J. Witzke
Greg A. Ludvigson
Raymond R. AndersonBill J. Bunker
Energy and Geological Resources DivisionGeological Survey Bureau
May 2001
Produced under the STATEMAP program, in cooperation with theU.S. Geological Survey, Department of Interior, Supported by
Cooperative Agreement 00-HQAG-0075
Sean Greeney
Iowa Department of Natural ResourcesJeffrey R. Vonk
Director
ACKNOWLEDGEMENTSRecognized for direct contributions to the map’s production:
Iowa DNR Geological Survey BureauDonald L. Koch and Matt Goolsby,
Index Showing Area of Geologic Map
Universal Transverse Mercator Projection, UTM Zone 15, North American Datum 1927
Kdw
Pc
Msp
Ma
Mg
Mmp
Om
Ogp
Dc
Dw
Df
Dl
LEGENDDescriptions of Rock Units
Rock Exposures in the Study Area
BUTLER
FLOYD
WRIGHT
HARDIN GRUNDY
FRANKLIN
HANCOCK
WORTH
HAMILTON
MITCHELL
CERRO GORDO
WINNEBAGO
Areas of bedrock exposure or bedrock surface within the soil horizon.
CRETACEOUS
Dakota and Windrow fms.; mid Cretaceous (upper Albian and/or Cenomanian); interval generally includedin Dakota Fm. across western map area, outliers in eastern map area generally assigned to Windrow Fm.Maximum thickness 150 ft (46 m) in Wright and Hancock counties. Primary lithologies: sandstone, partpebbly to conglomeratic , part cemented by iron oxides; mudstone, pale to medium gray, red. Secondarylithologies: chert residuum/gravel; siderite pellets .
P ENNSYLVANIAN
Cherokee Group undi fferentiated; Middle Pennsylvanian (Atokan-Desmoinesian). Maximum thickness:170 ft (52 m) in Hardin Co.; infilling of irregular erosional surface produces locally variable thickness.P rimary lithologies: shale, medium to dark gray, part sandy; sandstone, vf-c. Secondary lithologies: shale,black, carbonaceous; s iltstone; coal; underclay, pale gray. Minor: pebbly sandstone; shale, red to pale gray;s iderite concretions; limestone; pyrite.
M ISSISSIP PIAN
“St. Louis” and Pella fms.; Middle Mississippian (Meramecian). Maximum thickness 60 ft (18 m) inHamilton Co. P rimary lithologies: dolomite, part sandy; sandstone, part dolomitic; green-gray shale.Secondary lithologies: limestone, part sandy to sublithographic; breccia. Minor: oolitic limestone, chert.
Augusta Group, includes “Keokuk” and “Warsaw” fms.; Middle Mississippian (Osagean). Maximumthickness 85 ft (26 m); locally truncated beneath sub-“St. Louis” unconformity. Primary lithologies:dolomite, part argillaceous; dolomitic limestone; Secondary lithologies: green-gray shale; limestone, skeletalto sublithographic; glauconitic dolomite or limestone; breccia. Minor: chert, chalcedony and quartz; ooliticlimestone, phosphatic dolomite.
Gilmore City Fm., includes Marble Valley, Humboldt, and Iowa Falls mbrs.; Lower Mississippian(uppermost Kinderhookian, lower Osagean). Maximum thickness 170 ft (52 m) in Hamilton-Wrightcounties; thins southeastward, 50 ft (15 m) in southeast Hardin Co. Primary lithologies: limestone, skeletaland peloidal packstone-grainstone; limestone, oolitic to coated-grain; dolomite (Iowa Falls facies).Secondary lithologies: oncolitic, intraclastic , and sublithographic limestone; dolomitic limestone.
Maynes Creek and Prospect Hill fms., locally includes Chapin and Eagle City members within MaynesCreek interval; Lower Mississippian (Kinderhookian). Maximum total thickness 165 ft (50 m) in Hamilton-Wright counties, thins southeastward, 65 ft (20 m) in southeast Hardin Co.; maximum Maynes Creek Fm. 155ft (47 m); Chapin Fm 0-10 ft (3 m); maximum Prospect Hill Fm. 30 ft (9 m) in Franklin Co., elsewheregenerally <10 ft (3 m). Primary lithology: dolomite, part cherty to very cherty. Secondary lithologies:skeletal, oolitic , and sublithographic limestone; dolomitic limestone; silts tone (Prospect Hill). Minor: shale(Prospect Hill).
DEVONIAN
Famennian interval , includes upper shale (“Maple Mill”), Aplington Dolomite, Sheffield Shale; UpperDevonian (Famennian). Maximum thickness 150 ft (45 m) in Hardin Co., thins westward to 40 ft (12 m);Aplington Dolo.. locally to 50 ft (15 m). Primary lithologies: shale, green/olive-gray to gray, silty; dolomite,part argillaceous to s ilty, part cherty/siliceous. Minor: siltstone; oolitic ironstone (upper part), pyrite.
Lime Creek Fm., includes Juniper Hill, Cerro Gordo, and O wen members in eastern map area,undifferentiated to west; Upper Devonian (upper Frasnian). Maximum thickness 160 ft (49 m). Primarylithologies: shale, green-gray to gray, silty, calcareous; dolomite, part argillaceous (dolomite-dominated towest). Secondary lithologies: limestone, fossiliferous, part argillaceous. Minor: oolitic limestone, pyrite.
Cedar Valley Group; Shell Rock, Lithograph City, Coralville, Little Cedar fms.; Middle to Upper Devonian(upper Givetian-lower Frasnian). Maximum thickness 350 ft (107 m); truncated and overstepped westward inWinnebago Co.; maximum Little Cedar (Bassett, Chickasaw, Eagle Center, Hinkle mbrs.) 110 ft (34 m);maximum Coralville (Gizzard Creek, Iowa City mbrs.) 80 ft (24 m); maximum Lithograph City (OsageSprings, Idlewild mbrs .) 100 ft (30 m), maximum Shell Rock (Mason City, Rock Grove, Nora mbrs.) 75 ft(23 m). Primary lithologies: dolomite, fossil-moldic to vuggy; limestone, variably dolomitic, fossiliferous tosublithographic, part argillaceous. Secondary lithology: gray to green-gray shale, dolomitic. Minor:glauconitic dolomite; sandy dolomite or limestone; chert.
Wapsipinicon G roup; Pinicon Ridge, Spillville fms; Middle Devonian (upper Eifelian-lower Givetian);forms bedrock surface only in small areas of Floyd-Mitchell counties. Maximum thickness total interval: 130ft (40 m); maximum Spillville 90 ft (27 m); maximum Pinicon Ridge (Kenwood, Spring Grove-Davenportmbs.) 42 ft (13 m). Primary lithologies: dolomite, fossil-moldic to vuggy; dolomite, laminated or sandy;limestone, dense to sublithographic, partly to wholly brecciated. Secondary lithologies: shale, dolomitic tosandy. Minor: chert and chalcedony; sandstone.
ORDOVICIAN
Maquoketa Fm., Elgin Mbr.; Upper Ordovician (Richmondian), forms bedrock surface only in WinnebagoCo. Maximum thickness: 95 ft (29 m). Primary lithology: dolomite, part cherty to very cherty. Secondarylithology: limestone, fossiliferous, part cherty. Minor: shale.
G alena Group, includes Dubuque, Wise Lake, Dunleith, Decorah fms.; Upper Ordovician (Chatfieldian-Maysvillian); forms bedrock surface only in Winnebago Co. Maximum thickness 285 ft (87 m). Primarylithologies: limestone, part dolomitic; dolomite. Secondary lithologies: cherty limestone; cherty dolomite;green-gray shale, calcareous.
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Northwood
OsageForest City
Mason City
Garner
Charles City
Allison
Hampton
Clarion
Webster City
Eldora
Grundy Center
HARDIN
FLOYD
BUTLERWRIGHT
GRUNDY
FRANKLIN
HANCOCK
HAMILTON
WORTH MITCHELL
CERRO GORDO
WINNEBAGO
Df
Df
Df
DfDf
Df
DfMmp
Mmp
Mmp
MmpMmp
Mmp
Mmp
Mmp
Mmp
Om
Om
Om
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dl
Dl
Dl
Dl
Dl
Kdw
Kdw
Om
Om
Om
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dc
Dc Dc
Dc
Dw
Dw
Dc
Dl
Dl
Dl
Dc
Dc
Dc
Dc
Dc
Dc
DcDc
Dw
Dc
Dl
Mg
Mmp
Df
Pc
Pc
Kdw
Dl
Ogp
Kdw
Ma
Msp
Pc
Pc
Kdw
Mg
Dl
Dl
Msp
Pc
Pc
Msp
Msp
DlPc
Kdw
Ma
Pc
Dl
Msp
Msp
Ma
Kdw
Msp
Pc
Df
Mg
Ma
Pc
Ma
Pc
Kdw
Msp
Pc
Df
Pc
Pc
Ma
Kdw
Kdw
Kdw
Mmp
Pc
Ma
PcMsp
Kdw
Kdw
Dl
Kdw
Dc
Kdw
Dl
Pc
Pc
Dl
Kdw
Pc
Kdw
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Dl
Msp
Pc
Pc
Mg
Pc
Pc
Kdw
Pc
Df
Ma
Pc
Kdw
Ma
Pc
Df
Kdw
Mmp
Kdw
Df
Pc
Dl
Kdw
Pc
Df
Kdw
Pc
Pc
KdW
Pc
Df
Kdw
Ma
Kdw
Df
Kdw
Pc
Mg
Kdw
Kdw
Df
Ma
Kdw
Kdw
Ma
Kdw
Pc
Kdw
Kdw
Dc
Kdw
Msp
Kdw
Kdw
Pc
Kdw
Kdw
Msp
Mmp
Ma
Kdw
Mg
Dl
Kdw
Pc
PcMa
Kdw
Msp
Dl
Msp
Pc
Kdw
Df
Kdw
Kdw
Dl
Pc
Ma
Dc
Df
Mmp
Msp
Kdw
Ma
Kdw
Ma
Kdw
Msp
Pc
Kdw
Df
Df
Pc
Pc
Kdw
Pc
Kdw
Kdw
Pc
Df
Pc
Df
Dl
Mmp
Msp
Pc
Pc
Dl
Msp
Mmp
Mg
Pc
Mg
Kdw
Mg
Kdw
Mg
Ma
KdwKdw
Pc
Pc
Dl
Pc
Dl
Mg
Pc
Dl
Ma
Kdw
Ma
Pc
Msp
Kdw
Msp
Df
Pc
Pc
Msp
Ma
Ma
Kdw
DlDl
Kdw
Mg
Df
Kdw
Kdw
Df
Ma
Kdw
Kdw
Pc
DlDl
Dl
Kdw
Mmp
Dl
Kdw
Ma
Ma
Msp
Kdw
Mmp
Kdw
DlDl
Dl
Dl
Pc
Kdw
Dl
Kdw
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Msp
Dl
Ma
Dl
Ma
Kdw
Kdw
Kdw
Dl
Kdw
Kdw
Kdw
Kdw
Msp
Kdw
Kdw
Kdw
Kdw
Kdw
Dl
Mmp
Dl
Dl
Dl
Mmp
Kdw
Om
Ogp
Ogp
Om
Dw
Dw
Kdw
Dl
Dl
Kdw
Dc
Dc
DcDc
Dc
Dc
Dc
Dc
Dc
Dc
Kdw
Ma
Mg
Mg
Mg
Mg
Mg
Mg
Mg
Mg
Mg
Mg Mg
Mg
Mg
Mg
Mg
Mg
Mg
Mg
Mg
Mg
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Mg
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Msp
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Pc
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Mg
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Mmp
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Mmp
Mmp
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Pc
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Df
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DfDf
Df
Df
Df
Mg
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Dl
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Dl
Dl
Dl
Dl
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Dl
Dl
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Df
Dc
Dc
Dc
DcDc
Dc
Dc
Dc
Dc
Dc
DcDc
Dc
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Dc
Dc
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Dl
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Dl
Dl
Dl
Dl
Dl
Dl
Df
Df
Dl
Dl
Dl
Dl
Dl
Little Buffalo Creek
Dc
Ma
Ma
Clear Lake
Upper Pine
Lower Pine
Kdw
Mmp
Mmp
Kdw
Mg
Pc
Kdw
Mg
Mg
Mmp
Mmp
Mmp
Dl
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DfDf
Df
Df
Dc
Win
neba
go R
iver
Win
neba
go R
iver
Winn
ebag
o Rive
r
Winnebago River
Shell Rock River
Elk Creek
Cedar River
Cedar River
Little Cedar River
Wapsipinicon R
iver
Littl
e C
edar
Riv
er
Little Cedar River
Cedar River
Floyd Creek
Shell Rock River
Winnebago River
Wes
t Bra
nch
Iowa RiverE
ast Branch
Boone River
Iowa River
West Branch
Iowa R
iver
Boone
Rive
r
West Branch
Iowa River
Iowa River
Whit
e Fo
x Cre
ek
Cedar River
West Fork
Cedar River
West Fork
Floyd Creek
Shell Rock River
Shell Rock River
Beaver Creek
Beaver Creek
Beaver Creek
Blackhawk Creek
Lake
Lake
Iowa River
South Fork
Honey Creek
Iowa River
Sku
nk R
iver
Boone River
Boone
Rive
r
Pc
Pc
Pc
Dl
Mmp
Mmp
Kdw
Dc
Dc
Dc
Dc
Dc
Pc
Dc
Beeds Lake
93 30'o
93 30'o 93 00'o
o93 00'R26W R25W R24W R23W R22W R21W R20W R19W R18W R17W R16W R15W
R26W R25W R24W R23W R22W R21W R20W R19W R18W R17W
R16W R15W
T100N
T99N
T98N
T97N
T96N
T95N
T94N
T93N
T92N
T91N
T90N
T89N
T88N
T87N
T86N
T100N
T99N
T98N
T97N
T96N
T95N
T94N
T93N
T92N
T91N
T90N
T89N
T88N
T87N
T86N
43 00'o
o42 30'
43 30'o43 30'o
43 00'o
42 30'o
.-,35
.-,35
.-,35
.-,35
(/69
(/69
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(/218
(/218
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(/18
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(/18
(/18
(/20
(/20
(/20
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14
14
14
14
14
9
9
9
9
214
147
107
107
188
3333
57
17
17
175
175
175
175
175
359
214
299
Prepared by the Iowa Department of Natural Resources,Geological Survey Bureau, May 2001.
Open File Map 01-3